Patent Publication Number: US-11035870-B2

Title: Systems, methods and apparatus for identifying a specimen container cap

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention claims priority from U.S. Provisional Patent Application No. 62/366,350 filed Jul. 25, 2016, and titled “Systems, Methods And Apparatus For Identifying A Specimen Container Cap,” which is hereby incorporated by reference for all purposes. 
     The present invention is also related to and claims priority from PCT/US2017/014773 filed Jan. 24, 2017, and titled “Methods And Apparatus Adapted To Identify A Specimen Container From Multiple Lateral Views,” which is hereby incorporated by reference for all purposes. 
    
    
     FIELD 
     The present invention relates to pre-analytical methods and apparatus for use in biological specimen testing, and, more particularly, to methods and apparatus for determining a configuration of a specimen container cap. 
     BACKGROUND 
     Automated testing systems may conduct assays or clinical analysis using one or more reagents to identify an analyte or other constituent in a specimen such as urine, blood serum, blood plasma, interstitial liquid, cerebrospinal liquids, and the like. For convenience and safety reasons, these specimens are almost universally contained within sample containers (e.g., blood collection tubes), which may be capped with a container cap. The assay/test reactions generate various changes that may be read and/or manipulated to determine a concentration of analyte or other constituent contained in the specimen, that may, in some embodiments, be indicative of a patient&#39;s disease state. 
     Improvements in automated testing technology have been accompanied by corresponding advances in pre-analytical sample preparation and handling operations such as sorting, batch preparation, centrifugation of sample containers to separate sample constituents, cap removal to facilitate fluid access, sample container delivery, and the like by automated systems called Laboratory Automation Systems (LASs). LASs may automatically transport a specimen in a specimen container to one or more pre-analytical sample processing stations so that various operations can be performed thereon prior to performing the analysis. 
     These LASs may handle a number of different specimens contained in standard, barcode-labeled sample tubes. The barcode label may contain an accession number that may be correlated to demographic information that may be entered into a hospital&#39;s Laboratory Information System (LIS) along with test orders and other desired information. An operator may place the labeled specimen containers onto the LAS system, which may automatically sort and route the specimen containers for pre-analytical operations such as centrifugation, de-capping, and aliquot preparation, and all prior to the specimen actually being subjected to clinical analysis by one or more analyzers that may also be part of the LAS. 
     In testing systems, the specimen containers presented for analysis may be of varying sizes, such as of differing height and differing diameters and may also contain different materials, such as gel separator, clotting agent such as powdered glass clot activator or thrombin-based activator, anti-clotting agent such as ethylenediaminetetraacetic acid (EDTA), sodium or lithium-heparin, or acid citrate dextrose (ACD), antiglycolytic additives such as sodium fluoride and potassium oxalate. Cap color may be used to identify the different additives and may be indicative of the test type to be run on the specimen or simply tube type. For example, a red colored cap is sometimes used to refer to a serum collection tube, which may generally include a clotting agent such as a clot activator and may also include a gel separator. Orange caps may include a thrombin-based clot activator and may be used for stat testing where clotting is needed quickly. Anticoagulation cap colors such as purple may include EDTA and may identify basis hematology tube used for tests of blood type and counting cells. Light blue cap color may identify addition of sodium citrate for coagulation and platelet function tests. Green caps may identify tubes including lithium/sodium heparin for plasma tests. Yellow may include sodium polyanethol sulfonate and be used for bacterial growth and microbiology tests. 
     It is desirable to evaluate the sizes and types of the specimen containers including the caps without the use of visual inspection by a laboratory technician, but via an automated method because of the propensity for human error. Further, specimen containers may include barcode labels adhered directly to the specimen container. The one or more labels may partially occlude the specimen, so that there may not be clear opportunity to visually observe the serum or plasma portion of the specimen. Other systems, such as those described in US Pat. Pub. 2012/0140230 to Miller describe rotating the sample container to find a view window that is unobstructed by the label and then measuring the relative size of the specimen container and cap type using an optical imaging system. However, such systems may be less prone to ease of automation. 
     Because of the difficulties encountered in determining the size or type of specimen container and cap, there is an unmet need for a method and apparatus adapted to readily determine size and type as part of a pre-screening process. The method and apparatus carrying out the pre-screening should not appreciably adversely affect the speed that analytical test results are obtained, i.e., appreciably slow the overall testing process. Furthermore, the method and apparatus should be able to be used even on labeled sample containers and without rotation thereof. 
     SUMMARY 
     According to some aspects, a method of identifying a specimen container cap is provided. The method includes providing a specimen container including a container cap; capturing backlit images of the container cap taken at different exposures lengths and using a plurality of different nominal wavelengths; selecting optimally-exposed pixels from the images at different exposure lengths at each nominal wavelength to generate optimally-exposed image data for each nominal wavelength; classifying the optimally-exposed pixels as at least being one of a tube, a label or a cap; and identifying a shape of the container cap based upon the optimally-exposed pixels classified as being the cap and the image data for each nominal wavelength. 
     According to other aspects, a quality check module adapted to identify a specimen container cap is provided. The quality check module includes a plurality of cameras arranged at multiple viewpoints around an imaging location adapted to receive a specimen container including the cap, each of the plurality of cameras configured to capture multiple backlit images of at least a portion of the specimen container cap at different exposures lengths using different wavelengths of light from the multiple viewpoints, and a computer coupled to the plurality of cameras, the computer configured and operable to: select optimally-exposed pixels from the images at different exposure lengths at each nominal wavelength to generate optimally-exposed image data for each nominal wavelength; classify the optimally-exposed pixels as at least being one of a tube, a label or a cap; and identify a shape of the container cap based upon the optimally-exposed pixels classified as being the cap and the image data for each nominal wavelength. 
     In yet other aspects, a testing apparatus is provided. The testing apparatus includes a track, specimen carriers moveable on the track, the specimen carriers configured to carry specimen containers including container caps; and a quality check module arranged on the track and adapted to identify the container caps, the quality check module comprising: a plurality of cameras arranged at multiple viewpoints around an imaging location adapted to receive the specimen containers including the container caps, each of the plurality of cameras configured to capture multiple backlit images of the container cap at different exposure lengths and using different nominal wavelengths from the multiple viewpoints, and a computer coupled to the plurality of cameras, the computer configured and operable to: select optimally-exposed pixels from the images at different exposure lengths at each nominal wavelength to generate optimally-exposed image data for each nominal wavelength; classify the optimally-exposed pixels as at least being one of a tube, a label or a cap; and identify a shape of the container cap based upon the optimally-exposed pixels classified as being the cap and the image data for each nominal wavelength. 
     Still other aspects, features, and advantages of the present invention may be readily apparent from the following description by illustrating a number of example embodiments and implementations, including the best mode contemplated for carrying out the present invention. The present invention may also be capable of other and different embodiments, and its several details may be modified in various respects, all without departing from the scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. The invention is to cover all modifications, equivalents, and alternatives falling within the scope of the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings, described below, are for illustrative purposes only and are not necessarily drawn to scale. The drawings are not intended to limit the scope of the invention in any way. Like numerals are used throughout the drawings to denote like elements. 
         FIG. 1  illustrates a top view of a specimen testing apparatus including one or more quality check modules and one or more analyzers (clinical chemistry or assay instruments) according to one or more embodiments. 
         FIG. 2  illustrates a side view of a labeled specimen container including a separated specimen that may be quantified by a dimension quantification method according to one or more embodiments. 
         FIG. 3  illustrates a side view of a labeled specimen container including a separated specimen that may be quantified by a dimension quantification method according to one or more embodiments. 
         FIG. 4A  illustrates a schematic top view of a quality check module (with top housing portion removed to aid illustration) configured to capture and analyze multiple images according to one or more embodiments. 
         FIG. 4B  illustrates a schematic side view (with side housing portion removed to aid illustration) of the quality check module of  FIG. 4A  according to one or more embodiments. 
         FIG. 4C  illustrates a schematic top view of an alternate quality check module (with top housing portion removed to aid illustration) configured to capture and analyze multiple images according to one or more embodiments. 
         FIG. 4D  illustrates a schematic side view (with side housing portion removed to aid illustration) of the quality check module of  FIG. 4C  according to one or more embodiments. 
         FIG. 5  illustrates a flowchart of functional components of a quality check module adapted to quantify a specimen container according to one or more embodiments. 
         FIG. 6  illustrates flowchart of a broad imaging method adapted to quantify a specimen container according to one or more embodiments. 
         FIG. 7  illustrates flowchart of a method of quantifying a specimen container according to one or more embodiments. 
         FIG. 8  illustrates an example series of images of a container including a first example container cap taken using white light at different exposure lengths according to one or more embodiments. 
         FIG. 9  illustrates an example series of images of a container including a first example container cap taken using red light at different exposure lengths according to one or more embodiments. 
         FIG. 10  illustrates an example series of images of a container including a first example container cap taken using green light at different exposure lengths according to one or more embodiments. 
