Patent Publication Number: US-2018040124-A1

Title: Disease diagnostic apparatus, image processing method in the same apparatus, and medium storing program associated with the same method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional Application of U.S. Ser. No. 14/860,603 filed Sep. 21, 2015, which claims priority from Japanese Patent Application No. 2014-227527 filed Nov. 7, 2014, the contents of both of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a disease diagnostic apparatus, an image processing method in the same apparatus, and a medium storing a program associated with the same method. 
     BACKGROUND ART 
     Generally, visual inspection is necessarily performed to diagnose a cutaneous legion, thereby obtaining an amount of information. However, not only discrimination between a mole and a spot but also discrimination between a benign tumor and a malignant tumor are substantially difficult with a naked eye inspection and even a magnifying glass inspection. For the reasons, dermoscopic inspection in which a dermoscope-equipped camera is used to capture an image of a disease has been conventionally performed. 
     The dermascope is a noninvasive diagnostic device in which a disease irradiated with light from, for example, a halogen lamp, and unobstructed by reflective light due to echo gel or a polarization filter is magnified (typically ×10) and subjected to observation. A dermoscopic diagnosis can be defined as the inspection of skin diseases with the dermoscope. For more detail, see internet URL (http://www.twmu.ac.jp/DNH/department/dermatology/dermoscopy.html) (accessed on Sep. 1, 2014). In accordance with the dermoscopic diagnosis, scattered reflection occurring due to a cuticle is eliminated, thereby rendering the distribution of pigmentation from an epidermis to a superficial intradermal layer increasingly visible. 
     For example, Patent Literature 1 (Japanese patent publication No. 2005-192944 (A)) discloses technologies of a remote diagnosis apparatus of diagnosing a pigmented skin disease employing a value such as color, a texture, an asymmetricity, and a circularity based on an image of a skin captured by the dermoscope. In accordance with Patent Literature 1, a portable phone provided with a dermoscope-equipped camera is used, and an image of a skin having a disease of a benign nevus pigmentosus and etc. and having a risk of a melanoma is captured by the dermoscope. The portable phone is connected to an internet due to its network connecting function, and the image of the skin captured is transmitted via the internet to the remote diagnosis apparatus to request a diagnosis. Upon receiving the image of the skin based on the request, the remote diagnosis apparatus uses a melanoma diagnosis program to determine whether based on the image of the skin the disease is a melanoma or not, or in a case where the disease is the melanoma, which stage of the melanoma is. The determination as a result is transmitted to a physician having requested the diagnosis. 
     While diagnosis that is performed based on the afore-mentioned dermoscopic image has become widely used, clear shape change or feature is often difficult to obtain. In addition, an observation of the image and a determination of a disease actually depend on a skill of a physician or clinician. For the reasons, a tool allowing for easy and accurate diagnosis based on image processing technologies of, for example, highlighting a disease portion in the dermoscopic image, has been desired. 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] Japanese patent publication No. 2005-192944 (A) 
     SUMMARY OF INVENTION 
     In accordance with a first aspect of the invention, there is provided a method of processing an image in a diagnostic apparatus of diagnosing a disease using a captured image of an affected area, comprising: a separating step of separating the captured image into a brightness component and a color information component; and an extracting step of extracting a region to be diagnosed based on the brightness component or the color information component of the configured image to highlight likeness of the region. 
     In accordance with a second aspect of the invention, there is provided a diagnostic apparatus of diagnosing a disease using a captured image of an affected area, comprising: an image-memorizing unit configured to memorize the captured image; and a processing unit configured to process the captured image memorized in the image-memorizing unit, the processing unit comprising: a separating unit configured to separate the captured image into a brightness component and a color information component, and an extracting unit configured to extract a region to be diagnosed based on the brightness component or the color information component of the configured image to highlight likeness of the region. 
     In accordance with a third aspect of the invention, there is provided a non-transitory computer readable medium storing a program of processing an image in a diagnostic apparatus of diagnosing a disease using a captured image of an affected area, the program causing a computer to execute: a separating step of separating the captured image memorized into a brightness component and a color information component; and an extracting step of extracting a region to be diagnosed based on the brightness component or the color information component of the configured image to highlight likeness of the region. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing a configuration of Embodiment of a diagnostic apparatus in accordance with the present invention. 
