Abstract:
A system, method and device for grading of meat such as bovine, porcine, sheep, horse or poultry meat among others. The device of this invention is a portable tool, which is approached toward a meat specimen to be analyzed and captures an image. The device then objectively relates the image to meat quality parameters by means of an image analyzing method. The device and method solve, in a practical, fast and satisfactory way, the problem of determining meat quality parameters such as texture, color, and contained intramuscular fat percentage.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/909,222, filed Mar. 30, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 6,751,364 (incorporated herein by reference) divulges an image analysis system and method for the grading of meat, predicting quality of meat and/or predicting meat yield of an animal. One embodiment of the invention is particularly designed to capture an image of the 12 th  rib cross section of the ribeye and perform an image analysis of the ribeye for grading purposes. The image capturing camera portion of the system has a wedged shaped camera housing for easy of insertion into the ribbed incision. Once the image is captured either digitally or captured and converted to a digital image, an image analysis is performed on the digital image to determine parameters such as the percent lean, total area of the ribeye, total fat area, total lean area, percent marbling, and thickness of fat adjacent to the ribeye, and other parameters. These parameters are used to predict value determining traits of the carcass. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention relates to a portable device for determining meat quality with possible minimum error, thus replacing a human grader with computer-assisted grader (artificial vision). Analyzed meat may be bovine, porcine, sheep, horse or poultry meat. 
     The present application implies developing a new method of measuring parameters such as meat fat, texture and color by means of a method that allows relating said meat quality parameters to values obtained from images. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is the device of the present invention. 
         FIG. 2  is the main flow diagram of color, texture, and intramuscular analysis of a meat specimen. 
         FIG. 3  is a flow diagram of sub-routine capture of digital image. 
         FIG. 4  is a flow diagram of sub-routine that determines texture values. 
         FIG. 5  is a flow diagram of sub-routine that determines intramuscular fat percentage. 
         FIG. 6  is a flow diagram of sub-routine that determines color (CIE-Lab coordinates). 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The present description comprises some specific technical terms, which will be detailed below in order to avoid misinterpretations regarding other uses thereof or meanings that can be connected to the same terms. 
     The term “artificial vision” refers to the image captured by an electronic device and the computational interpretation of said image. This term is also known as “computer vision”, and corresponds to a sub-field of artificial intelligence. The purpose of the artificial vision is programming a computer, which due to said programming should “understand” a scene or image features. 
     The term “channel” refers to a primary meat unit from an animal that was insensitized, bled, skinned, and gutted, where its head was cut at the atlanto-occipital joint, its external genital organs were also cut as well as its limbs, which were cut at carpometacarpal and tarso-metatarsal joints. 
     The term “meat texture” refers to the sensorial manifestation of foodstuff structure and the way it reacts before the application of forces, such as shear stress. It is considered a food-grade parameter, since it directly produces an effect on the palatability, and said effect is noted only when meat has been subjected to a boiling process. It is directly determined by properties of conjunctive myofibril structures of the cytoskeleton, which differ greatly and depend on specie, race, gender, and age, thus producing an effect on technological and biological variables. 
     The term “intramuscular fat percentage”, also referred as marbling, relates to the visible fat amount in a meat cut. Intramuscular fat amount produces an effect on meat flavor, tenderness and juicy character, mainly depending on gender, slaughtering age and principally on genetic type. Meat fat quality basically depends on feedstuff composition consumed by the animal during the fattening stage. 
     Terms such as “color space”, “color modules” or “color systems” correspond to a coordinate system and an area or sub-space within said system, where each color is represented by a single point. A color space allows specifying and visualizing any color. Psycho-physical parameters of color perception are three: brightness, tone, and saturation. In the present invention use of color spaces are as follows: 
     Color space RGB, which is based on the combination of three different chromatic luminance signals: red (R), green (G), and blue (B). Graphically it is represented by a cube. Gray tones are represented by a straight line linking origin (0, 0, 0) with point (255, 255, 255) over which the three color components have the same magnitude. This corresponds to coordinated space used by electronic devices such as digital cameras and monitors. 