         FIG. 11  illustrates an example series of images of a container including a first example container cap taken using blue light at different exposure lengths according to one or more embodiments. 
         FIG. 12  illustrates an example series of images of a container including a second example container cap taken using white light at different exposure lengths according to one or more embodiments. 
         FIG. 13  illustrates an example series of images of a container including a second example container cap taken using red light at different exposure lengths according to one or more embodiments. 
         FIG. 14  illustrates an example series of images of a container including a second example container cap taken using green light at different exposure lengths according to one or more embodiments. 
         FIG. 15  illustrates an example series of images of a container including a second example container cap taken using blue light at different exposure lengths according to one or more embodiments. 
     
    
    
     DESCRIPTION 
     In a first broad aspect, embodiments of the present invention provide imaging methods and apparatus configured to, and capable of, being operated (operable) to determine physical attributes of a specimen container cap, such as the shape and geometry of the specimen container cap both externally and internally. In one or more embodiments, the method may determine the presence of a cap, may identify the cap type based on the shape of internal and external structures of the cap, and/or may identify the cap color. In one or more embodiments, a holder of the specimen container may also be identified so that its impact on the characterization can be eliminated or at least minimized. 
     A task during clinical lab automation procedures is the holistic characterization of a sample vessel, i.e., a specimen container; in particular the robust determination of the sample vessel type, i.e., the classification of the container cap type and the specimen container type itself is of high importance for automated diagnostics and robust decision making. For instance, it gives important information about the expected fluid structure during analysis. Usually specimen containers are laminated with various paper tags (e.g., manufacturer paper tags, tags with bar codes and others). This real world setup makes the classification challenging since specimen container type related features are occluded and therefore not visible and useful for accurate discrimination. RGB photos (e.g., captured under white light illumination) may be used to perform classification based on color and/or shape information. Various feature representations may be exploited for discrimination: color based or gradient based features may provide the basis for classification using well explored machine learning techniques (i.e., SVM, decision trees, neural networks, etc.) However, visible deviations between different specimen container types and container cap types are sometimes minor and thus, difficult to classify robustly. In addition real world conditions such as occlusion by paper tags make this task challenging using conventional illumination, e.g., ambient or front illumination. 
     Embodiments of the present invention provide an optical, automatic and contactless method to robustly characterize a specimen container and container cap by (1) classifying the visible container cap into a unique type extracted from a predefined and trained pool of container cap types and (2) classifying the specimen container type into a unique type of trained specimen containers. The pool of container caps may include thirty or more different types (e.g., capped specimen containers, TTSC (tube top sample cup) or plain specimen containers, etc.) which may vary in their appearance e.g., cap color (single or two color modes) and geometric shapes. Frequently, discrimination between various container cap types can be relatively straight forward, however, some of the types may only be discriminated by consideration of fine details, e.g., internal structures not visible under normal (front) illumination. The specimen container type itself may vary in material and structures. Typically normal specimen containers are used, but also capillary specimen containers and false bottom specimen containers may be presented to the system. In some embodiments, it is assumed that all specimen container types are known before a specimen container is to be identified. 
     Embodiments of the present invention uses the physical properties of the specimen container materials penetrated with high intensity illumination at different nominal wavelengths and/or wavelength ranges (e.g., white light) for different exposure lengths. Since the illumination source is placed behind the specimen container, each container cap pixel in the captured image encodes the amount of light going through the container cap material under a defined exposure time period (i.e., length) and wavelength. Internal structures of the specimen container will generate unique signatures (even through fibrous material like the paper tags) and thus, can be used for discrimination during machine learning based procedures. 
     Typically, when light (composed of multiple wavelengths) hits a material, components of the light may be absorbed, scattered or transmitted through the material. Given a fixed illumination source, the behavior of this effect is dominated by the material used. Materials enabling transmission of light through them are optically transparent, i.e. glass like materials used for TTSC (tube top sample cup) or uncapped specimen containers. Opaque material does not allow the transmission of any light wave frequencies, i.e. dark and solid caps or a certain number of overlaid paper tags. Most materials are composed of materials which are selective in their absorption of specific light frequencies, i.e. they absorb portions of the spectrum, (i.e., there is a main group of different specimen container caps (e.g., colored plastics based materials), a main group of variations, and also fibrous materials (e.g. paper tags)). 
     As will be illustrated in greater detail below, for specific exposure lengths, internal specimen container structures are visible (e.g., even through paper tags) and can therefore be used for discrimination between different specimen container types including container cap types. In particular, embodiments of the present invention are of great benefit in identifying the false bottom specimen containers where a paper tag can occlude major portions of the specimen container. Thus, reaching a specific amount of light energy for illumination may enable the visualization of discriminate internal structures which also provide specific patterns depending on wavelength specific responses on different material colors. A sample vessel is penetrated by back illumination at different exposure times and wavelengths. The patches captured with long exposure times clearly support the visualization of internal cap structures even through paper tags. White light illumination can be used but also a composition of responses from illumination using different nominal wavelengths can be used. Having multiple color responses can help to discriminate different colors of specimen container types. In some embodiments, varying exposure times are used to collect sufficient light energy with one or more camera sensors. 
     Specimen container characterization is performed using images acquired by a system adapted to capture a comprehensive 360 degree view of the specimen container including the container cap. The arrangement provides the system with individual but slightly overlapping images. The individual images show lateral views of the specimen container including the container cap from different viewpoints avoiding any blind spots. In some embodiments, the illumination is controlled by an LCD panel. The specimen container is placed between the camera and LCD panel. Additionally, in some embodiments of the inventive method, there are no required assumptions about the potential location or orientation of the specimen container. Having available 360 degree observation of the specimen container enables a consistent classification with respect to occlusions and also creates redundant specimen container observations (i.e., overlapping regions) to improve decision making from multiple views. For example, individual classification can be performed from three different viewpoints and the results aggregated over the three observations (e.g., late fusion). In some embodiments, the three views can be used together in a combined way during a single classification process (e.g., early fusion). 
     For specimen container type classification, embodiments of the present invention can use a stack of multispectral imagery captured with defined exposure lengths. A multispectral image may be composed of images collected at different wavelengths (and a relatively small bandwidth) responsive to the corresponding colors (absorption and reflections) i.e., representing red, green, blue portions. A potential input image may also be collected with white light configuration resulting in a conventional RGB images (e.g., 3 layers of information). 
     In some embodiments, from a pre-processing step, a binary image is assumed which masks out the specimen container portion of the sample vessel leaving the container cap portion. This mask may be generated by using a reference image and an observation showing the sample. Basic difference and thresholding computations may result in a binary mask. The binary mask drives the extraction of a rectangular 2D patch which depicts, e.g., the container cap only. A potential normalized image patch size may be of size 200×200 pixels. The image patch size may influence the processing time during testing. For example, a response time in the range of approximately 100 ms or less per image can be achieved. For specimen container type classification, the entire binary mask can be used instead of attempting to extract the relevant region. 
     For both container cap type and specimen container type classification a supervised machine learning method can be used. The method includes a training phase and a testing phase. Due to efficiency in classification and promising state-of-the-art results, a classification technique based on “deep learning” can be applied where the first layer takes a normalized image patch as input and the output layer provides a class label, i.e., a decision for one of the container cap types or specimen container types. In some embodiments, an image patch of size of W×H×3 is considered, where the three layers of information are generated directly from white light illumination or are composed from three different wavelength responses representing R, G, B colors. 
     In some embodiments a convolutional neural network (CNN) is used. For example, an extended version of “LeNet” can be used for image classification in the context of specimen container related recognitions. Another advantage of “deep learning” is the capability to handle of large amounts of data during the training process, thus avoiding sampling the data. 
     “Deep learning” has shown superior performance in generating discriminative feature representations directly from the considered training data. Thus, there is no need to design specific feature descriptors beforehand. In particular, this is helpful for the task of specimen container classification since fine structures, visualized by using back illuminated specimen containers, may provide discriminative power. 
     During the training phase, the classifier uses target ground truth labels. These labels may be generated at the level of sample vessels, which means that for each sample the system assumes a single unique label corresponding to describe the type of container cap. During the training process, a loss function is minimized using a gradient descent optimization of network parameters (i.e., weights), for example, minimizing the error made by the network under consideration of ground truth training labels. During the testing/classification phase, each image patch is parsed through the network and finally assigned confidence values for each particular container cap class or specimen container type class. The final object class may be extracted by arg-maximizing the set of confidence values. The aggregation over multiple views may be considered to generate the final decision for the specimen container observations. 
     Embodiments of the present invention provide image-based and contactless classification to discriminate a large number of different container cap types (e.g., number of types can be greater that 30 or more); image-based and contactless classification to discriminate complex specimen container types; automatic software based classification of container cap types using back illumination with varying wavelengths; automatic software based classification of specimen container types using back illumination with varying wavelength; automatic software based classification of container cap types using visualized internal structures due to high energy illumination; automatic software based classification of specimen container types using visualized internal structures due to high energy illumination; discrimination based on physical properties of the specimen container material; and learning a data specific feature representation for efficient classification of specimen containers and container cap types. 
