JP2010063671A - Image processing method and image processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To output information concerning the shape and size of the disk, cup, rim, and the like of the optic nerve head of an eye as a target of optometry in a more understandable format so that the diagnosis of is easily carried out on the basis of the output information. <P>SOLUTION: A trace of a disk periphery (303) corresponding to the optic nerve head and a trace of a cup periphery (304) corresponding to the recessed area of the optic nerve head are obtained from photographed image data of fundus oculi, polar coordinates of pixels in a polar coordinate system around a reference point in the image corresponding to near the center of the optic nerve head of the eye as the target of optometry is obtained, a polar coordinate development image (300) is obtained by mapping the radius vector and deflection angle of the polar coordinates of the pixels in the axis of ordinate and the axis of abscissa of the two-dimensional orthogonal coordinate system to display and output, and each of the image areas demarcated by the disk periphery and the cup periphery is displayed in a display form identifiable from the other parts in the display and output of the polar coordinate development image (403 and 404). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing method and an image processing apparatus for displaying and outputting a fundus image of an eye to be examined.

  Conventionally, as a technique for diagnosing glaucoma using ophthalmologic imaging data, image processing for evaluating the shape and size of the optic nerve head (hereinafter simply referred to as “nipple” or “nipple”) in a fundus image is known.

  When evaluating the size of the nipple recess through image analysis, a distance ratio between the edge of the nipple recess called “Cup” and the edge of the nipple called “Disc”, the so-called C / D ratio is used. There is (for example, Patent Document 1 below).

In addition, a region in the middle of the disc (Disc) that is a nipple recess and a cup (Cup) that is a nipple margin is called a rim (Rim). Diagnosis of glaucoma by observing the width of the rim by an examiner. There is also a technique to do. Although it is conceivable to automatically determine the boundary between the disc and the cup region of the photographed nipple region by image analysis, it is often performed by the examiner analyzing the photographed image.
Japanese Patent No. 3594468

  In general, the width of the rim of the nipple may be locally narrowed, and it is considered to be important for the diagnosis of glaucoma to find such a unique shape, but the rim is radial. It is difficult to objectively identify a narrowed rim by simply displaying an image near the nipple and comparing the width of the rim while looking at the image and comparing the width of the rim. Met.

  Further, in order to support the diagnosis of glaucoma, a technique is conventionally used in which the horizontal axis is plotted as an angle, and the vertical axis is plotted and output as a disc contour height (for example, HRT). The result sheet) simply outputs information such as the height of the disk contour as numerical values or bar graphs, but it is not easy for the examiner to associate the original image with the visual inspection.

  In view of the above problems, an object of the present invention is to output information related to the shape and size of the disc, cup, rim, etc. of the optic papilla of the subject's eye in a format that is easier to understand, and based on this, diagnose glaucoma Is to make it easy to do.

  In order to solve the above problems, in the present invention, from the image data of the captured fundus image, the trajectory of the outer circumference of the disc corresponding to the optic papilla, and the trajectory of the cup outer circumference corresponding to the optic disc recess, The polar coordinates of the pixel in the polar coordinate system centered on the reference point in the image corresponding to the center of the optic nerve head of the eye to be examined are obtained, and the radius and declination of the polar coordinate of this pixel are respectively expressed in the two axes of the two-dimensional orthogonal display coordinate system. A polar coordinate developed image obtained by mapping to the image is generated, displayed and output, and in the display output of the polar coordinate developed image, each image area having the disc outer periphery and the cup outer periphery as a boundary can be distinguished from other parts. Adopted a configuration to display in various display formats.

  According to the above configuration, a polar coordinate developed image obtained by mapping the radius and declination of the polar coordinates of the pixel to the two axes of the two-dimensional orthogonal display coordinate system is generated and displayed, and the polar coordinate developed image is displayed. In the output, since each image area having the boundary between the outer periphery of the disk and the outer periphery of the cup is displayed in a display format that can be distinguished from other parts, the disk, cup of the optic nerve head of the eye to be examined, Information on the shape and size of the middle rim, etc. can be output in a more easily understandable format, and blood vessels are also displayed on the polar coordinate developed image, making it easy to associate with the original image. Based on the above, there is an excellent effect that glaucoma can be easily diagnosed.