     Color space “XYZ” utilizes a brightness component (component “Y”) and two coloring or chromaticity components, which corresponds to components “X” and “Z”. Components “X”, “Y”, and “Z” have a value ranging from 0 to 100. Values of each component are obtained by means of integration or adding, which involves a lighting source, object reflectance, and sensitivity curves of a standard human observer. Quantitative colorimetry utilizes three data pieces to calculate colors: the energy of the luminous source (400 to 700 nm), the reflectance of the object and the curves of sensitivity of the eye. 
     Color space “Lab” represents colors by means of the scale of Hunter Lab, which is one of the easiest scales to interpret in the food industry. It uses parameters L, a, and b, where “L” measures the luminosity in a scale from 0 to 100, where 100 represents the color white and 0 represents the color black, “a” measures red tonalities (+127) until green (−128), and “b” measures yellow tonalities (+127) until blue (−128). 
     Lab coordinates can be obtained by means of mathematical formulae from values of coordinates XYZ and values of X 0 , Y 0 , Z 0 , that represent the “white pattern” of the system, for example:
 
 L*= 116−( Y/Y   0 ) 1/3 −16
 
 a*= 500·[( X/X   0 ) 1/3 −( Y/Y   0 ) 1/3 ]
 
 b*= 200·[( Y/Y   0 ) 1/3 −( Z/Z   0 ) 1/3 ]
 
     The term “image segmentation” refers to the technique by which an object of interest in an image can be separated from the “background” of the image. It does not necessarily identify the object category. For example, if it relates to a character like the letter “A”, the segmentation only identifies the image area where it is possible to find this character. 
     From the image a pair of referential points or pixels is selected (the corresponding minimum and maximum value in gray scale). 
     Each point or pixel of the image is selected according to its proximity with respect to these referential points. 
     Accordingly, the image points are separated in two categories, which show a similarity in their values of gray level. Particularly, these categories correspond to the group of pixels that correspond to meat and the pixels that do not correspond to meat, i.e., they correspond to the image background. 
     The term “thresholding” refers to a technique used in image segmentation. Thresholding is the method by which a level of threshold “T” is chosen in order to classify each pixel of the image f (x,y). If the pixel meets or exceeds the threshold property, for example f (x,y)&gt;T, then the pixel is assigned to the object class; otherwise, the pixel is assigned to the background class. 
     For example, the Otsu&#39;s method may be used as a thresholding method. This is an iterative method that calculates an optimal threshold for a standardized histogram comprising two pixel distributions. The method assumes that the histogram is formed by two Gaussian curves, and that threshold T shall minimize the weighted sum of each one of the variances of the present objects. 
     Device Definition 
     The objective of the present invention relates to producing a portable device for determining meat quality with the minimum possible error, thus replacing a human grader with a computer-assisted grader (artificial vision). This invention also relates to a method of measuring parameters such as meat fat, texture and color by relating meat quality parameters to values obtained from images captured by a portable device. 
     The present invention consists of a system capable of objectively measuring meat quality parameters, and use of an image analyzing method captures images of meat quality parameters with no need to manipulate the meat. 
     The system of the present invention comprises a portable device which captures images of a meat specimen to be analyzed; and uses an image analyzing method to determine meat quality parameters that are measured using understandable units of the meat industry. Finally, the obtained results are displayed on a screen. 
     The present portable device ( FIG. 1 ) consists of a casing, preferably a tubular-shaped casing (a), that comprises a handle (b) on which a trigger (c) is arranged, and a screen or display (h). Inside the casing (a) an image-capturing device (e) is arranged. A microcontroller (f) is arranged outside of the casing, but may alternatively be arranged inside the casing, and is connected to the trigger and the display, respectively, in order to proceed with the actuation of the device and the data display. Furthermore, inside the casing a lighting system and a light backscatter system (g) are provided to obtain a uniform image without optical aberration. The device of  FIG. 1  further comprises a camera support (d). 