     Knowing the width (W) of the specimen container can be used for further quantification (e.g., volume or depth) of the various portions of the specimen, such quantification of the serum or plasma portion, settled blood portion, or both. The cap type and/or cap color may be correlated with test requests from the LIS to verify that the proper specimen container has been used for the test that has been ordered, and/or to ensure that the test ordered will not be adversely impacted by any additives present in the specimen container. Height of the specimen container (HT) may be used by the robotic system to establish a home height for the pipette of an aspiration system to minimize specimen container-pipette collisions. Further, the HT may be used so that the any robot grippers may appropriately grasp the specimen container. 
     The specimen, as described herein, may be collected in a specimen container, such as a blood collection tube and may include a serum and plasma portion and a settled blood portion following fractionation (e.g., separation by centrifugation). The settled blood portion is made up blood cells such as white blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes), which are aggregated and separated from the serum or plasma portion, usually through undergoing centrifugation. The settled blood portion is generally found at a bottom part of the specimen container. The serum or plasma portion is the liquid component of blood, which is not part of the settled blood portion. It is generally found above the settled blood portion. 
     Plasma and serum differ in the content of coagulating components, primarily fibrinogen. Plasma is the un-clotted liquid, whereas serum refers to blood plasma, which has been allowed to clot, under the influence of a clotting agent such as endogenous enzymes or exogenous components. The serum or plasma portion will be made of serum or plasma depending upon whether exposed to a clotting agent. In some cases, the blood specimen may be exposed to an anti-clotting agent. In some specimen containers, a small gel separator may be used, which generally positions itself between the settled blood portion and the serum or plasma portion during centrifugation. It serves as a separation barrier between the two portions. 
     In accordance with one or more embodiments, the method may be carried out as a pre-analytical testing method, i.e., as pre-screening method before carrying out analysis on a clinical analyzer or assaying instrument. In one or more embodiments, the method may be carried out prior to, or simultaneous with, the specimen being quantified, characterized for the presence of an artifact (e.g., clot, bubble, or foam) and/or the presence of an interferent (e.g., hemolysis, Icterus, or Lipemia (HIL)). Thus, in one or more embodiments, the present invention provides useful characterization of the dimensions of the specimen container including the cap for further pre-analytical testing or for analytical testing after being pre-inspected for physical dimensions at a quality check module. 
     In one or more embodiments, the method uses high dynamic range (HDR) image processing to aid in determining the physical structure of the specimen container cap. Of course, in some embodiments, the identification of the location of various physical boundaries of the serum or plasma portion, and/or other blood components may also take place using HDR image processing. 
     In some embodiments, a quality check module configured to carry out the dimensional characterization method is provided. The quality check module may be provided in an area where a robotic or transport mechanism may transport specimens contained in such specimen containers to the quality check module. In some embodiments, the quality check module may be provided on a conveyor track, where the conveyor track carries the specimens to remote locations for analysis (e.g., analytical testing or assaying). Chemical analysis or assaying may take place on a suitable analyzer. The term “analyzer” as used herein means clinical chemistry analyzers, and/or assaying instruments, and/or the like. In some embodiments, the quality check module may be provided on the track so that the specimen container may be characterized for dimensions while resident on the track, such as on an input lane or elsewhere on the track. 
     In one or more embodiments, the processed HDR data may be used for dimensional characterization, but also for volume quantification, artifact detection, and/or HIL detection. All the captured images used by the dimension quantification method herein are pixelated images containing a plurality of pixels. Pixel as used herein means single pixels or a grouping of pixels, such as a super pixel. A super pixel having a size of 11 individual pixels by 11 individual pixels was found to work well for scanning and processing. Other suitable sizes of super pixels may be used. 
     In another aspect of one or more embodiments of the invention, the data on the width (W) of the specimen container obtained from the dimensional characterization can be used, along with boundary information obtained from segmentation to determine the depth or volume of the serum or plasma portion, and also possibly even a depth or volume of the settled blood portion. 
     The characterization method including HDR processing may include capturing multiple images at the quality check module at multiple exposures (e.g., exposure lengths), while illuminated by multiple different lights having different nominal wavelengths, and even from multiple viewpoints. In some embodiments, images may be captured with multiple cameras arranged within the quality check module. “Camera” as used herein means any device capable of capturing an image (e.g., digital image) for analysis. 
     The images captured by the multiple cameras are then processed by a computer to determine the shape and geometry of the container cap, and may also be used to quantify depths and/or volumes of the specimen. During a segmentation process, for each pixel in each of the images, pixels exhibiting optimal image intensity (i.e., optimal exposure) for each wavelength used may be selected and combined together with other optimal pixels from other pixel locations to generate consolidated image data sets. The result is a plurality of normalized, consolidated image data sets (e.g., red (R), green (G), blue (B)) where all of the pixels are optimally exposed (e.g., one image data set per each color (e.g., R, G, and B)). 
     The data from the normalized, consolidated color data sets may be subject to statistical analysis to determine statistical data on each pixel (e.g., mean and covariance matrix) thereof. “Covariance” is a measure of how much two or more of the pixel attributes such as intensity, correlate. This statistical data, in the form of one or more data matrices, can then be operated on by a multi-class classifier. From this, the shape of the specimen container cap may be classified. In particular, the external shape and structure of the container cap may be identified. Further, the internal shape and structure of the container cap, the type of container cap, and the color of the container cap may also be determined. 
     The multi-class classifier may be used to perform the segmentation task. The classifier may be a support vector machine (SVM) or a random decision tree, for example, that has been trained from multiple training sets. However, other types of classifiers may be used. 
     The dimensions of the specimen container including the container cap may be determined based upon the output from the segmentation process. The liquid region (i.e., the serum or plasma portion) may be defined by the classifier as well, and the boundary data together with the width (W) obtained by the dimensional characterization method may be used to determine a volume of the liquid region (e.g., serum or plasma portion). 
     Further details of inventive dimensional characterization methods, quality check modules, and specimen testing systems including the quality check module will be described with reference to  FIGS. 1 to 15  herein. 
       FIG. 1  illustrates a specimen testing apparatus  100  capable of and operable to automatically process multiple ones of the specimen containers  102  that may be contained in one or more racks  104  provided at a loading area  105  prior to analysis by one or more analyzers (e.g., first, second, and third analyzer  106 ,  108 ,  110 , respectively, arranged about the specimen testing apparatus  100 ). It should be apparent that more or less numbers of analyzers can be used. The analyzers may be one or more clinical chemistry analyzers and/or one or more assaying instruments, or the like, or combinations thereof. The specimen containers  102  may be any generally transparent or translucent container, such as blood collection tubes—see  FIG. 2 ). 
     Typically, specimens  212  ( FIG. 2 ) to be automatically processed may be provided to the specimen testing apparatus  100  in the specimen containers  102 , which may be capped with a cap  214  ( FIG. 2 —otherwise referred to as a stopper). The caps  214  may have different shapes, external structures, internal structures, and colors (e.g., red, royal blue, light blue, green, grey, tan, yellow, or other colors). The colors provide useful information about the testing to be performed, or the additives provided in the specimen container  102  in some instances. Each of the specimen containers  102  may include a tube  212 T that may be provided with identification information  215 , such as a barcode, alphabetic, numeric, or alphanumeric indicia, or combination thereof that may be machine readable at various locations about the specimen testing apparatus  100 . The identification information  215  may indicate a patient&#39;s identification and possibly tests be performed on the specimen  212 , for example. The identification information  215  may also be coordinated with a laboratory information system (LIS)  147  to provide additional information on the testing ordered or the like. Such identification information  215  may be generally provided on a label  218  adhered to, or otherwise provided on the side of, the specimen container  102 . The label  218  generally does not extend all the way around the girth of the specimen container  102 , or all along a length of the specimen container  102 . Accordingly, although the label  218  may occlude some portion of the specimen  212 , but some portion of the specimen  212  may still be viewable. In some embodiments multiple slightly overlapping labels  218  may be present. In some embodiments, the racks  104  may have additional identification information thereon that may be used for tracking. 
     After fractionation, the specimen  212  may include a serum or plasma portion  212 SP, a settled blood portion  212 SB contained within the tube  212 T. Air  212 A may be provided above the serum and plasma portion  212 SP and the line or demarcation between air  212 A and the serum or plasma portion  212 SP is defined herein as the liquid-air interface (LA). The line of demarcation between the serum or plasma portion  212 SP and the settled blood portion  212 SB is defined herein as the serum-blood interface (SB). The interface between the air  212 A and the cap  214  is referred to herein as the tube-cap interface (TC). The height of the tube (HT) is defined as the height from the physical bottom-most part of the tube  212 T to the bottom of the cap  214 . The height of the serum or plasma portion  212 SP is (HSP) is defined as the height from the top of the settled blood portion  212 SB to the top of the serum or plasma portion  212 SP, i.e., from SB to LA. The height of the settled blood portion  212 SB is (HSB) is defined as the height from the bottom of the settled blood portion  212 SB to the top of the settled blood portion  212 SB. In embodiments where a gel separator  313  is used, such as  FIG. 3 , an interface (SG) between the serum or plasma portion  212 SP and the gel separator  313  is present. Likewise, an interface (BG) between the settled blood portion  212 SB and the gel separator  313  is present. HTOT is HSB plus HSP in this case. W is the width of the tube  212 T. 