         FIG. 2  is a flow chart illustrating a basic processing operation of Embodiment of the diagnostic apparatus. 
         FIG. 3  is a flow chart illustrating the details of operation of extracting likeness of vessel. 
         FIG. 4  is an exemplary display screen configuration of Embodiment of the diagnostic apparatus. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Referring to the accompanying drawings, Embodiment of the invention will be hereinafter described in detail. Furthermore, the same reference numeral is assigned to the same element or part throughout the overall specification. 
     Configuration of Embodiment 
       FIG. 1  is a block diagram showing a configuration of a diagnostic apparatus  100  in accordance with Embodiment of the present invention. Referring to  FIG. 1 , an image-capturing device  110  equipped with a dermoscope, which can be hereinafter designated as an “image-capturing device  110 ” or “dermoscope-equipped, image-capturing device  110 ” throughout the specification, is connected to the diagnostic apparatus  100 . The dermoscope-equipped, image-capturing device  110  is configured to capture an image of an affected area in accordance with an instruction from the diagnostic apparatus  100  (a processing unit  101 ), memorize the captured image (i.e., a dermoscopic image) in an image-memorizing unit  102 , and display the captured image on a predetermined area of a display device  120 . Furthermore, the captured image is highlighted by the processing unit  101 , and then memorized in the image-memorizing unit  102  and displayed on the predetermined area of the display device  120 . An input device  130  is configured to perform an instruction for starting to capture an image such as a dermoscopic image, and selection of a region in the dermoscopic image, which will be described below. 
     The display device  120  may be a LCD (Liquid Crystal Display) monitor, and the input device  130  may be a mouse. 
     The processing unit  101  is configured to process the captured image such as the dermoscopic image, of the affected area memorized in the image-memorizing unit  102 . Referring to  FIG. 1 , the processing unit  101  has separating means  101   a , extracting means  101   b , and generating means  101   c.    
     The separating means  101   a  function as means for separating the captured image into a brightness component and a color information component. The extracting means  101   b  function as means for extracting a region to be diagnosed such as a vessel-corresponding region based on the brightness component or the color information component of the captured image so as to highlight the likeness of the region. 
     The generating means  101   c  function as means for combining the extracted result of the region as mentioned previously with a background image to generate a reconstructed image. In this regard, the background image is selected by physician&#39;s operation with the input device  130 , and is at least one selected from the group consisting of the captured image, a grayscale image of the captured image, a contrast-highlighted image of the captured image, and a brightness component-highlighted image that is obtained by separating a brightness component of the captured image into a base component (also called a large-scale component) and a detail component and performing highlighting process on the base component and the detail component in a different manner. 
     Each of the separating means  101   a , the extracting means  101   b , and the generating means  101   c  as described above can execute the afore-mentioned original function thereof by the processing unit  101 &#39;s sequentially reading a program in accordance with Embodiment of the present invention, owned by the processing unit  101 . 
     Operation of Embodiment 
     The operation of the diagnostic apparatus  100  in accordance with Embodiment of the present invention as shown in  FIG. 1  is described in detail with the following operational examples with reference to  FIG. 2  and below. 
       FIG. 2  depicts the flow of basic processing operation of the diagnostic apparatus  100  in accordance with Embodiment of the present invention. Referring to  FIG. 2 , the processing unit  101  firstly acquires an image of an affected area (i.e., a skin legion) that is captured by the dermoscope-equipped, image-capturing device  110  (Step S 11 ). Then, the captured image as acquired is memorized in the predetermined area of the image-memorizing unit  102 , and is displayed on the display device  120  (Step S 12 ). 
     An exemplary image of a display screen displayed on the display device  120  is shown in  FIG. 4 . In the screen of  FIG. 4 , a captured image-displaying section  121  in which the captured image is displayed is arranged at a left side and a highlighted image-displaying section  122  in which the highlighted image such as the highlighted image of vessel is displayed is arranged at a right side. For example, upon the physician&#39;s clicking a button of “start to capture image”  123  which is located at a bottom right of the screen, the dermoscope-equipped, image-capturing device  110  can start to capture the image of the affected area, and the processing unit  101  can acquire the captured image and display the captured image in the captured image-displaying section  121  of the display device  120 . 