     Other components of the portable device (not shown in  FIG. 1 ) are electric power- and data feeder cables, which transfer the captured image to a required portable personal computer. Furthermore, a polarizing lens can be added to reduce brightness, and a filter to correct the color temperature in the opening zone (i) of the image-capturing device (e). Surface (j) corresponds to the device portion that comes in contact with the sample to be analyzed. 
     Some relevant aspects to be considered for the measurement of meat quality parameters are meat origin (sheep, bovine or other meat), meat type, etc. in order to determine quality parameters properly. 
     Image analysis is performed on a computer by an image analyzing method, which has been particularly designed for this purpose and is actuated by capturing an image. The analysis of said image is performed and parameter results are displayed both on the screen of the computer and on the display of the device of the present invention, where said parameters were measured with user understandable units. 
     The indicated analysis performed by a certain method allows measurement of three quality parameters of meat such as meat texture, meat color, and intramuscular fat percentage. The values of each are displayed in a comprehensible form to the user (i.e. in measurement units used in foodstuffs science). 
     The method for obtaining said meat parameters begins with positioning and contacting the portable device to a meat specimen, where said portable device comprises a lighting system to homogenize the light inside said apparatus, and an image capturing device which captures a specimen image. 
     The method for obtaining meat quality parameters from an image is semi-automatic, as the method is controlled by a computational program that is run by the operator once the image capturing device is triggered. Said programming activates the image capturing device and subsequently processes the captured image and displays the processed image on a screen. Once the computational programming is run, it checks the device status, which includes verification of the status of the image capturing device, among others. Verification of the status of the image capturing device checks feeding status, memory status, communication with the computer, etc. If there is any erroneous parameter, the programming shows an error message; if not, said programming goes through an automatic configuration process of the device intended for the image capturing process. The configuration states image format, image storage location (which can be either a temporal location or a location for storing the corresponding image for future verifications), exposure time, focus adjust, diaphragm opening, white balance, etc. Once ready, the image is captured and stored in a previously selected address. Subsequently the programming checks the image capturing device once more. 
     In the present invention the artificial vision is used for determining meat quality parameters. 
     In order to perform the image analysis a technique using Artificial Neural Networks (ANN) is utilized. Artificial Neural Networks are capable of “learning”, such as through backpropogation techniques, and due to this feature said artificial neural networks can transform data captured from an image into data of any other nature (conventional methods), such as data obtained by a Warner-Bratzler colorimeter, etc. Artificial Neural Networks (ANN) are prepared such that they can connect an inlet value to an outlet value. In the present invention said inlet value corresponds to a value obtained from data selected from the captured specimen image, whereas said outlet value refers to the result of the respective parameter, which is obtained by a physical or chemical method regarding the same specimen. 
     Outlet values for each parameter are intramuscular fat percentage, meat texture and color, which are determined by means of the following physical techniques: 
     Determination of Intramuscular Fat 
     The method of determining intramuscular fat percentage is based on the technique relating to the use of a graduated jig according to National Cattlemen&#39;s Beef Association; United States Department of Agriculture. 
     In said method a tag-blog is provided on the wet specimen which shows a squared grid drawn thereon. Then the operator proceeds to count those zones corresponding either to meat or fat inside said squared grid. Intramuscular fat percentage is calculated by means of a simple rule of three. 
     Texture Determination 
     The method for determining meat texture is based on Warner-Bratzler&#39;s technique. 