     In more detail, specimen testing apparatus  100  may include a base  120  (e.g., a frame or other structure) upon which a track  121  may be mounted or supported. Track  121  may be a railed track (e.g., monorail track or multiple rail track), a collection of conveyor belts, chains, moveable platforms, or other suitable conveyance mechanisms. Track  121  may have a circular, serpentine or other shape, and may be a closed (i.e., never ending) track in some embodiments. Track  121  may transport individual ones of the specimen containers  102  that may be carried on the track  121  in carriers  122 , or multiple ones of the specimen containers  102  in some embodiments. Specimen container  102  may be adapted to be received in a receptacle of the carrier  122  moveable on the track  121 . 
     In one or more embodiments, carriers  122  may be pucks that are configured to carry a single specimen container  102 . In some embodiments, the carrier  122  may include an onboard drive motor, such as a linear motor, that is configured to move the specimen container  102  about the track  121  while stopping and starting according to programmed instructions. Carriers  122  may each include a holder  122 H adapted to hold and secure the specimen container  102  in a defined upright position. Holder  122 H may include three or more thin leaf springs or fingers. 
     In some embodiments, carriers  122  may leave from the loading area  105  having one or more racks  104  thereat. Loading area  105  may serve a dual function of also allowing offloading of the specimen containers  102  from the carriers  122  after processing. A robot  124  may be provided at the loading area  105  and may be configured to grasp the specimen containers  102  from the one or more racks  104  and move and load the specimen containers  102  onto the carriers  122 , such as onto an input lane of the track  121 . Input lane may be part of the main portion of the track  121  or an offshoot therefrom. Robot  124  may also be configured to remove specimen containers  102  from the carriers  122  upon completion of testing. The robot  124  may include one or more (e.g., least two) robot arms or components capable of X and Z, Y and Z, X, Y, and Z, or r and theta motion, wherein the robot  124  may be equipped with robotic clamping fingers adapted to pick up and place the specimen containers  102 . However, any suitable type of robot  124  may be used. 
     Upon being loaded onto track  121  by robot  124 , the specimen containers  102  carried by carriers  122  may progress to a centrifuge  125  (e.g., an automated centrifuge configured to carry out fractionation of the specimen  212 ) and may be diverted to the centrifuge  125  by inflow lane  126  in some embodiments. After being centrifuged, the specimen containers  102  may exit on outflow lane  128  and continue on the track  121 . In some embodiments, the carriers  122  may move on to a quality check module  130  to be further described herein with reference to  FIGS. 4A-4D . Optionally, the centrifugation may occur previously and the specimens  212  contained in specimen containers  102  may be loaded directly into a quality check module  130  that is located at the loading area  105 , such as part of the input lane. 
     The quality check module  130  is configured and adapted to automatically determine/characterize physical attributes of the specimen container  102  (including the cap  214 ) containing the specimen  212  to be processed by the specimen testing apparatus  100 . Characterization may include characterizing tube size, cap type, and/or cap color. Once characterized, the specimen  212  may be further characterized to determine the depth and/or volume of the specimen  212 , screened for HIL, and/or a presence of one or more artifacts. If found to contain no HIL and/or no artifact(s), the specimens  212  may continue on the track  121  and then may be analyzed in the one or more analyzers (e.g., first, second and third analyzers  106 ,  108 , and/or  110 ) before returning each specimen container  102  to the loading area  105  for offloading. 
     In some embodiments, quantification of physical attributes of the specimen container  102  including the container cap  214  may take place at the quality check module  130  (i.e., determining HT, cap color, cap type, TC, tube type, and/or W). In some embodiments, quantification of the specimen  212  may also take place at the quality check module  130  and may involve determination of HSB, HSP, HTOT, and may determine a vertical location of SB, LA, SG, and/or BG. As will be apparent, the holder  122  may also be identified, but may be ignored when later processing the various images. 
     Additionally, a remote station  132  may be serviced by the automated specimen testing apparatus  100  even though the remote station  132  is not directly linked to the track  121  of the specimen testing apparatus  100 . For instance, an independent robot  133  (shown dotted) may carry specimen containers  102  to the remote station  132  and return them after testing/processing. Optionally, the specimen containers  102  may be manually removed and returned. Remote station  132  may be used to test for certain constituents, such as a hemolysis level, or may be used for further processing, such as to lower a lipemia level through additional processing, or remove an artifact found in the specimen  212 , such as a clot, bubble or foam, for example. Other testing or processing may be accomplished at remote station  132 . 
     The specimen testing apparatus  100  may include a number of sensors  116  at one or more locations around the track  121 . Sensors  116  may be used to detect a location of specimen containers  102  along the track  121  by means of reading the identification information  215  ( FIG. 2 ) placed on the specimen container  102 , or like information (not shown) that is provided on each carrier  122 , such as a barcode. Other means for tracking the location of the carriers  122  may be used. All of the sensors  116  interface with the computer  143  so that the location of each specimen container  102  and specimen  212  is known at all times. Computer  143  may interface and communicate with LIS  147  in a known manner. 
     Centrifuge  125  and each of the analyzers  106 ,  108 ,  110  may be generally equipped with robotic mechanisms and/or inflow lanes (e.g., inflow lanes  126 ,  134 ,  138 ,  144 ) configured to remove carriers  122  from the track  121 , and robotic mechanisms and/or outflow lanes (e.g., outflow lanes  128 ,  136 ,  141  and  146 ) configured to reenter carriers  122  to the track  121 . 
     Specimen testing apparatus  100  may be controlled by the computer  143 , which may include a microprocessor-based central processing unit CPU, having a suitable memory, software, and suitable conditioning electronics and drivers for operating the various system components. Computer  143  may be housed as part of, or separate from, the base  120  of the specimen testing apparatus  100 . The computer  143  may operate to control movement of the carriers  122  to and from the loading area  105 , motion about the track  121 , motion to and from the centrifuge  125 , operation of the centrifuge  125 , motion to and from the quality check module  130  as well as operation of the quality check module  130 , and motion to and from each analyzer  106 ,  108 ,  110 , and in some cases, possibly operation of each analyzer  106 ,  108 ,  110  carrying out the various types of testing (e.g., assay and/or clinical chemistry). 
     For all but the quality check module  130 , the computer  143  may control the specimen testing apparatus  100  according to software, firmware, and/or hardware commands or circuits such as those used on the Dimension® clinical chemistry analyzer sold by Siemens Healthcare Diagnostics Inc. of Tarrytown, N.Y., and such control is typical to those skilled in the art of computer-based electromechanical control programming and will not be further described herein. However, other suitable systems for controlling the specimen testing apparatus  100  may be used. The control of the quality check module  130  to characterize the specimen container and cap may also be provided by the computer  143 , but according to an inventive model-based method, as will be described in detail herein. Optionally, it could be provided by a separate computer coupled to the computer  143 . 
     Embodiments of the present invention may be implemented using a computer interface module (CIM)  145  that allows for a user to easily and quickly access a variety of control and status display screens. These control and status screens may describe some or all aspects of a plurality of interrelated automated devices used for preparation and analysis of specimens  212 . The CIM  145  may be employed to provide information about the operational status of a plurality of interrelated automated devices as well as information describing the location of any specimen  212  as well as a status of screening or tests to be performed on, or being performed on, the specimen  212 . The CIM  145  may be adapted to facilitate interactions between an operator and the specimen testing apparatus  100 . The CIM  145  may include a display screen adapted to display a menu including icons, scroll bars, boxes, and buttons through which the operator may interface with the specimen testing apparatus  100 . The menu may comprise a number of function buttons programmed to display functional aspects of the specimen testing apparatus  100 . 
     With reference to  FIGS. 4A-4B , a first embodiment of a quality check module  130  is shown and described. Quality check module  130  may be configured and adapted to automatically characterize a physical structure (e.g., size) of the specimen container  102  including the container cap  214 . The dimension and structural characterization method may be carried out by the quality check module  130  prior to being automatically processed by one or more of the analyzers  106 ,  108 ,  110 . In this manner, the size of the specimen container and the shape and structure of the container cap are known for any subsequent processing. The quality check module  130  may be used to quantify the specimen container  102 , i.e., quantify certain physical dimensional characteristics of the specimen container  102 , such as the location of TC, HT, and/or W and/or Wi of the specimen container  102 , and/or a color of, internal structure of, external structure of, and/or type of, the container cap  214 . The quality check module  130  may be used to quantify the holder  122 H such that the holder  122 H may be ignored when later processing the images. 