  Hereinafter, as an example of the best mode for carrying out the present invention, an ophthalmic measurement apparatus that performs image processing on image data obtained by photographing a fundus of a subject's eye and outputs graphical data relating to the shape of the nipple is output. Examples will be described.

<System configuration>
FIG. 1 shows the configuration of an ophthalmologic measuring apparatus employing the present invention. In FIG. 1, reference numeral 101 denotes a fundus photographing camera from a mechanism for photographing the fundus of a subject's eye (not shown) under a predetermined photographing condition, for example, a fundus camera equipped with an alignment mechanism for determining a photographing distance or the like. Composed. The camera 101 has an image sensor such as a CCD or a CMOS sensor, and outputs fundus image data of the eye to be examined photographed as digital data to the image processing apparatus.

  The image processing apparatus 100 is configured using hardware such as a personal computer. The image processing apparatus 100 includes a CPU 102 that controls the entire system and that constitutes the main body of image processing means that performs image processing to be described later.

  Image processing to be described later is executed using the VRAM (image memory) 104 as a work area. In addition to this, it is assumed that a memory composed of a dynamic RAM or the like is provided as a memory used for system control other than image processing. A program of the CPU 102 for performing image processing to be described later is stored in the ROM 103 or the HDD 105.

  The HDD 105 is used to store captured image data of the eye to be examined, numerical data such as measurement results, or output image data generated by image processing described later.

  A display 107 composed of an LCD, an EL panel, a CRT, or the like is connected to the image processing apparatus 100 as display output means. A user interface screen for controlling image processing of the image processing apparatus 100 is connected to the display 107. Etc. are displayed.

  Further, the image processing apparatus 100 generates image data configured so that the examiner can easily evaluate the shape and size of the disk, cup, rim, and other parts of the nipple of the eye fundus based on the image processing described later. Generate and output to the display 107.

  A network 106 is connected to the image processing apparatus 100 via a network interface (not shown). The image processing apparatus 100 uses an external computer, another image processing apparatus, or an ophthalmologic measurement apparatus for obtaining the above-described captured image data of the subject's eye, numerical data such as measurement results, or output image data generated by image processing described later. Output to etc.

  FIG. 12 shows a rough flow of processing when performing fundus imaging for glaucoma diagnosis and outputting a captured image in this embodiment.

  For example, the camera 101 is positioned with respect to the eye to be examined (not shown) using an operation system and an alignment system according to the fundus camera, and the camera 101 displays an image of the fundus of the eye to be examined according to a specific photographing operation of the examiner. A picture is taken (step S10). In photographing for glaucoma diagnosis, the photographing angle is determined so that the nipple of the fundus of the eye to be examined and its vicinity are at the center of the screen. At this time, preferably, the fundus of the eye to be examined is photographed in stereo. As the stereo photographing means, for example, in the main optical system of the camera 101, a configuration in which left and right parallax images are photographed by opening / closing apertures provided at positions offset to the left and right from the center of the optical axis is used. it can. In the following, stereo image data is also shown.

  The image processing apparatus 100 captures image data of the fundus of the eye to be examined photographed by the camera 101 (step S11) and displays it on the display 107 in a predetermined display format (step S12).

  The cup and disc area of the nipple portion of the fundus of the eye to be examined in the photographed image data are specified using the cup outer circumference obtaining unit 110 and the disk outer circumference obtaining unit 111 (step S13).

  Although the cup outer periphery acquisition unit 110 and the disk outer periphery acquisition unit 111 may be configured by image recognition software of the CPU 102, in this embodiment, the cup outer periphery acquisition unit 110 and the disk outer periphery acquisition unit 111 are a keyboard (not shown). And an operation unit hardware such as a mouse, a digitizer pad, a pointing device, etc., and the examiner operates these operation unit hardware while observing an image of the fundus oculi to be inspected displayed on the display 107 to display the display 107. The region determined to be the outer periphery of the cup and the outer periphery of the disc in the image of the fundus oculi displayed on the eye is specified. As a specific operation, for example, an operation of drawing a locus in a fundus image with a pointing device can be considered.