     From each meat cut cores cylinders, also referred as “cores”, having a diameter of about 1.27 cm and a height of about 2.5 cm are obtained, wherein each cylinder shall be oriented parallel to muscle fibers. Then temperature is adjusted to 1-3° C., and subsequently said specimens are subjected to room temperature. After 5 minutes each cylinder (core) is sheared by means of a Warner-Bratzler probe executing a cut perpendicular to muscle fibers once at a rate of 200 mm/min and an approach rate of 80 mm/min and a pre-load of 0.01 Kg.F. 
     A texturometer having a maximum load cell of 500N (DO-FB05TS Model 2003, Zwick, Ulm, Germany) was utilized. Texture is expressed as Maximum Force at Kg.F with a mean value of 6 measurements. 
     Color Determination 
     Method for determining meat color was carried out by measuring specimen reflectance. Said reflectance analysis was performed on a Miniscan XE Plus model N o  45/0-1 Hunterlab, which utilizes CIELAB system expressing results in terms of variables L, a and b. Six measurements of each specimen are performed and made on the specimen surface. Equipment is programmed at an observation angle of 10° with illuminant D65, which is similar to daylight, using an absolute scale for coordinates L, a and b, wherein color is defined in a three-dimensional and spherical space. A mean value of the 6 measurements represent the value of each variable. 
     The image analyzing method comprises the following stages: color analysis, texture analysis, and analysis of meat fat percentage. The obtained results are finally displayed on screen in a user understandable manner. 
     Meat Texture Analysis 
     Texture analysis is performed by means of an analysis sub-routine, which begins with the recovery of an image stored in a defined address in the computer hard disc. To this, an image clustering function is applied, which cuts or segments the image to be analyzed, selecting from said image only areas representing a meat image, and the remaining elements are discarded (image background). Then the image is subdivided in several sub-images of less size, e.g., of 128×128 pixels. Each of these images is analyzed to determine whether they correspond to meat or background (background is black; if image contains black pixels it will be discarded). Finally considered images are subjected to a Wavelet analysis by which a vector comprised of 8 RMS values for each sub-image or sub-area is obtained. Once this data is obtained and by means of a co-relation made by the prepared Artificial Neural Network, obtained variables are converted to a single shearing-force value. Obtained values for each image are averaged at a final stage, and said mean value, which is referred as F TOTAL , is the value corresponding to the mean texture measurement. 
     Analysis of Intramuscular Fat Percentage 
     Another relevant parameter is the mean quality measurement, which corresponds to the intramuscular fat percentage contained in a meat cut. 
     The process for obtaining the value of intramuscular fat percentage begins with the recovery of an image stored in computer hard disc. Then the program accentuates interest zones of said image by means of simple linear and non-linear operations, such as multiplying the image by itself, filtering undesired brightness, adjusting intensity, etc. In this manner a superior contrast between image and background is reached. Image segmentation is then performed in order to separate background from the interest zone. 
     Image coordinates RGB are converted into coordinates CMY (better resolution) and then the colored image is converted into a gray-scale image. Subsequently a thresholding method is applied, which uses an adaptive method to look for the proper threshold according to a histogram of the image being analyzed in order to achieve a discrimination among different gray tones that correspond to white and black. 
     The white and black pixels are counted, thus obtaining fat and meat areas in the cut. Subsequently areas corresponding to fat and meat are calculated and they are converted into intramuscular fat percentage contained in the cut. This result is finally displayed on a screen. 
     Color Analysis of Meat Specimen 
     The color obtaining process begins with the recovery of an image stored in a computer hard disc. Subsequently the number of pixels of this image is reduced and then the image portion to be analyzed is segmented by means of a function referred to as clustering, considering meat zones only. From this image coordinates RGB are obtained, which are specimen representative. Then the artificial neural network converts RGB color space into XYZ color space of colored zones (meat zones) and differentiates colored zones through data co-relation to convert previous coordinates into XYZ coordinates, and then into CIE Lab coordinates. Finally CIE Lab coordinates are displayed and recorded, thus obtaining mean color of the analyzed meat cut and the program is ready to start again.