     In addition to the specimen container and container cap quantification method, other detection methods may take place on the specimen  212  contained in the specimen container  102  at the quality check module  130 . For example, the quality check module  130  may be used to quantify the specimen  212 , i.e., determine certain physical dimensional characteristics of the specimen  212  (e.g., a physical location of LA, SB, SG, and/or BG, and/or determination of HSP, HSB, and/or HTOT, and/or a volume of the serum or plasma portion (VSP) and/or a volume of the settled blood portion (VSB). 
     Again referring to  FIGS. 1, 4A and 4B , the quality check module  130  may include multiple cameras (e.g., two or more, three or more, four or more). Cameras may be conventional digital cameras (e.g., color or monochrome cameras), charged coupled devices (CCD), an array of photodetectors, two or more CMOS sensors, or the like. For example, three cameras  440 A,  440 B,  440 C are illustrated in  FIG. 4A  and may be configured to capture images at an imaging location from three different viewpoints. Other numbers of cameras may be used. Each camera  440 A,  440 B,  440 C may be a device capable of capturing a digital image (i.e., a pixelated image) at the imaging location. The image resolution of each image may be about 0.5 MP to 3 MP, for example. Other pixel resolutions may be used. Each camera  440 A,  440 B,  440 C may be configured and operable to capture lateral images of at least a segment or lateral portion of the specimen container  102  and the container cap  214  at the imaging location, and at least a portion of the specimen  212 , and possibly capture a part of the label  218 . The images may overlap slightly. Eventually, from the multiple images, a composite image of the container cap  214  and specimen  212  in the specimen container  102  can be developed. In some embodiments, the final composite image may be a 3D image of the specimen container  102 , the container cap  214 , and the contained specimen  212  at the imaging location based on images from the multiple cameras  440 A,  440 B,  440 C. 
     In the embodiment shown, the plurality of cameras  440 A,  440 B,  440 C may be arranged around the specimen  212  located at the imaging location and configured to capture lateral images from multiple viewpoints. The viewpoints may be radially spaced at approximately equally intervals from one another. As depicted, the intervals may be about 120 degrees from one another, when three cameras  440 A,  440 B,  440 C are used. In the example embodiment shown, the cameras  440 A,  440 B,  440 C may be arranged around the sides of the track  121 . Other arrangements of the plurality of cameras  440 A,  440 B,  440 C may be used. In this way, the images of the specimen container  102 , the container cap  214 , and the specimen  212  may be taken at the imaging location while the specimen container  102  is residing and held in the carrier  122  on the track  121 . 
     In one or more embodiments, the carrier  122  may be stopped at the pre-determined imaging location in the quality check module  130 , such as at a point where normal vectors from each of the cameras  440 A,  440 B,  440 C intersect. In some embodiments, a gate may be provided to stop the carrier  122 , so that good quality images may be captured. Gate may release the carrier  122  after the sequence of images are captured. In other embodiments, the carrier  122  may include a linear motor configured and programmed to start and stop the carrier  122  at desired locations, such as at the quality check module  130 . Other suitable means for stopping the carrier  122  may be used. 
     The cameras  440 A,  440 B,  440 C may be provided in close proximity to and trained and/or focused to capture an image window, i.e., an area including an expected location of the surface of the specimen container  102  and container cap  214 , wherein the specimen container  102  and/or container cap  214  may be approximately located in a center of the image window. As configured, the cameras  440 A,  440 B,  440 C can capture images that include portions of the serum or plasma portion  212 SP, portions of the settled blood portion  212 SB, and all of the container cap  214 . Within the images captured, one or more reference datum may be present. The reference datum may aid in further quantification of the specimen  212 , specimen container  102  and/or container cap  214 . Reference datum may be TC or a bottom-most surface of the specimen container  102 , or both. Optionally, the specimen containers  102  themselves may include a mark or other locating indicia provided thereon that can be viewed from any viewpoint. 
     In operation, each of the images captured by the quality check module  130  may be triggered and captured responsive to a triggering signal. The triggering signal may be generated by the computer  143  and provided in communication lines  443 A,  443 B,  443 C coupled to the computer  143 . Each of the captured images may be processed according to one or more embodiments of the method provided herein. In particular, HDR image processing may be used to capture and process the multiple images. 
     In more detail, multiple images are captured of the specimen container  102  at multiple different exposures (e.g., exposure lengths), and while illuminated by one or more different light sources having different nominal wavelengths. For example, each camera  440 A,  440 B,  440 C may take about 4-8 or more images at different exposure lengths using one or more light sources having different nominal wavelengths. Other numbers of multiple exposures may be taken. 
     Capture of the multiple images may be accomplished by several different methods. In some embodiments, the multiple images may be captured using different colored light sources  444 A- 444 C. The light sources  444 A- 444 C may backlight the specimen container  102  and container cap  214  (as shown in  FIGS. 4A-4B ) and may be embodied as light panels, for example. Light sources  444 A- 444 C may provide back lighting surrounding the imaging location  441 . Light sources  444 A- 444 C may be light panels. Light panels may include arrays of different colored lights therein or otherwise include means for pumping different colors of light therein. Light diffusers may be used in conjunction with the light sources  544 A- 544 C in some embodiments. The panels may provide uniform lighting of a desired spectral color or wavelength range. In this embodiment, the cameras  440 A- 440 C may be digital monochrome cameras. The light sources  444 A- 444 C may capture images at various spectra that have relatively narrow bandwidth of about +/−35 nm. In some embodiments, the light sources  444 A- 444 C may have nominal emission peaks at approximately 634 nm (red), 537 nm (green), and 455 nm (blue), respectively, for example. However, other nominal wavelengths may be used and more or less than three light sources may be used. Multi-wavelength, multi-exposure length images may then be captured by each of the cameras  440 A- 440 C from the different viewpoints. Each of the color images (represented by a nominal wavelength with some relatively narrow wavelength band) is captured, one after another, at various exposure lengths (e.g., 4-8 or more exposures, each exposure length may be approximately 8 ms to approximately 64 ms longer than the prior exposure length). Other exposure lengths can be used. The images may be taken in any order, such as red at multiple exposure lengths, green at multiple exposure lengths, and blue at multiple exposures lengths. For the detection method, transmittance images may be computed, wherein each transmittance image (for each of R, G, B illumination) is computed from optimally-exposed images and reference images, as will be apparent from the following. The optimally-exposed images may be normalized by their respective per-pixel intensity. 
     In optional embodiments, as best shown in  FIGS. 4C and 4D , the specimen container  102  may be front lit in the quality check module  130 A, such as by including light sources  444 D,  444 E, and  444 F arranged adjacent to the cameras  440 A,  440 B,  440 C, i.e., above, below, to the side, or combinations, but on the same side of the specimen container  102  as the respective cameras  440 A- 440 C. In this embodiment, the cameras  440 A- 440 C may be digital color cameras having RGB peaks of approximately 634 nm, 537 nm, and 455 nm, respectively, but wherein each of the RGB colors has a relatively wider wavelength range as compared to the discreet sources used in the above embodiment with the monochrome cameras. In this embodiment, the light sources  444 D,  444 E, and  444 F may each be white light sources. For example, the light sources  444 D- 444 F may emit a wavelength range of about 400 nm to about 700 nm and may be used to illuminate the specimen  212 . Multiple images at different exposure lengths may be taken by each camera  440 A- 440 C. Each white-light image captured may be separated into two or more color spectrum components at multiple n nominal wavelengths comprising at least two nominal wavelengths between about 400 nm and about 700 nm. For example, RGB spectral components may be separated out of the images by the computer  143  to generate the multi-spectral, multi-time exposure images. Images may be captured via signals from the computer  143  in lines  443 A- 443 C. 
     In some embodiments, the quality check module can include both front and back lighting of the specimen container  102  including the container cap  214  such that both front lit and backlit images can be captured. For example, in some embodiments a front lit image using white light can be captured, a sequence of backlit images each at different exposure lengths using white light can be captured, a front lit image using red light can be captured, a sequence of backlit images each at different exposure lengths using red light can be captured, a front lit image using green light can be captured, a sequence of backlit images each at different exposure lengths using green light can be captured, a front lit image using blue light can be captured, and a sequence of backlit images each at different exposure lengths using blue light can be captured. 
     To capture images at a first wavelength according to the first embodiment, three red light sources (nominal wavelength peak of about 634 nm with a spectral bandwidth of about +/−35 nm) may be used to simultaneously illuminate the specimen  212 . The red illumination by the light sources  444 A- 444 C may continue as multiple images (e.g., 4-8 or more images) at different exposure lengths are captured by each camera  440 A- 440 C, such as in synchronism. In some embodiments, the exposure times may be between about 0.1 ms and 256 ms. Other exposure times may be used. For example, the exposure times may be at 8 ms, another at 32 ms, another at 64 ms, and another at 128 ms. Other numbers of exposures and time intervals may be used to capture multiple exposure time images. The red light sources  444 A- 444 C may be turned on long enough to capture the multiple red backlit images and then may be turned off. 