     Furthermore, there are provided checkboxes  124 ,  125 , and  126 , which are located at a bottom left of the screen and provided for the designation of display type of the vessel region. When the physician wishes to display an image where highlighting is performed on the captured image with red color, an image where highlighting is performed on monochrome captured image with red color, or a vascular image, he or she does a selection operation (i.e., an operation of clicking) with the input device  130 , thereby rendering the associated checkbox  124 ,  125 , or  126  check-marked. 
     Returning to the flow chart of  FIG. 2 , after the processing unit  101  displays the captured image as acquired in the captured image-displaying section  121  of the display device  120 , it extracts a vascular region as a likelihood V from the captured image (Step S 13 ). In this regard, if the vascular region has two values, it has a value of 1 or 2. If the vascular region has multiple values, it has a value of from 0 to 1. In the above, “0” means a non-vascular region and “1” means the vascular region. The process of extracting the vascular region as the likelihood V is described below. 
     Next, the processing unit  101  acquires information regarding the display type designated by the physician from the state of the checkboxes  124 ,  125 , and  126  displayed on the display screen of the display device  120 . Once the physician&#39;s selecting any of the checkboxes  124 ,  125 , and  126 , the processing unit  101  highlights the vessel-corresponding region based on the selected display type and displays the highlighted image as thus obtained in the highlighted image-displaying section  122 . 
     Specifically, when the checkbox  124  has been selected (Step S 14 : “combining with captured image”), the generating means  101   c  of the processing unit  101  generate the vessel-highlighted image E in which the vascular region is indicated by red color on the captured image IMG (Step S 15 ). In this regard, the vessel-highlighted image E can be generated in accordance with the following mathematical formula: E=IMG.*(1−V)+Red*V. In the above mathematical formula, “IMG.” represents the captured image; “Red” represents red color; “*” represents multiplication; and “.*” represents multiplication per an element. Subsequently, the processing unit  101  displays the generated, vessel-highlighted image E in the highlighted image-displaying section  122  together with and next to the captured image displayed in the captured image-displaying section  121  of the display device  120  (Step S 16 ). 
     On the other hand, when the checkbox  125  has been selected (Step S 14 : “combining with grayscale image”), the generating means  101   c  of the processing unit  101  convert the captured image to the grayscale image, and then generate the vessel-highlighted image E in which the vascular region is indicated by red color (Step S 17 ). In this regard, the vessel-highlighted image E can be generated in accordance with the following mathematical formula: E=Gray(IMG).*(1−V)+Red*V. In the above mathematical formula, “Gray ( )” represents conversion to the grayscale image. Subsequently, the processing unit  101  displays the generated, vessel-highlighted image E in the highlighted image-displaying section  122  together with and next to the captured image displayed in the captured image-displaying section  121  of the display device  120  (Step S 16 ). 
     Furthermore, when the checkbox  126  has been selected (Step S 14 : “displaying vascular image”), the generating means  101   c  of the processing unit  101  generate the vessel-highlighted image in which the vascular portion is indicated by red color and the non-vascular portion is indicated by black color (Step S 18 ). In this regard, the vessel-highlighted image E can be generated in accordance with the following mathematical formula: E=Red*V. While the vascular region is indicated by red color, the color is not limited to red color and can be thus arbitrarily selected. Subsequently, the processing unit  101  displays the generated, vessel-highlighted image E in the highlighted image-displaying section  122  together with and next to the captured image displayed in the captured image-displaying section  121  of the display device  120  (Step S 16 ). 
     The extracting process of the vascular region as the likelihood V as defined in Step S 13  is described with reference to the flow chart of  FIG. 3 . Referring to  FIG. 3 , the separating means  101   a  of the processing unit  101  firstly convert the captured image from RGB color space to Lab color space (more exactly, CIE 1976 L*a*b* color space). The details of the Lab color space are described in, for example, internet URL (http://Ja.wikipedia.org/wiki/Lab % E8%89% B2% E7% A9% BA % E9%96%93) (accessed on Sep. 1, 2014). 
     Subsequently, the extracting means  101   b  of the processing unit  101  use image L (i.e., a brightness image) of the Lab color space that is acquired by the separating means  101   a  to acquire Hessian matrix H of the brightness image L on a pixel to pixel basis (Step S 132 ). The Hessian matrix H has three elements of the second order derivative in x direction, the second order derivative in y direction, and the second order derivative in z direction for each pixel. When these elements are defined as Hxx, Hxy, and Hyy respectively, Hxx, Hxy, and Hyy can be represented by: 
         Hxx=ŝ 2*( Dxx**L ) 
         Hyy=ŝ 2*( Dyy**L ) 
         Hxy=ŝ 2*( Dxy**L ) 
     In the above formula, “**” represents convolution; and Dxx is the second order derivative of a Gaussian kenel in X direction, and can be obtained by the following mathematical formula: 
         Dxx= 1/(2*pi*σ̂*4)*(( X .̂2)/ s ̂2−1).*exp(−( X .̂2+ Y .̂2)/(2* s ̂2))
 