  When the cup outer periphery and the disc outer peripheral area are specified, the examiner designates a display method using the operation means such as the keyboard and the pointing device (step S14), and the image processing apparatus 100 responds to the designated display method. Thus, image data to be displayed is generated and displayed on the display 107.

<Image processing and display control>
Next, image processing and display control in the above configuration will be described.

  In the image processing for the fundus photographed image of the present embodiment, a polar coordinate system centered on a reference point (for example, a polar coordinate system centered on a predetermined reference point in the outer periphery of the disk) in the image that is substantially equivalent to the center of the nipple of the eye to be examined. A display output method is used in which the polar coordinates of the pixel in the pixel are obtained, and the polar coordinates (radial radius, declination) of the pixel are mapped (mapped) to the two axes of the two-dimensional orthogonal display coordinate system and displayed graphically. The display coordinate system of this display output system is, for example, a two-dimensional orthogonal display coordinate system having an angle on the horizontal axis and a moving radius (distance) on the vertical axis as will be described later (FIGS. 6 to 11).

  In the present embodiment, various display conversion processes useful for glaucoma diagnosis, for example, in such a display coordinate system will also be described.

  2 (a), 2 (b), 3 (a), and 3 (b) are a stereo pair image of the right optic nerve head of the eye to be inspected by the camera 101 (step S10 in FIG. 12), and A pair image of the optic papilla of the right eye of the optometry is schematically shown. As shown in the upper part of FIGS. 2A and 3A, the left (201) and right (202) stereo images so that the left side of the image corresponds to the temporal side and the right side corresponds to the nose side. (In each of the following figures, the temporal side and the nose side are displayed as needed in the figure).

  2 and 3, reference numeral 203 indicates the outer periphery of the disc area of the photographed nipple, and 204 indicates the outer periphery of the cup area of the imaged nipple. An intermediate portion between the disk area outer periphery 203 and the cup area outer periphery 204 is an area called a rim, and generally has a shape that rises slightly higher than the outside of the disk area outer periphery 203. As one of the criteria for diagnosing glaucoma, there is a case where shape evaluation is used to determine whether or not the width of the rim portion is (partly) narrow.

  The CPU 102 displays the stereo image acquired from the camera 101 (step S11 in FIG. 12) as shown in FIGS. 2 (a), 2 (b) and FIGS. Step S12). In that case, it can be presented to the examiner by stereo display using a predetermined stereo display method or the like.

  The image processing of the present embodiment is performed for each of the left and right stereo images taken as shown in FIGS. 2A, 2B, 3A, and 3B, and the result can be displayed on both. However, only the processing for one of the stereo images will be described below.

  For the right eye and the left (or right) stereo image of the left eye taken as shown in FIG. 2 (a) or (b), FIG. 3 (a) or (b), the examiner The positions of the cup area outer circumference 204 and the disk area outer circumference 203 are designated using the cup outer circumference obtaining means 110 and the disk outer circumference obtaining means 111. Specifically, this designation is performed by marking the locus on the right eye and the left (or right) stereo image of the right eye and the left eye using the pointing device constituting these acquisition means 110 and 111. (Step S13 in FIG. 12).

  The determination of the outer periphery 204 of the cup area and the outer periphery 203 of the disk area is performed by image recognition as described in Patent Document 1 (for example, by extracting depth information from a stereo photographed image and tracing the locus of parts having substantially the same depth. In the following, it is assumed that the examiner designates the cup area outer circumference 204 and the disk area outer circumference 203 using the cup outer circumference obtaining unit 110 and the disk outer circumference obtaining unit 111.

  FIGS. 4A and 5A show the display state on the display 107 when the examiner finishes specifying the cup area outer periphery 204 and the disk area outer periphery 203. FIG. In the example of FIGS. 4A and 5A, the cup area outer circumference 204 and the disk area outer circumference 203 designated by the examiner are displayed by bold lines, and the middle rim and the center cup area are displayed on other images. Display using a display format that can be distinguished from the part, for example, highlighting using different colors and pattern displays is performed. The highlighting using these different colors and pattern displays is preferably a semi-transparent display so that the image of the nipple and fundus blood vessels 205 can be visually recognized.