     After capturing images using the red light sources  444 A- 444 C, they may be turned off and another color of light, for example, two or more green light sources  444 A- 444 C may be turned on (nominal wavelength peak of about 537 nm with a spectral bandwidth of about +/−35 nm), and multiple images (e.g., 4-8 or more images) at different exposure lengths may be captured at that spectra by each camera  440 A- 440 C arranged at the different viewpoints. This may be repeated with two or more blue light sources  444 A- 444 C (nominal wavelength peak of about 455 nm with a spectral bandwidth of about +/−35 nm) for each camera  440 A- 440 C. Thus, the result is a plurality of images captured at different exposure lengths, different spectra, and at different viewpoints. Other spectra, numbers of exposure times, or viewpoints may be optionally or additionally used. The different wavelength light sources  444 A- 444 C may be accomplished via use of exchangeable color filters, for example, or banks of different narrow-band colored RGB light sources that can be selectively turned on and off, for example. Other means for effectively back lighting may be used. Likewise, other colors than RGB may be used. 
     To capture images according to the second embodiment, three white light sources  444 D- 444 F may be used to simultaneously illuminate the container cap  214 . As illuminated by the light sources  444 D- 444 F, multiple images (e.g., 4-8 or more images) at different exposure times may be captured by each camera  440 A- 440 C, such as in synchronism. In some embodiments, the exposure times may be between about 0.1 ms and 256 ms, for example. Other exposure times may be used. For example, one exposure may be at 8 ms, another at 32 ms, another at 64 ms, and another at 128 ms. Other numbers of exposures and time intervals may be used to capture multiple exposure time images. The multiple exposure images may be further processed by computer  143  to extract individual RGB images (e.g., at lower pixel density) and at each of the exposure times and viewpoints. Thus, the result is a plurality of images per camera taken at different exposure lengths and illuminated with different light sources having different nominal wavelengths. 
     For each embodiment, all of these multi-spectrum images taken at multiple exposure lengths for each respective wavelength or wavelength range (e.g., white light) may be obtained in rapid succession, such that the entire collection of images for the container cap  214  (and specimen  212 ) from multiple viewpoints may be obtained in less than 2 s, for example. 
     To illustrate examples of the number of images captured for each specimen  212 , the following examples are provided. According to the first embodiment, using RGB light sources and 4 different time exposure images for each wavelength and providing monochrome cameras at three viewpoints will result in 4 exposures×3 colors×3 viewpoints=36 images. According to the second embodiment, using white light sources and 4 different exposure length images and providing color cameras at three viewpoints will result in 4 exposures×3 viewpoints=12 images. However, these 12 images are then separated into RGB images by the computer  143 , so that, in the end, 36 images are obtained, however the pixel density of these images is roughly ⅓ of the method of the first embodiment. In each case, the multi-exposure images may be stored in memory of the computer  143 , and may be subsequently processed thereby. According to a third embodiment, first using a white light source for front lighting of a first exposure and then using a white light source for back lighting at 3 different exposure lengths to capture images and providing cameras at three viewpoints, and then repeating for each of R, G, and B light sources will result in 4 exposures×4 wavelengths (or wavelength spectra (e.g., white light))×3 viewpoints=48 images. 
     In one or more embodiments, the quality check module  130  may include a housing  446  that may at least partially surround or cover the track  121  and provide a closed or semi-closed environment for image capture. The specimen container  102  may be located inside the housing  446  during each image capture. Housing  446  may include one or more doors  446 D to allow the carrier  122  to enter and/or exit the housing  446 . In some embodiments, the ceiling may include an opening  4460  to allow a specimen container  102  to be loaded into a carrier  122  stationed inside the housing  446  by a robot (e.g., robot  124 ) including moveable robot fingers from above, such as when the quality check module  130  is located at the loading area  105 . In cases where front lighting is used ( FIGS. 4C-4D ), the quality check module  130  may include backstop walls  447  to provide improved image contrast. Backstop walls  447  may be any suitable color, such as other than the expected range of color of the container cap  214 . In some embodiments, a black colored material may be used. 
     In one aspect, processing of the data of the multi-wavelength, multi-exposure length images may be directed at first determining a segmentation of the specimen  212  so that the tube  212 T and container cap  214  may be identified. The segmentation may also identify the liquid portion (e.g., the serum or plasma portion  212 SP). The processing may involve, for example, selection of optimally-exposed pixels from each of the multiple captured images taken at the different exposure times and at each wavelength for each camera so as to generate optimally-exposed image data set for each wavelength for each camera  440 A- 440 C. This is referred to as “image consolidation” herein. During image consolidation, for each spectral color, pixels in corresponding locations for each of the different exposure time images are compared, and only pixels exhibiting optimal image intensity may be selected from each of the different exposure time images. In one embodiment, optimal image intensity pixels may be pixels that fall within a predetermined range of intensity (e.g., between 180-254 on a scale of 0-255), for example. In another embodiment, optimal image intensity may be between 16-254 on a scale of 0-255, for example. Other non-optimal pixels are discarded as being under or over exposed. Other scales and optimal ranges may be used. If more than one pixel in the corresponding locations of two images is optimally exposed, then the higher intensity pixel of the two may be selected. Each of the optimally-exposed pixel intensities are then normalized per exposure time. The result is a plurality of normalized and consolidated spectral image data sets (e.g., red, green, blue) for each camera  440 A- 440 C where all of the pixels are optimally exposed (e.g., one image data set per spectra (e.g., red, green, blue)). 
     As part of the calibration process of the quality check module  130 , reference images without a specimen container  102  may be taken. The reference image(s) may be taken by each camera  440 A- 440 C prior to the specimen container  102  and carrier  122  entering into the quality check module and at all the exposure times and lighting conditions that will be later used during image capture. In this way, computational burden of the computer  143  may be minimized by optionally subtracting background (i.e., the region outside of the specimen container  102 ) from each image data set just leaving the foreground image. This is referred to as “background removal” herein. 
     For each spectral image data set including the normalized and optimally-exposed pixels, a segmentation process is undertaken to classify each of the pixels within the image data sets. The various segments of the specimen container  102 , container cap  214 , and specimen  212  may be characterized, i.e., each of the various classes and the boundaries thereof may be determined. This may be used to identify the tube  212 T, i.e., transparent or translucent regions, and the container cap  214 . This may also be used to identify the liquid portion (e.g., the serum or plasma portion  212 SP), gel separator  313  (if any), settled blood portion  212 SB, and lines of demarcation between the components (e.g., LA, SB, SG, BG). Background and carrier  212  may also be segmented. The segmentation may be based on classifying the pixels in the optimally-exposed image data as belonging to a class based upon a classifier model ( FIG. 5 ). The classifier model may be based upon a multi-class classifier  515  generated from multiple training sets. The multi-class classifier  515  may comprise a support vector machine (SVM) or a random decision tree, for example. Other types of multi-class classifiers may be used. 
     To carry out the classification, first statistical data may be computed for each of the optimally-exposed pixels at the different wavelengths (e.g., red, green, blue) and for each camera  440 A- 440 C. The statistical data may include mean values and variances up to 2 nd  order. Once generated, the statistical data is presented to and operated on by the multi-class classifier  515 , which may classify the pixels in the images as belonging to one of a plurality of unique class labels, such as 1—serum or plasma portion, 2—settled blood portion, 3—cap, 4—label, 5—specimen container, 6—air, 7—gel separator (if used), 8—tube (e.g., the transparent region). Carrier  122  may also be classified. From this segmentation, the pixels making up the tube  212 T and the container cap  214  may be identified. 
     The results of the operation of the multi-class classifier  515  are to identify all pixels that are of the class 3—cap and class 8—tube. A simple flow chart of the specimen container characterization method is shown in  FIG. 5 . First the specimen container  102  including specimen  212  being carried by carrier  122  is provided at the quality check module  130  in  502 . Multiple exposure images are captured at  504 ; the multiple exposure images being multi-spectral images taken at multiple different exposure times and at multiple different spectra (and/or wavelengths ranges) as described above. The multiple images may then be stored in memory of the computer  143 . From these images, the background may optionally be subtracted in a background removal phase of  508  to lower computational burden. Background reduction is accomplished by subtracting reference images taken in  510 , which may be taken as part of a calibration or as part of the method before carrier  122  and the specimen container  102  are provided at the imaging location  441 . 
     After image capture, and possible background removal, the segmentation process may be accomplished on the multiple exposure, multiple wavelength data sets for each camera  440 A- 440 C, as shown in  511 . The segmentation process in  511  may include an image consolidation phase that may be undertaken in  512 . During image consolidation in  512 , the various images of each color (e.g., nominal wavelength) are reviewed pixel by pixel to determine those pixels that are optimally exposed. For each corresponding pixel location, the best of any optimally-exposed pixel is selected and included in an optimally-exposed image data set. Each pixel intensity value is normalized by the exposure time. Thus, following image consolidation in  512 , there is produced one normalized and optimally-exposed image data set for each nominal wavelength or wavelength range (e.g., color). 