     In the above mathematical formula, “s” represents a scale value depending on a size of vessel to be detected. If a vessel having a plurality of sizes is detected, a likelihood V of vessel as described below can be determined with respect to each size of the vessel and maximum likelihood V for each pixel can be selected. “pi” represents a circumference ratio; “X” and “Y” are locations within the kenel; “.*” represents multiplication per an element of the matrix; and “.̂” represents power per an element. 
     Dyy is a second order derivative of a Gaussian kenel in Y direction, and is determined by the transposition of Dxx, as follows: 
     
       
      
       Dyy=Dxx′ 
      
     
     In the above, “′” represents transposition. 
     Dxy is the first order derivative of Gaussian kenel in X direction and Y direction, and is determined in accordance with the following mathematical formula: 
         Dxy= 1/(2*pi*σ̂*6)*( Y.*Y ).*exp(−( X.̂ 2+ Y.̂ 2)/(2* ŝ 2))
 
     The Hessian matrix H is represented, as follows: 
     
       
      
       H=[Hxx Hxy;Hxy Hyy] 
      
     
     Next, the extracting means  101   b  acquire characteristic values λ1 and λ2 of the Hessian matrix H per a pixel (Step S 133 ). Since the Hessian matrix H is a real symmetric matrix, the characteristic values λ1 and λ2 should be real numbers. The characteristic values λ1 and λ2 can be obtained by the following mathematical formula: 
       λ1=0.5*( Dxx+Dyy+tmp )
 
       λ2=0.5*( Dxx;Dyy−tmp )
 
     In the above mathematical formula, tmp is defined as follows: 
         tmp =sqrt(( Dxx−Dyy ).*( Dxx−Dyy )+4* Dxy.*Dxy ) 
     The extracting means  101   b  extract the vascular region as the likelihood V from the characteristic values λ1 and 22 of each pixel acquired in Step S 133 , based on the following mathematical formula: 
         V= 1−exp(( K .̂2)/2*σ̂2))
 
     In the above mathematical formula, K is defined, as follows: 
         K =sqrt(λ1.*λ1+λ2λ2.*λ2)
 
     which is also shown in Step S 134 . In the above formula, “σ” is an adjustment coefficient, and “sqrt ( )” means a square root of each element. 
     If the vascular region is represented by two values, the processing unit  101  can perform binarization using a threshold of th1. In other words, the binarization can be performed, as follows: 
         V= 0 if  V&lt;th 1 
         V= 1 else 
     Effect of Embodiment 
     As described above, in accordance with the diagnostic apparatus  100  directed to Embodiment of the present invention, the processing unit  101  is performed such that the separating means  101   a  separate the captured image into the brightness component and the color information component; the extracting means  101   b  extract the region to be diagnosed such as the vessel-corresponding region using the brightness component or the color information component of the captured image in order to highlight the likeness of the region; and the extracted result is displayed on the display device  120 . For the reasons, the physician can visually check the screen in which the region to be diagnosed is highlighted, thereby allowing him or her to easily and correctly make a diagnosis. Therefore, diagnostic accuracy can be improved. 
     In accordance with the diagnostic device  100  directed to Embodiment of the present invention, the processing unit  101  displays the reconstructed image on the display device  120 . The reconstructed image is generated by the generating means  101   c  via the processing of combining the extracted result of the region with the background image. The physician is provided with a user interface (UI) to select the background image from the group consisting of (1) the captured image, (2) the grayscale image of the captured image, (3) the contrast-highlighted image of the captured image, and (4) the brightness component-highlighted image that is obtained by separating the brightness component of the captured image into the base component and the detail component and performing highlighting process on the base component and the detail component in a different manner. For the reasons, the physician can dynamically select the display type depending on his/her objective of diagnosis, thereby allowing him or her to even more easily and correctly make a diagnosis. Accordingly, diagnosis accuracy can be further improved. 
     Furthermore, if the brightness component-highlighted image that is obtained by separating a brightness component of the captured image into the base component and the detail component and performing highlighting process on the base component and the detail component in a different manner is selected, the separating means  101   a  perform edge preserving filtering process on the image L corresponding to the brightness in the Lab color space so as to separate the base component and the detail component from each other. In this regard, a bilateral filter may be used as the edge preserving filter. The edge preserving filter which can be used in this step may be a bilateral filter. The detail of the bilateral filter is described in, for example, internet URL (http://en.wikipedia.org/wiki/Bilateral filter (accessed on Sep. 1, 2014). 
     While in Embodiment the captured image is converted from the RGB color space to the Lab color space and then processed, the captured image may be converted from the RGB color space to a HSV (Hue, Saturation, Lightness) color space and then processed. In this case, V component corresponds to the brightness component, and the HS component corresponds to the color information component. The HSV color space is a color space consisting of three components, that is, the HSV color space has hue, saturation (chroma), and value (lightness or brightness). The HSV color space can be also called as HSL (Hue, Saturation, Lightness) color space or HSB (Hue, Saturation, Brightness) color space. 
     The above Embodiment is given to illustrate the scope and spirit of the instant invention. This Embodiment will make apparent, to those skilled in the art, other embodiments and examples. These other embodiments and examples are within the contemplation of the present invention. Therefore, the instant invention should be limited only by the appended claims.
       100  . . . diagnotic apparatus;  101  . . . processing unit;  101   a  . . . separating means;  101   b  . . . extracting means;  101   c  . . . generating means;  110  . . . dermoscope-equipped, image-capturing device;  120  . . . display device;  121  . . . captured image-displaying section;  122  . . . highlight image-displaying section;  123  . . . button of “start to capture image”;  124 ,  125 ,  126  . . . checkbox;  130  . . . input device