  The CPU 102 controls the cup outer periphery acquisition unit 110 and the disk outer periphery acquisition unit 111 to read the operation of the examiner's pointing device and the like, and to control the display on the display 107, thereby FIG. 4 (a) and FIG. A display as shown in a) is performed.

  The trajectory of the cup area outer periphery 204 and the disk area outer periphery 203 specified by the examiner is, for example, a VRAM 104 or other as a column (pointer data sequence) of pixel addresses (xy coordinate data in two-dimensional orthogonal coordinates) on the trajectory. Are stored in a storage area secured in a predetermined area of a memory such as a RAM.

Subsequently, as shown in FIGS. 4B and 5B, the CPU 102 obtains the center (polar coordinate center: or polar coordinate origin) O of the polar coordinate system that is the basis of the image processing of this embodiment. To find this polar center,
(A) The center of gravity of the disk area is obtained two-dimensionally by calculation.

  (B) Map data of fundus depth information is created from the stereo image, and the deepest point is the center.

(C) An examiner (operator) arbitrarily designates using a pointing device or the like.
Such a method can be considered. In this embodiment, since a stereo image is acquired, a method of creating a fundus depth map from the stereo image and setting the deepest point as the polar coordinate center O as shown in (b) is adopted. According to this method, for example, rather than simply obtaining a representative point such as the center of gravity of the disk area by a two-dimensional calculation, a representative point that more closely matches the three-dimensional shape of the nipple of the subject's eye is set to the center of the nipple It can be obtained as the polar coordinate center O.

  When the polar coordinate center O is obtained by calculating the center of gravity, instead of obtaining the center of gravity of the disk area (inside of the disk area outer periphery 204), the center of gravity of the cup area (inside of the outer periphery of the cup area 203) is obtained, and this is determined as polar coordinates. It may be the center O.

  Subsequently, the CPU 102 places a virtual line segment around the polar coordinate center O obtained as described above, rotates the virtual line segment, and sequentially acquires each pixel data on the virtual line segment, thereby obtaining polar coordinates. Conversion into pixel data in a polar coordinate system centered on the center O is performed. 4 (b) and 5 (b), respectively, put virtual line segments OA in the images of the right eye and the left eye, which are represented by OB, OC, OD, OE, The pixel data passing through these virtual line segments is re-mapped into a table memory representing the polar coordinate system centered on the center O, and converted to the polar coordinate system. Can do.

  Note that virtual line segments OA, OB, OC, OD, OE, and OF in FIGS. 4B and 5B are shown in the display example of FIG. 7 described later. It is consistent with the guideline position.

  Specifically, for example, by generating a pointer array (table) in which the address storing pixel data in the xy coordinate system before conversion is stored in a table memory representing the polar coordinate system, Data conversion can be performed.

  4 (b) and 5 (b) are simplified and short, but actually have a length sufficient to cover the entire range in which pixel data exists, and virtual line segments The rotation of OA, OB, OC, OD, OE, and OF is performed by a minute angle (for example, sufficient resolution can be secured at the peripheral portion of the image).

  In this embodiment, the polar coordinate conversion image data (the content of the pixel data is the luminance or density data of the pixel as before the conversion) is plotted on the horizontal axis as shown in FIGS. The angle is displayed using a two-dimensional orthogonal display coordinate system with the radius (distance) on the vertical axis. In the present embodiment, such a display image is referred to as a polar coordinate developed image for convenience.

  In the display of the polar coordinate developed image, various different displays as shown in FIGS. 6 to 11 can be performed using the display 107. In the polar coordinate development images 300 of FIGS. 6 to 11, pixel data subjected to polar coordinate conversion as described above is displayed using a two-dimensional orthogonal display coordinate system in which an angle is taken on the horizontal axis and a moving radius (distance) is taken on the vertical axis. ing. 6 to 11, the side close to the polar coordinate center is set downward in the figure.

  In the display of FIG. 6, a cup area outer periphery 304 and a disk area outer periphery 303 are contours corresponding to the cup area outer periphery 204 and the disk area outer periphery 203 in the normal display coordinate system (orthogonal coordinate system: for example, FIGS. 2 and 3), reference numeral 305. Is an image of a fundus blood vessel.

  In FIG. 6, the middle part of the cup area outer periphery 304 and the disk area outer periphery 303 corresponds to the rim part important in the diagnosis of glaucoma, and is thus displayed as a polar coordinate developed image such that the rim part continues in the horizontal direction. By doing so, the examiner can more clearly know the dimensional distribution of the part of the rim between the cup area outer periphery 304 and the disk area outer periphery 303 than the display in the original orthogonal coordinate system.

  The display of the polar coordinate development image in FIG. 6 is a display of pixel data that has been subjected to polar coordinate conversion as described above, using a two-dimensional orthogonal display coordinate system in which the horizontal axis represents the angle and the vertical axis represents the moving radius (distance). is there. The display density (or luminance) of the pixels corresponding to the fundus region, blood vessels, nipples, etc. is a two-dimensional orthogonal coordinate system with the vertical and horizontal (xy) distances shown in FIGS. Hereinafter, it is the same as the display in a normal two-dimensional orthogonal coordinate system), so to speak, it can be said that the pixels are expanded and deformed in an easily understandable manner around the nipple.

  If the display of the polar coordinate development image as shown in FIG. 6 is the basic display form (basic display mode) of the present embodiment, different display forms (display modes) as shown in FIGS. Conceivable.

  7 is displayed on the fundus image displayed in the basic display form in FIG. 6 on the virtual line segments OA, OB, O- in FIGS. 4B and 5B. A guideline is placed at a position where C, OD, OE, and O-F are placed, and is indicated by a broken line. Here, the outer ends of each guideline are shown using the same symbols A to F (the polar coordinate center O is on the horizontal axis).

  When the display form (display mode) as shown in FIG. 7 is adopted, after the examiner designates the cup area outer circumference 204 and the disk area outer circumference 203 as shown in FIG. 4 (a) or FIG. 5 (a) (or At the same time, imaginary line segments OA, OB, OC, OD, OE, and OF are converted into normal two-dimensional shapes as shown in FIG. 4B or 5B. Displayed as a guideline in the Cartesian coordinate system and displayed in the display form shown in FIG. 4B or 5B, or displayed in the display form shown in FIG. 4B or 5B And display according to the display form (display mode) of FIG.

  By performing the display as shown in FIG. 7, the correspondence between the display part in the normal two-dimensional orthogonal coordinate system and the display part in the polar coordinate developed image can be presented to the examiner very easily.

  The display form (display mode) in FIG. 8 highlights parts corresponding to the cup area 404 and the rim area 403 on the fundus image displayed in the basic display form in FIG. Such an emphasis display is an emphasis display using a different color or pattern display so that it can be distinguished from other captured image portions as described with reference to FIGS. 4A and 5A. The part is preferably translucently displayed so that an image of the nipple and fundus blood vessel 205 can be visually recognized. It should be noted that the positions of the cup area outer periphery 304 and the disk area outer periphery 303 are made to coincide with the positions of the cup area outer periphery 204 and the disk area outer periphery 203 specified by the examiner in FIGS. 4 (a) and 5 (a).

  As shown in FIG. 8, by using a display form (display mode) with emphasis on the rim area 403 or further the cup area 404, a basic display form (basic display mode) as shown in FIG. Rather than representing the image using only the density (or luminance) of the original pixel, it is possible to present the shape of the rim region 403 or the cup region 404 that is clearly determined in accordance with the examiner's region designation.

  The display form (display mode) in FIG. 9 is a composite display form (composite display mode) of the display form (display mode) in FIG. 7 and the display form (display mode) in FIG. 8, and has been described with reference to FIG. The guideline is displayed and the rim region 403 and the cup region 404 described with reference to FIG. According to such a composite display mode (composite display mode), the position in the circumferential direction can be clearly presented by the guideline display, and the rim region 403 determined according to the region designation of the examiner, or further the cup. The shape of the region 404 can be clearly presented.

  In FIGS. 8 and 9, the highlight color to be given to the rim area 403 and the cup area 404 corresponds to the outer periphery designation shown in FIGS. 4 (a) and 5 (a). By matching the highlight color used for the rim area and the cup area, the correspondence between the image areas can be read more easily.

  The display form (display mode) in FIG. 10 displays an image obtained by modifying the display image in the basic display form (basic display mode) in FIG.

  The examiner specifies by moving one line having a width of one pixel along the vertical direction of the display image in the basic display form (basic display mode) of FIG. 6 in the vertical direction as shown in FIG. The image can be deformed so that the specific boundary line is displayed as a straight line on the display 107. As a part to be displayed as a straight line on the display 107 when the image is deformed, for example, the locus of the cup area outer periphery 304 or the disk area outer periphery 303 specified by the examiner can be considered.

  In the example of FIG. 10, the cup region outer periphery 304 is displayed as a straight line on the display 107, and one line having a width of one pixel along the vertical direction in the drawing is translated in the vertical direction. . When the cup region outer periphery 304 is displayed as a straight line by such deformation of the display image, the rim region 503 and the cup region 504 are deformed as illustrated.

  The rim region 503 and the cup region 504 are the boundary between them, and are lined up and down via the cup region outer periphery 304 displayed as a straight line, so the examiner can easily change the width of the rim region 503 and the cup region 504. Can be read. For example, the change (distribution) of the width of the rim region 503 useful for the diagnosis of glaucoma can be read as a kind of graph display according to the display as shown in FIG. 10, and the examiner can read the width of the rim region 503 at a glance. Change (distribution) can be recognized.

  The black areas at the top and bottom of FIG. 10 are portions having no pixel data generated by moving one line having a width of one pixel along the vertical direction in the drawing up and down, and are shown in FIG. As shown in the figure, the portion excluding the one line translated in the uppermost direction and the one line translated in the lowermost direction is filled with black (or another display color) and displayed. By such display, it is possible to perform display so that pixel information of one vertical line is not lost. However, an image whose upper and lower sides are trimmed may be displayed so as not to display a portion without such pixel data. Also, what is indicated by reference numeral 505 is a fundus blood vessel in the image.

  The display in FIG. 11 shows the disc area designated by the examiner when three-dimensional measurement can be performed from stereo imaging data (for example, FIGS. 2 and 3) and depth information of each part of the fundus can be obtained. Depth information (difference from the reference point of three-dimensional measurement) of the portion of the locus of the outer periphery (for example, 203 in FIG. 4A, 203 in FIG. 5A, 303 in FIG. 10) and taking the angle on the horizontal axis. It is a graph display.

  The graph information of the depth information of the outer periphery (203, 303) of the disk area as shown in FIG. 11 is displayed on the display 107 with the left and right widths aligned with the image display in the display form (display mode) of FIG. Thus, useful information can be presented to the examiner. That is, the examiner can easily grasp the change (distribution) of the width of the rim area 503 and simultaneously change the height (distribution) of the outer circumference (203, 303) of the disk area corresponding to the edge of the rim area 503. It can be easily read, and the shape of the rim region 503 can be grasped three-dimensionally and three-dimensionally.

  FIGS. 2 to 11 show various captured images or images in which guide lines are added, highlighted, or deformed in various display forms (display modes). These images are sequentially displayed on the display 107. In addition, the captured image and the display image in various display forms (display modes) can be displayed on the display 107 at the same time (tiled window display, Any simultaneous display method such as a superimposed window display may be used).

  FIG. 13 shows a more detailed flow of the image processing procedure in the image processing system of the present embodiment. FIG. 13 shows both the operation of the examiner and the image processing of the image processing apparatus 100, but the program of the CPU 102 for executing the image processing as the processing subject of the image processing apparatus 100 is stored in the ROM 103 or the HDD 105. I shall keep it. In addition, about the procedure and process already demonstrated in FIG. 12, only a corresponding step number is described below and the overlapping description is abbreviate | omitted.

  In step S20 in FIG. 13, as described in step S10 in FIG. 12, image data of the eye to be examined is captured and acquired by the camera 101. Note that the image data acquired as a processing target at this time does not necessarily have to be captured by the camera 101 each time, but may be captured in the past and stored in a filing system configured using the HDD 105 or the like. .

  In step S21, the photographed fundus image is displayed in a conventional display format. Subsequently, in step S22, it is determined whether or not the above-described polar coordinate development image display according to the present invention is performed. When the polar coordinate development image display according to the present invention is not performed, the process returns to step S21, and, for example, the process of displaying the photographed image or the image stored in the HDD 105 or the like as it is is performed as usual.

  When the polar coordinate development image display according to the present invention is performed in step S22, the process proceeds to step S23, and the outer peripheries of the cup area and the disk area are determined. At this time, for example, the examiner controls the cup outer periphery acquisition unit 110 and the disk outer periphery acquisition unit 111 to specify the outer track of the cup region and the disk region (or an image by a method described in Patent Document 1). The outer track of the cup area and the disk area is determined by the recognition process).

  In step S24, a reference point for polar coordinate development processing, that is, a polar coordinate center (origin) O is determined. Here, as described above, (a) the center of gravity of the disc area is calculated two-dimensionally by calculation, (b) a fundus depth map is created from the stereo image, and the deepest point is the center, (c) An operator (operator) can arbitrarily specify using a pointing device or the like.

  In step S25, the display format shown in FIGS. 6 to 11 (various display modes described in FIGS. 2 to 11 or one or a combination of display modes) is selected. Here, only one display format may be selected, or selection such that display in any or all display formats is performed on the display 107 may be allowed.

  In step S26, it is determined whether or not to generate a polar coordinate development image based on the designation of the outer periphery of the cup area and the disk area in step S23, the determination of the polar coordinate center O in step S24, and the display format selected in step S25. When no polar coordinate development image is generated, the process returns to step S21, and the conventional image display is performed.

When generating a polar coordinate development image, the processing contents of polar coordinate development are determined in step S28, necessary display control parameters are determined, etc., and image processing for generating a polar coordinate development image is performed. In the example of FIG. Prior to S28,
In step S27, it is determined whether the fundus image for generating the polar coordinate developed image is that of the right eye or that of the left eye. When the fundus image is displayed on the display 107, the position of the temporal / nose side is taken to the right or the left of the display 107 depending on the left and right eyes (the direction in which the left eye and the right eye are deployed) On the contrary, it is preferable to select “take”.

  Therefore, in the control example of FIG. 13, it is determined in step S28 whether the fundus image to be displayed as the polar coordinate developed image is that of the right eye or that of the left eye, and the polar coordinate developed image is displayed according to the result. In this case, the left / right side of the display 107 on the display 107 is determined to be positioned. Here, when using a fundus image filed in the HDD 105 or the like, if the left and right identification information of the eye to be examined is recorded in association with the fundus image, the information is read and used. If the left and right identification information of the eye to be examined in the fundus image is missing or cannot be read, the examiner (or operator) may be requested to input.

  Next, in step S28, the determined polar coordinate development process is performed, and in step S29, the fundus image developed by polar coordinates is displayed by controlling the display 107. In step S29, the fundus image is displayed by one or a combination of the display modes described in FIGS.

  For example, by performing image processing as shown in FIG. 13, an image of the optic nerve head on the fundus of the eye to be examined is captured, and an image display format is appropriately selected, and a region near the optic nerve head around the polar coordinate developed image, For example, the peripheral edge of the cup or disk and the rim shape and size distribution in the middle can be displayed in an easily understandable manner.

  Also, if the polar coordinate developed image and the original image are displayed in parallel on the display and the position is specified on one image, the point corresponding to the specified position on the other image is shown, and then the polar coordinate developed image and the original image are displayed. It becomes easier to understand the correspondence.

  In the above, an example in which a polar coordinate development image is displayed and output using the display 107 has been described. However, an image displayed on the display 107 can also be output using an image output unit such as a printer, and a network. The data can also be transmitted to another computer or image processing apparatus via 106.

  The present invention can be implemented in an image processing apparatus such as a fundus camera, an ophthalmologic measurement apparatus, or a filing apparatus that performs image processing for displaying and outputting a fundus image of a subject's eye.

1 is a block diagram showing a configuration of an image processing system adopting the present invention. FIG. 2 is an explanatory diagram showing a stereo image of the right eye of the subject eye near the optic papilla in the image processing system of FIG. 1. FIG. 3 is an explanatory diagram showing a stereo image of the left eye of the subject eye near the optic papilla in the image processing system of FIG. 1. It is explanatory drawing which showed the image process with respect to the image of the optic nerve head of the right eye to be examined in the image processing system of FIG. It is explanatory drawing which showed the image process with respect to the image of the optic nerve head of the left eye to be examined in the image processing system of FIG. It is explanatory drawing which showed the polar coordinate expansion | deployment image of the optic disc of the right eye to be examined in the image processing system of FIG. It is explanatory drawing which showed the different display form of the polar coordinate expansion | deployment image of the optic disc of the right eye to be examined in the image processing system of FIG. It is explanatory drawing which showed the further different display form of the polar coordinate expansion | deployment image of the optic nerve head of the right eye to be examined in the image processing system of FIG. It is explanatory drawing which showed the further different display form of the polar coordinate expansion | deployment image of the optic nerve head of the right eye to be examined in the image processing system of FIG. It is explanatory drawing which showed the further different display form of the polar coordinate expansion | deployment image of the optic nerve head of the right eye to be examined in the image processing system of FIG. FIG. 2 is an explanatory diagram showing a display form of height information on the outer periphery of the disc area of the optic papilla of the right eye to be examined in the image processing system of FIG. 1. It is the flowchart figure which showed the flow of the image processing in the image processing system of FIG. It is the flowchart figure which showed the flow of the image processing in the image processing system of FIG. 1 in detail.

Explanation of symbols

O Polar coordinate center 100 Image processing apparatus 101 Camera 102 CPU
103 ROM
105 HDD
106 Network 107 Display 110 Cup outer periphery acquisition means 111 Disc outer periphery acquisition means 203, 303 Disk region outer periphery 204, 304 Cup region outer periphery 205, 305, 505 Fundus blood vessel 300 Polar coordinate developed image 304 Cup region outer periphery 403 Rim region 404 Cup region

Claims (6)

From the image data of the imaged fundus image, obtain the trajectory of the outer circumference of the disc corresponding to the optic disc and the trajectory of the outer circumference of the cup corresponding to the concave portion of the optic disc,
Find the polar coordinates of the pixel in the polar coordinate system centered on the reference point in the image corresponding to the center of the optic nerve head of the eye to be examined,
A polar coordinate developed image obtained by mapping the radius and declination of the polar coordinates of the pixel to the two axes of the two-dimensional orthogonal display coordinate system is generated and displayed, and the display of the polar coordinate developed image is performed by the disk. A fundus image processing method characterized by displaying each image area having an outer periphery and the cup outer periphery as a boundary in a display format distinguishable from other parts.   The fundus image processing method according to claim 1, wherein the outer periphery of the disc and the trajectory of the outer periphery of the cup are acquired based on depth information of image data of a fundus image captured in stereo.   3. The fundus image processing method according to claim 1, wherein the normal display output for displaying the fundus image almost as it is corresponds to the trajectory of the outer circumference of the disc corresponding to the acquired optic papilla and the optic papilla recess. Color-coded display is performed on the image area bounded by the locus of the cup circumference, and in the display output of the polar coordinate developed image, the locus of the disk circumference corresponding to the optic papilla and the cup circumference corresponding to the optic papilla recess A fundus image processing method, wherein the same color-coded display as that in the normal display output is performed on an image region having the trajectory of the image as a boundary.   The fundus image processing method according to any one of claims 1 to 3, wherein depth information of the captured fundus is detected from a stereo imaged fundus image, and is determined from the depth information. A fundus image processing method, wherein polar coordinates of a pixel are obtained using a deepest point as the reference point.   The fundus image processing method according to any one of claims 1 to 4, wherein a boundary line corresponding to the outer periphery of the cup or the outer periphery of the disk is displayed as a straight line when the polar coordinate development image is displayed and output. A fundus image processing method characterized by displaying image data by moving parallel to an axial direction in which the radius of a two-dimensional orthogonal display coordinate system is associated. In the fundus image processing apparatus for executing the fundus image processing method according to any one of claims 1 to 5,
Image processing means for performing the polar coordinate expansion process;
A fundus image processing apparatus comprising display output means for displaying the polar coordinate development image generated by the image processing means.

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