     Following image consolidation in  512 , or possibly concurrent therewith, a statistics generation process is undertaken in  514  where statistics are generated for each pixel, such as mean and/or covariance matrix. This statistical data and intensity information from the normalized and optimally-exposed data sets are then operated on by a multi-class classifier  515  to provide identification of pixel classes in  516  for all pixels in the image data sets. From this classification process of  516 , each pixel in a consolidated image for each of the cameras  440 A- 440 C is given a classification as being one of the plurality of class types, as listed above. During classification, the image is scanned and for each pixel location a class label is derived by using the multi-class classifier. In some embodiments, small super-pixel patches around the pixel location are used to make statistical description more robust with respect to the noise level of the cameras  440 A- 440 C (e.g., 11×11 pixels). 
     From this, the pixels that are tube  212 T and container cap  214  are identified. All the pixels classified as container cap  214  are collected together. From this, the shape of the cap  214  (e.g., the shapes of both internal and external structures of the container cap  214 ) may be identified by, for example, blob or other suitable shape analysis technique in  531  by comparing the identified shape to a database of reference cap internal and external shapes stored in memory of the computer  143 , such as in look-up tale  531 L or other database. Internal and external shapes of the container cap  214  identifies the cap type in  531 . Internal and external shapes of the container cap  214  may indicate the type of material present in the specimen container, such as urine, sputum, feces and whether the container is under vacuum. Internal and external shapes of the container cap  214  may also indicate whether the specimen container has been evacuated. In some embodiments, in addition to, or as an alternative to shape analysis, the dimensions (e.g., height, width, diameter, thickness, etc.) of the container cap  214  can be determined from the pixels identified as representing the cap. 
     The same collection of pixels that have been identified as representative of the container cap  214  may be quantified for an average R, G, and B levels or a clustering approach in case of multi-colored caps, and from this RGB data the color of the cap  214  may be identified in  533  based upon a comparison of individual ranges of RGB values for known cap colors stored in a lookup table  533 L. For an identified cap region the real color values may be extracted. Color calibration may occur at any desirable time prior to testing. Each real color value or multiple color values would be matched to database entries (e.g., via a look-up table or other association), where all cap colors are represented. 
     The tube  212 T may be quantified by collecting together the various pixels identified in  516  as being of the class tube. The positions in pixel space between respective outermost lines of pixels of the tube  212 T that are aligned substantially vertically are then subtracted to calculate and extract the width (W) in  518 . The width (W) may be calculated as an average of the distances between the corresponding pixels at corresponding heights. The pixels measured in  518  may be those that are below the tube-cap interface TC, while ignoring pixels at the curved portion of the bottom of the specimen container  102 . 
     The height (HT) is then extracted in  520 . The height (HT) is measured between the bottom-most pixels classified as tube  212 T and the tube-cap interface TC. This height (HT) value may be taken, together with the width (W), to identify and characterize the size of the specimen container  102  from a list of possible sizes in  529  that may be stored in a look-up table  529 L, for example (e.g., 10.25×47, 10.25×64, 10.25×84, 13×75, 16×100, 13×100, all in mm×mm). Other standard sizes may be listed. 
     From these values, an estimated inner width (Wi) may be determined in  535 . This inner width (Wi) may be used for calculations of volume of the serum or plasma portion  212 SP and/or volume of the settled blood portion  212 SB. The inner width (Wi) may be estimated based upon actual measured or estimated wall thickness (Tw) for each specimen container  102  of each size. These inner width (Wi) values may be stored on memory, such as in a look-up table  535 L and useable for the volume measurements once the tube size is identified. 
       FIG. 6  illustrates a flowchart of a broader characterization method  600  wherein the characterization of the specimen container  102  (including the container cap  214 ) containing the specimen  212  is just one of the many items that may be characterized or classified by the broader method  600  using the quality check module  130 . According to one or more embodiments of the method  600 , images are captured, such as by multiple cameras (camera  540 A is shown). However, other cameras  540 B,  540 C may be used to capture images from other viewpoints. The processing that will be described for the images captured on camera  540 A is identical for the other cameras  540 B,  540 C at the other viewpoints and their inputs in line  605  may be used to develop a 3D model of the specimen  212 . The images captured by camera  540 A and the other cameras  540 B,  540 C may be multi-spectral and multi-exposure images, as discussed above. In particular, multiple exposures (e.g., 4-8 or more exposures) may be taken for each wavelength of light used in  604 A. The respective images at each exposure for each camera  540 A- 540 C may be obtained simultaneously using monochrome cameras and backlight light sources  544 A- 544 C as described in  FIGS. 4A-4B . Optionally, front illuminated multi-exposure images using a white light sources  544 D- 544 F may be obtained in  604 B using a color camera. 
     The images may then be processed in  508  to remove background using reference images  510  as described above in optional background removal method. The images are then further processed to determine segmentation in  511  in the manner described above. In some embodiments, the images from front lit cameras  540 A- 540 C (see  FIGS. 4C-4D ) from  604 B may be best used for segmentation in  511 . Likewise, the images captured in  604 A may be best used for characterization of HILN in  621 . However, clearly, images captured in  604 B could be used for segmentation in  511 . 
     Identifying and quantification of the liquid in  623  may also be carried out following segmentation in  511 . Quantifying the liquid in  623  may involve the determination of certain physical dimensional characteristics of the specimen  212  such as a physical location of LA, SB, SG, and/or BG, and/or determination of HSP, HSB, and/or HTOT, and/or a volume of the serum or plasma portion (VSP) and/or a volume of the settled blood portion (VSB). The inner width (Wi) may be obtained from the specimen container characterization  627  as was described above. The identification may be accomplished by selecting the pixels at these demarcation areas and averaging their location values in pixel space to obtain a value for LA, SB or SPG. From this information, the volume of the serum or plasma portion  212 SP may be determined. Correlation from pixel space to mechanical measurements may be accomplished by using any suitable calibration to calibrate pixel to mm. 
     To provide an even closer measurement of the actual volume of serum or plasma portion  212 SP available, an artifact detection method may be employed in  622  to identify a presence of clot, bubbles, or foam. The respective estimated volume of the one or more artifacts present may be subtracted from the estimated volume of the serum or plasma portion  212 SP determined above to obtain a better volume estimate. The images may then be processed to determine the presence of or absence of an artifact in the serum or plasma portion  212 SP in  622  using an artifact classifiers. Those pixels including artifacts identified in artifact detection  622  may then be ignored be the HILN classification in  621 . Detection of an artifact may also initiate a remediation in some embodiments. 
     The results of the segmentation in  511  can also be used to identify the label which may include the identifying information  215 , such as a barcode. The barcode may be read in  625 . Conventional barcode reading software may be used once the label  218  is identified by the segmentation in  511 . If that image does not contain enough of the barcode to be read, the barcode can be read from the other images obtained from outer cameras. 
     Further characterization of the specimen container  102  may also be accomplished according to the broader method  600 . The characterization of the tube type in  529 , cap type in  531  and cap color in  533  may be fed to the 3D reasoning in  635  to verify that the same characterization was achieved based on processing the images from each camera. If slightly different values are obtained, then the values may be averaged. All of these outputs from the HILN Classification in  621 , liquid quantification in  623 , artifact detection in  622 , and specimen container detection in  627  may be fed into the 3D reasoning in  735  and may be used to generate a 3D model. 
       FIG. 7  illustrates a flowchart of a method of determining characteristics of a specimen container  102  including the container cap  214  according to one or more embodiments. The method  700  includes providing a specimen container (e.g., specimen container  102 , such as a capped, blood collection tube) in  702 . Next, the method  700  includes capturing images of the specimen container and container cap at different exposures lengths and at different wavelengths in  704 . For example, there may be 4 to 8 or more different exposures taken in some embodiments. Some images may be captured using white light for front lighting and some may be captured using a plurality of single-wavelength peak, narrow-band light sources, such as red, blue and green as backlit light sources  544 A- 544 C. The white light images may be resolved into R, G, and B images as captured by the computer  143 , as discussed above. In each instance, the images may be taken by multiple cameras  540 A- 540 C from multiple viewpoints. 
     The method  700  may optionally include, as shown in  706 , background reduction to subtract the background in order to lower computational burden. Background reduction may be accomplished by subtracting the reference images from the captured specimen images, which may be taken as part of a calibration process. Reference images may be taken at the same exposure times, spectrum, and lighting conditions as for the specimen images of the specimen container  102 , but may be captured without a specimen container  102  or the carrier  122 . 
     The method  700  includes, in  710 , selecting optimally-exposed pixels from the images at different exposure times at each wavelength to generate optimally-exposed image data at each wavelength. For each corresponding pixel in each image at a particular spectra, the best exposed pixel (not under or over exposed) is selected. The optimal exposure range may be as discussed above. This selecting optimally-exposed pixels takes place in an image consolidation phase (e.g., image consolidation  512 ). Thus, for each of the RGB spectra, a data set of optimally-exposed pixels is generated. 
     Next, the method  700  includes classifying the optimally-exposed pixels as being tube  212 T, label  218 , or container cap  214  in  714 . Classifying may be accomplished by computing statistical data of the optimally-exposed pixels at the different wavelengths to generate statistical data, and then operating on the statistical data of the optimally-exposed pixels to identify at least one of tube  212 T, label  218 , or container cap  214 . Other classes (e.g., serum or plasma portion  212 SP, settled blood portion  212 SB, gel separator  313 , and/or air  212 A) may also be identified by the segmentation. 
     In one or more embodiments, the multi-class classifier may be a support vector machine (SVM) that is either linear or kernel-based. Optionally, multi-class classifier may be a boosting classifier such as an adaptive boosting classifier (e.g., AdaBoost, LogitBoost, or the like), any artificial neural network, a tree-based classifier (e.g., decision tree, random decision forests), a logistic regression as a classifier, or the like. SVM may be particularly effective for classification between liquids (e.g., serum or plasma portion  212 SP) and non-liquids such as cap, tube, or label. A SVM is a supervised learning model with associated learning algorithms that analyzes data and recognizes patterns. SVMs are used for classification and regression analysis. 
     Multiple sets of training examples are used to train the multi-class classifier, and then the pixels are operated on by the multi-class classifier and are marked as belonging to one of the multiple classes, as discussed above. A training algorithm builds the multi-class classifier and assigns any new examples into one of the classes. Thus, the multi-class classifier may be a non-probabilistic linear classifier in some embodiments. The SVM model represents examples as points in space that are mapped so that the examples of the separate classes are divided by a clear gap that is as wide as possible. Pixels from the optimally-exposed image data set may be mapped into that same feature space and predicted to belong to a particular class based on where they fall. In some embodiments, SVMs can efficiently perform a non-linear classification using what is called a kernel trick (e.g., kernel-based SVM classifier), implicitly mapping their inputs into high-dimensional feature spaces. SVM and boosting may also be used. Other types of multi-class classifiers may be used. 
     The multi-class classifier may be trained by graphically outlining various regions (e.g., tube  212 T, container cap  214 , air  212 A, and label  218 ) in a multitude of examples of specimen containers  102  having various tube sizes, and/or cap types and colors, and labels  218 . As many as 500 or more images may be used for training the multi-class classifier. Each training image may be outlined manually to identify and teach the multi-class classifier which areas belong to each class. Other training methods may be used. 
     Finally, the method  700  includes identifying a width, height, or width and height of the specimen container based upon the optimally-exposed image data for each wavelength in  714 . 
     In some embodiments, once the specimen container  102  has been given a characterization of size, such as from height and width, volume of the specimen  212 , the inside width (Wi) of the specimen container  102  may be obtained. The inner width (Wi) may be determined in  716 , such as by using a lookup table based upon the size of the specimen container  102 . The inner width (Wi) may be used to accurately calculate volume of the serum or plasma portion  212 SP and/or the volume of the settled blood portion  212  SB. 
     Accordingly, based on the foregoing it should be apparent that the model-based specimen container characterization method  700  carried out by the quality check module  130  may result in a rapid characterization of the physical attributes of the specimen container  102  such as tube size, cap type, and cap color. Based upon this information, accurate volumes may be determined, cross checks between the ordered tests and specimen container used, and verification that the additives present are compatible with the test ordered. 
     While the quality check module  130  has been shown in  FIG. 1  as being located such that the pre-screening is performed immediately after centrifugation on the centrifuge  125 , it may be advantageous to include the quality check module  130  directly on an analyzer (e.g., analyzer  106 ,  108 , and/or  110 ) in some embodiments, or elsewhere. For example, stand-alone analyzers that are not connected to an automated specimen container handling system could use the quality check module  130  to validate specimens  212  prior to analysis. Furthermore, in some embodiments, the centrifugation may be performed prior to loading the racks  104  into the loading area  105 , so that in some embodiments, the quality check module  130  may be located at the loading area  105  and the quality check can be carried out as soon as the robot  124  loads a specimen container  102  into a carrier  122 . Other locations for the quality check module  130  are possible. 
     Turning now to  FIGS. 8 to 11 and 12 to 15 , two example sets of images are shown. As shown in the first group  800  of images of the first example set of  FIGS. 8 to 11 , white light (e.g., the visible light spectrum ranging from approximately 390 nm to approximately 700 nm) can be used to capture a first front lit image  802  and to capture a sequence of backlit images  804 ,  806 ,  808  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). As can be seen, the longer the exposure length of the backlit images, the higher the light transmittance through the various different densities of the container cap and thus, the more visible relatively dense internal structures of the container caps become while relatively less dense portions become washed out. Likewise, as shown in the second group  900  of images of the first example set of  FIGS. 8 to 11 , red light (e.g., having a nominal wavelength of approximately 634 nm) can be used to capture a first front lit image  902  and to capture a sequence of backlit images  904 ,  906 ,  908  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). Likewise, as shown in the third group  1000  of images of the first example set of  FIGS. 8 to 11 , green light (e.g., having a nominal wavelength of approximately 537 nm) can be used to capture a first front lit image  1002  and to capture a sequence of backlit images  1004 ,  1006 ,  1008  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). Likewise, as shown in the fourth group  1100  of images of the first example set of  FIGS. 8 to 11 , blue light (e.g., having a nominal wavelength of approximately 455 nm) can be used to capture a first front lit image  1102  and to capture a sequence of backlit images  1104 ,  1106 ,  1108  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). 
     A different example container cap is depicted in the second set of images in  FIGS. 12 to 15  to further illustrate the benefit of illuminating the container caps with different wavelength light for different exposure lengths. As shown in the first group  1200  of images of the second example set of  FIGS. 12 to 15 , white light (e.g., the visible light spectrum ranging from approximately 390 nm to approximately 700 nm) can be used to capture a first front lit image  1202  and to capture a sequence of backlit images  1204 ,  1206 ,  1208  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). As can be seen, the longer the exposure length of the backlit images, the higher the light transmittance through the various different densities of the container cap and thus, the more visible relatively dense internal structures of the container caps become while relatively less dense portions become washed out. Likewise, as shown in the second group  1300  of images of the second example set of  FIGS. 12 to 15 , red light (e.g., having a nominal wavelength of approximately 634 nm) can be used to capture a first front lit image  1302  and to capture a sequence of backlit images  1304 ,  1306 ,  1308  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). Likewise, as shown in the third group  1400  of images of the second example set of  FIGS. 12 to 15 , green light (e.g., having a nominal wavelength of approximately 537 nm) can be used to capture a first front lit image  1402  and to capture a sequence of backlit images  1404 ,  1406 ,  1408  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). Likewise, as shown in the fourth group  1500  of images of the second example set of  FIGS. 12 to 15 , blue light (e.g., having a nominal wavelength of approximately 455 nm) can be used to capture a first front lit image  1502  and to capture a sequence of backlit images  1504 ,  1506 ,  1508  each taken at different exposure lengths (e.g., 8 ms, 16 ms, and 32 ms). 
     The two example sets of images (Tube  1  shown in  FIGS. 8 to 11 , and Tube  2  shown in  FIGS. 12 to 15 ), illustrate how much more clearly the methods and apparatus of the present invention depicts the differences in container caps. Tube  1  has a red colored container cap and almost every portion of the structure is absorbed for red light. Backlit image  904  taken after 16 ms of exposure to red light (e.g., at a nominal wavelength of 450 nm) most clearly illustrates the internal structure of the container cap of Tube  1 . Tube  2  has a green colored container cap and as can be seen, the green spectral portions become transparent. Backlit image  1408  taken after 64 ms of exposure to green light (e.g., at a nominal wavelength of 560 nm) most clearly illustrates the internal structure of the container cap of Tube  2 . The differences between the images of the two container caps clearly indicate that the materials used to construct the container caps are different. In particular, the green cap of Tube  2  is denser than the red cap of Tube  1 . 
     In some embodiments, the lighting used to back illuminate the container caps can be of sufficient intensity that the internal structures and shapes of the container caps are revealed in at least some of the captured images for at least one of the nominal wavelengths. In other words, in some embodiments an intensity for the backlighting can be chosen such that at least some light will penetrate the known container cap types to be identified. In some embodiments, a backlight source having an intensity in the range of approximately 2 W/m 2  to approximately 4 W/m 2  can be used, and in some embodiments approximately 3 W/m 2 . Backlighting of other intensity levels can be used. Since different color container caps absorb different nominal wavelengths differently, by using multiple nominal wavelengths (e.g., at least three different nominal wavelengths), lower overall intensity light can be used to capture images that reveal the internal structures of the container caps then would be needed if white light was used or a single nominal wavelength was used. Note that in embodiments where it is desirable to use lower power (e.g., lower intensity) lighting, longer exposure lengths can be used. Further, in embodiments where faster imaging is desired, higher power (e.g., higher intensity) lighting can be used to reduce the exposure lengths. 
     While the invention is susceptible to various modifications and alternative forms, specific apparatus embodiments and methods thereof have been shown by way of example in the drawings and are described in detail herein. It should be understood, however, that it is not intended to limit the invention to the particular apparatus or methods disclosed but, to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention.