Image processing method, program, ophthalmic device, and choroidal vessel image generating method

Abstract

To reduce impact from a retinal vessel on analysis of a choroidal vessel.SOLUTION: A method for processing an image includes a step of enhancing a choroidal vessel in a first fundus image in which the choroidal vessel is relatively made to be conspicuous by reading image data of the first fundus image (R color fundus image) and a second fundus image (G color fundus image), extracting a retinal vessel from the second fundus image, removing a retinal vessel from the first fundus image, thereby acquiring a choroidal vessel image in which the choroidal vessel is made to be conspicuous.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology of the present disclosure relates to an image processing method, a program, an ophthalmic apparatus, and a choroidal blood vessel image generating method. [Background technology]

[0002] Patent No. 5739323 discloses enhancing retinal vascular features. Summary of the Invention

[0003] An image processing method according to a first aspect of the disclosed technology includes generating a choroidal blood vessel image based on a first fundus image obtained by photographing the fundus with first light having a first wavelength and a second fundus image obtained by photographing the fundus with second light having a second wavelength that is shorter than the first wavelength.

[0004] A program according to a second aspect of the technique of the present disclosure causes a computer to execute the image processing method according to the first aspect.

[0005] An ophthalmic apparatus according to a third aspect of the disclosed technology is an ophthalmic apparatus comprising a storage device that stores a program for causing a processor to execute an image processing method, and a processing device that executes the image processing method by executing the program stored in the storage device, wherein the image processing method is the image processing method of the first aspect.

[0006] A choroidal vascular image generating method according to a fourth aspect of the disclosed technique includes the steps of: acquiring a fundus image by photographing the fundus with light having a wavelength of 630 nm or more; extracting retinal blood vessels from the fundus image; and generating a choroidal vascular image by erasing the retinal blood vessels from the fundus image. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram of an ophthalmology system 100. [Figure 2] 1 is a schematic diagram showing the overall configuration of an ophthalmologic apparatus 110. FIG. [Figure 3] FIG. 2 is a block diagram of the electrical configuration of the management server 140. [Figure 4] FIG. 2 is a functional block diagram of a CPU 162 of a management server 140. [Figure 5] 10 is a flowchart of an image processing program. [Figure 6A] FIG. 10 is a diagram showing a first fundus image (red-colored fundus image). [Figure 6B] FIG. 10 is a diagram showing a second fundus image (green fundus image). [Figure 6C] FIG. 10 is a diagram showing a choroidal vessel image in which choroidal vessels are relatively prominent. [Figure 6D] FIG. 10 is a diagram showing a choroidal vessel image in which choroidal vessels are enhanced. [Figure 7] FIG. 3 shows a display screen 300 in choroidal vessel analysis mode when the fundus of a patient is photographed for the first time. [Figure 8] FIG. 3 is a diagram showing a display screen 300 in choroidal vessel analysis mode when a patient's fundus is photographed a total of three times on different days. [Figure 9] 13 is a flowchart of an image processing program according to a seventh modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For convenience of explanation, a scanning laser ophthalmoscope will be referred to as an "SLO" below.

[0009] The configuration of an ophthalmologic system 100 will be described with reference to Fig. 1. As shown in Fig. 1, the ophthalmologic system 100 includes an ophthalmologic apparatus 110, an axial length measurement apparatus 120, a management server apparatus (hereinafter referred to as "management server") 140, and an image display apparatus (hereinafter referred to as "image viewer") 150. The ophthalmologic apparatus 110 acquires fundus images. The axial length measurement apparatus 120 measures the axial length of a patient. The management server 140 stores a plurality of fundus images and axial lengths obtained by photographing the funduses of a plurality of patients using the ophthalmologic apparatus 110, in association with the patient IDs. The image viewer 150 displays the fundus images acquired by the management server 140.

[0010] The ophthalmologic apparatus 110, the axial length measurement apparatus 120, the management server 140, and the image viewer 150 are connected to one another via a network . In addition, other ophthalmic devices (examination devices for visual field measurement, intraocular pressure measurement, etc.) and diagnostic support devices that perform image analysis using artificial intelligence may be connected to the ophthalmic device 110, the axial length measurement device 120, the management server 140, and the image viewer 150 via the network 130.

[0011] Next, the configuration of the ophthalmologic apparatus 110 will be described with reference to Fig. 2. As shown in Fig. 2, the ophthalmologic apparatus 110 includes a control unit 20, a display / operation unit 30, and an SLO unit 40, and captures an image of the posterior segment (fundus) of the subject's eye 12.

[0012] The control unit 20 includes a CPU 22, a memory 24, and a communication interface (I / F) 26. The display / operation unit 30 is a graphic user interface that displays captured images and receives various instructions including instructions for capturing images, and includes a display 32 and a touch panel 34.

[0013] The SLO unit 40 includes a light source 42 of G light (green light: wavelength 530 nm), a light source 44 of R light (red light: wavelength 650 nm), and a light source 46 of IR light (infrared (near-infrared light): wavelength 800 nm). The light sources 42, 44, and 46 emit their respective lights in response to commands from the control unit 20. The light source of the R light is a laser light source that emits visible light with a wavelength of 630 nm to 780 nm, and the light source of the IR light is a laser light source that emits near-infrared light with a wavelength of 780 nm or more.

[0014] The SLO unit 40 includes optical systems 50, 52, 54, and 56 that reflect or transmit light from the light sources 42, 44, and 46 to guide the light along a single optical path. The optical systems 50 and 56 are mirrors, and the optical systems 52 and 54 are beam splitters. G light is reflected by the optical systems 50 and 54, R light is transmitted through the optical systems 52 and 54, and IR light is reflected by the optical systems 52 and 56 to guide the light along a single optical path.

[0015] The SLO unit 40 includes a wide-angle optical system 80 that two-dimensionally scans light from the light sources 42, 44, and 46 over the posterior segment (fundus) of the subject's eye 12. The SLO unit 40 includes a beam splitter 58 that reflects G light from the posterior segment (fundus) of the subject's eye 12 and transmits all light other than G light. The SLO unit 40 includes a beam splitter 60 that reflects R light from the light that has passed through the beam splitter 58 and transmits all light other than R light. The SLO unit 40 includes a beam splitter 62 that reflects IR light from the light that has passed through the beam splitter 60. The SLO unit 40 includes a G light detecting element 72 that detects G light reflected by the beam splitter 58, an R light detecting element 74 that detects R light reflected by the beam splitter 60, and an IR light detecting element 76 that detects IR light reflected by the beam splitter 62.

[0016] The wide-angle optical system 80 includes an X-direction scanning device 82 composed of a polygon mirror that scans light from the light sources 42, 44, and 46 in the X direction, a Y-direction scanning device 84 composed of a galvanometer mirror that scans light in the Y direction, and an optical system 86 including a slit mirror and an elliptical mirror (not shown) that widens the angle of the scanned light. The optical system 86 increases the field of view (FOV) of the fundus to a larger angle than conventional techniques, enabling a wider fundus area to be imaged than conventional techniques. Specifically, it is possible to image a wider fundus area with an external light irradiation angle of approximately 120 degrees from outside the subject's eye 12 (approximately 200 degrees, with the center O of the eyeball of the subject's eye 12 as the reference position, and the internal light irradiation angle that can be substantially imaged by irradiating the fundus of the subject's eye 12 with scanning light). The optical system 86 may be configured using a group of multiple lenses instead of a slit mirror and an elliptical mirror. Each of the scanning devices, the X-direction scanning device 82 and the Y-direction scanning device 84, may be a two-dimensional scanner configured using MEMS mirrors.

[0017] When a system including a slit mirror and an elliptical mirror is used as optical system 86, a configuration using a system using an elliptical mirror as described in International Application No. PCT / JP2014 / 084619 or International Application No. PCT / JP2014 / 084630 may be used. The disclosures of International Application No. PCT / JP2014 / 084619 filed on December 26, 2014 (International Publication No. WO2016 / 103484) and International Application No. PCT / JP2014 / 084630 filed on December 26, 2014 (International Publication No. WO2016 / 103489) are each incorporated herein by reference in their entirety.

[0018] When the ophthalmologic apparatus 110 is placed on a horizontal plane, the horizontal direction is defined as the "X direction," the vertical direction relative to the horizontal plane is defined as the "Y direction," and the direction connecting the center of the pupil of the anterior segment of the subject's eye 12 and the center of the eyeball is defined as the "Z direction." Therefore, the X direction, Y direction, and Z direction are perpendicular to each other.

[0019] A color fundus image is obtained by simultaneously photographing the fundus of the subject's eye 12 with G light and R light. More specifically, the control unit 20 controls the light sources 42 and 44 to emit light simultaneously, and the wide-angle optical system 80 scans the fundus of the subject's eye 12 with the G light and R light. The G light reflected from the fundus of the subject's eye 12 is detected by the G light detection element 72, and image data of a second fundus image (G-color fundus image) is generated by the image processing unit 182. Similarly, the R light reflected from the fundus of the subject's eye 12 is detected by the R light detection element 74, and image data of a first fundus image (R-color fundus image) is generated by the CPU 22 of the ophthalmic device 110. When IR light is irradiated, the IR light reflected from the fundus of the subject's eye 12 is detected by the IR light detection element 76, and image data of the IR fundus image is generated by the CPU 22 of the ophthalmic device 110.

[0020] The CPU 22 of the ophthalmologic apparatus 110 mixes the first fundus image (red fundus image) and the second fundus image (green fundus image) at a predetermined ratio to display a color fundus image on the display 32. Note that instead of the color fundus image, the first fundus image (red fundus image), the second fundus image (green fundus image), or an IR fundus image may be displayed. Image data of the first fundus image (R-colored fundus image), image data of the second fundus image (G-colored fundus image), and image data of the IR fundus image are sent from the ophthalmologic apparatus 110 to the management server 140 via the communication IF26.

[0021] In this way, the fundus of the test eye 12 is photographed simultaneously using G light and R light, so that each position in the first fundus image (R-color fundus image) and the corresponding position in the second fundus image (G-color fundus image) are the same positions on the fundus.

[0022] The axial length measurement device 120 in FIG. 1 has two modes, a first mode and a second mode, for measuring the axial length of the subject's eye 12, which is the length in the axial direction (Z direction). In the first mode, light from a light source (not shown) is guided to the subject's eye 12, and then interference light between reflected light from the fundus and reflected light from the cornea is received, and the axial length is measured based on an interference signal indicating the received interference light. In the second mode, ultrasound (not shown) is used to measure the axial length. The axial length measurement device 120 transmits the axial length measured in the first mode or the second mode to the management server 140. The axial length may be measured in both the first mode and the second mode. In this case, the average of the axial lengths measured in both modes is transmitted to the management server 140 as the axial length. The axial length is stored as patient information in the management server 140 as part of the patient data, and is also used for fundus image analysis.

[0023] Next, the configuration of the management server 140 will be described with reference to Fig. 3. As shown in Fig. 3, the management server 140 includes a control unit 160 and a display / operation unit 170. The control unit 160 includes a computer including a CPU 162, a memory 164 which is a storage device, and a communication interface (I / F) 166. An image processing program is stored in the memory 164. The display / operation unit 170 is a graphic user interface which displays images and accepts various instructions, and includes a display 172 and a touch panel 174.

[0024] The configuration of the image viewer 150 is the same as that of the management server 140, and therefore a description thereof will be omitted.

[0025] Next, various functions realized by the CPU 162 of the management server 140 executing the image processing program will be described with reference to Fig. 4. The image processing program has an image processing function, a display control function, and a processing function. When the CPU 162 executes the image processing program having these functions, the CPU 162 functions as an image processing unit 182, a display control unit 184, and a processing unit 186, as shown in Fig. 4.

[0026] Next, the image processing by the management server 140 will be described in detail with reference to Fig. 5. The image processing shown in the flowchart of Fig. 5 is realized by the CPU 162 of the management server 140 executing an image processing program.

[0027] The image processing program starts when image data of a fundus image obtained by photographing the fundus of the subject's eye 12 using the ophthalmic device 110 is transmitted from the ophthalmic device 110 and received by the management server 140.

[0028] 5, the processing unit 186 reads out image data of the first fundus image (red fundus image) from the image data of the fundus image received from the ophthalmologic apparatus 110. In step 204, the processing unit 186 reads out image data of the second fundus image (green fundus image) from the image data of the fundus image received from the ophthalmologic apparatus 110.

[0029] Here, information contained in the first fundus image (red fundus image) and the second fundus image (green fundus image) will be described.

[0030] The eye is structured such that the vitreous body is covered by multiple layers with different structures. These multiple layers, from the innermost on the vitreous body side to the outermost, include the retina, choroid, and sclera. R light passes through the retina and reaches the choroid. Therefore, the first fundus image (R-color fundus image) contains information about the blood vessels present in the retina (retinal blood vessels) and the blood vessels present in the choroid (choroidal blood vessels). In contrast, G light only reaches the retina. Therefore, the second fundus image (G-color fundus image) contains only information about the blood vessels present in the retina (retinal blood vessels).

[0031] In step 206, the image processing unit 182 extracts retinal blood vessels from the second fundus image (green fundus image) by applying black hat filtering to the second fundus image (green fundus image). Black hat filtering is filtering that extracts black lines.

[0032] Black hat filtering is a process of taking the difference between the image data of the second fundus image (green fundus image) and the image data obtained by a closing process, which performs N times (N is an integer greater than or equal to 1) of dilation and N times of contraction on this original image data. Retinal blood vessels absorb irradiated light (not only green light, but also red or infrared light), so they appear darker in the fundus image than the surrounding area. Therefore, by applying black hat filtering to the fundus image, the retinal blood vessels can be extracted.

[0033] In step 208, the image processing unit 182 removes the retinal blood vessels extracted in step 206 from the first fundus image (red fundus image) by inpainting processing. Specifically, the retinal blood vessels are made less noticeable in the first fundus image (red fundus image). More specifically, the positions of the retinal blood vessels extracted from the second fundus image (green fundus image) are identified in the first fundus image (red fundus image), and the pixel value of the pixel in the first fundus image (red fundus image) at the identified position is processed so that the difference between the pixel and the average value of the surrounding pixels is within a predetermined range (for example, 0).

[0034] In this way, the retinal blood vessels are made less noticeable in the first fundus image (red fundus image) in which retinal blood vessels and choroidal blood vessels are present, and as a result, the choroidal blood vessels can be made relatively more noticeable in the first fundus image (red fundus image). As a result, a choroidal blood vessel image in which the choroidal blood vessels are made relatively more noticeable can be obtained, as shown in FIG. 6C.

[0035] In step 210, the image processing unit 182 performs CLAHE (Contrast Limited Adaptive Histogram Equalization) processing on the image data of the first fundus image (red fundus image) in which the choroidal blood vessels are relatively prominent, thereby enhancing the choroidal blood vessels in the first fundus image (red fundus image). As a result, a choroidal blood vessel image in which the choroidal blood vessels are enhanced is obtained, as shown in FIG. 6D .

[0036] In step 212, the image processing unit 182 performs choroid analysis processing using image data of the choroidal vessel image in which the choroidal vessels are enhanced, such as vortex vein position detection processing and choroidal vessel orientation analysis processing.

[0037] In step 214, the processing unit 186 stores the choroidal vessel image and choroidal analysis data in the memory 164.

[0038] When the processing of step 214 is completed, the image processing program ends.

[0039] Incidentally, a doctor operating the image viewer 150 may want to know the state of the choroidal blood vessels when diagnosing a patient. In this case, the doctor sends an instruction to the management server 140 via the image viewer 150 to send data on the display screen in the choroidal blood vessel analysis mode.

[0040] The display control unit 184 of the management server 140, which receives an instruction from the image viewer 150, creates data for the display screen in the choroidal blood vessel analysis mode.

[0041] The data on the display screen in the choroidal vessel analysis mode will be described. When a patient's fundus is photographed, the patient's personal information is input to the ophthalmologic device 110. The personal information includes the patient's ID, name, age, and eyesight. When a patient's fundus is photographed, information indicating whether the eye whose fundus is being photographed is the right eye or the left eye is also input. When a patient's fundus is photographed, the date and time of photographing is also input. In addition to image data of the fundus image, the personal information, information on the right eye or the left eye, and data on the date and time of photographing are transmitted from the ophthalmologic device 110 to the management server 140.

[0042] The display control unit 184 reads out from the memory 164 the personal information including the axial length, the photographing date and time, the information on the right eye and the left eye, the first fundus image (red-colored fundus image), the second fundus image (green-colored fundus image), and the choroidal blood vessel image as data for the display screen in the choroidal blood vessel analysis mode, and creates the display screen 300 in the choroidal blood vessel analysis mode shown in FIG. 7.

[0043] The management server 140, which created the display screen 300, transmits data for the display screen 300 in choroidal vessel analysis mode to the image viewer 150. Upon receiving the data for the display screen in choroidal vessel analysis mode, the image viewer 150 displays FIG. 7 on the display 156 of the image viewer 150 based on the data for the display screen in choroidal vessel analysis mode.

[0044] Here, we will explain the display screen 300 of the choroidal vessel analysis mode shown in Fig. 7. As shown in Fig. 7, the display screen 300 of the choroidal vessel analysis mode shown in Fig. 7 has a personal information display field 302 that displays the patient's personal information, an image display field 320, and a choroidal analysis tool display field 330.

[0045] The personal information display field 302 has a patient ID display field 304 , a patient name display field 306 , an age display field 308 , an axial length display field 310 , and a visual acuity display field 312 .

[0046] The image display field 320 has a photographing date display field 322N1, a right eye information display field 324R, a left eye information display field 324L, an RG image display field 326, and a choroidal blood vessel image display field 328. The RG image is an image obtained by combining the first fundus image (R-color fundus image) and the second fundus image (G-color fundus image) at a predetermined ratio (for example, 1:1) of the magnitude of each pixel value.

[0047] The choroid analysis tool display field 330 includes a plurality of choroid analysis tools that instruct the image viewer 150 to perform processing, such as a vortex vein location analysis icon 332, a symmetry icon 334, a vessel diameter icon 336, a vortex vein and macula / optic disc icon 338, and a choroid analysis report icon 340. The vortex vein location analysis icon 332 instructs the user to identify the vortex vein location. The symmetry icon 334 instructs the user to analyze the symmetry of the vortex vein. The vessel diameter icon 336 instructs the user to execute a tool that analyzes the diameter of the choroidal vessels. The vortex vein and macula / optic disc icon 338 instructs the user to analyze the location between the vortex vein, the macula, and the optic disc. The choroid analysis report icon 340 instructs the user to display a choroid analysis report.

[0048] In the example shown in FIG. 7, an RG image and a choroid image are displayed when the fundus of a patient identified by patient ID: 123456 was photographed on January 1, 2016.

[0049] On the other hand, if the patient's fundus is subsequently photographed on, for example, January 1, 2017 and January 1, 2018, and the above data is acquired, RG images and choroid images are displayed for each of the photographing dates, January 1, 2016, January 1, 2017, and January 1, 2018, as shown in FIG. 8. The photographing dates, January 1, 2016, January 1, 2017, and January 1, 2018, are displayed in photographing date display fields 322N1, 322N2, and 322N3, respectively. For example, as shown in FIG. 8, when photographing date display field 322N3 displaying January 1, 2018, is clicked, the RG image and choroid image photographed on January 1, 2018 are displayed.

[0050] As described above, in this embodiment, a choroidal vessel image is generated.

[0051] Conventionally, R images of the fundus taken with a red light source contain both choroidal and retinal blood vessels, and the retinal blood vessels affect the analysis of the choroidal blood vessels.

[0052] In contrast, in this embodiment, retinal blood vessels are removed from the R image by image processing to generate a choroidal blood vessel image in which only choroidal blood vessels are present, thereby reducing the influence of retinal blood vessels on the analysis of choroidal blood vessels.

[0053] Next, various modifications of the technique of the present disclosure will be described. <First Modification> In the above embodiment, after step 212 in Fig. 5, the display control unit 184 executes the process of step 214. The technology of the present disclosure is not limited to this. For example, first, when the process of step 212 is completed, the image processing program is terminated, and the display control unit 184 may execute the process of step 214 when the management server 140 receives an instruction to transmit data of the display screen in choroidal vascular analysis mode.

[0054] <Second Modification> In the above embodiment, an example has been described in which a fundus image is acquired with an internal light irradiation angle, which is the angle from the center of the eyeball, of about 200 degrees using the ophthalmic apparatus 110. The technology of the present disclosure is not limited to this, and the technology of the present disclosure may be applied to a fundus image acquired with a fundus camera, or to fundus images captured with various ophthalmic apparatuses, such as ophthalmic apparatuses or fundus cameras with an internal irradiation angle of 100 degrees or less.

[0055] <Third Modification> In the above embodiment, the management server 140 executes the image processing program. The technology of the present disclosure is not limited to this. For example, the ophthalmic apparatus 110 or the image viewer 150 may execute the image processing program. When the ophthalmic apparatus 110 executes the image processing program, the image processing program is stored in the memory 24, and the choroidal blood vessel image and choroidal analysis data in step 214 are saved in the memory 24. When the image viewer 150 executes the image processing program, the image processing program is stored in the memory of the image viewer 150, and the choroidal blood vessel image and choroidal analysis data in step 214 are saved in the memory of the image viewer 150.

[0056] <Fourth Modification> In the above embodiment, the ophthalmic system 100 including the ophthalmic apparatus 110, the axial length measurement apparatus 120, the management server 140, and the image viewer 150 has been described as an example. However, the technology of the present disclosure is not limited thereto. For example, as a first example, the axial length measurement apparatus 120 may be omitted, and the ophthalmic apparatus 110 may further have the functions of the axial length measurement apparatus 120. Furthermore, as a second example, the ophthalmic apparatus 110 may further have the functions of at least one of the management server 140 and the image viewer 150. For example, if the ophthalmic apparatus 110 has the functions of the management server 140, the management server 140 can be omitted. In this case, the image processing program is executed by the ophthalmic apparatus 110 or the image viewer 150. Furthermore, if the ophthalmic apparatus 110 has the functions of the image viewer 150, the image viewer 150 can be omitted. As a third example, the management server 140 may be omitted, and the image viewer 150 may perform the functions of the management server 140.

[0057] <Fifth Modification> In the above embodiment, a red-colored fundus image captured with red light is used as the first fundus image, but an IR fundus image captured with infrared light may also be used. That is, since red light with a wavelength of 630 nm to 780 nm or infrared light with a wavelength of 780 nm or more is used, the light reaches not only the retina but also the choroid. In particular, IR light can capture images of deep regions of the choroid. That is, since light capable of capturing images of the choroidal region on the sclera side of the eyeball is used, light reaches the choroid, which is one of multiple layers covering the vitreous body of the eyeball and including the retina and choroid, which have different structures located from the innermost to the outermost on the vitreous body side, and the region to which the light reaches can be captured.

[0058] <Sixth Modification> In the above embodiment, the fundus image is obtained by simultaneously photographing the fundus of the subject's eye 12 using G light and R light. The technology of the present disclosure is not limited to this. For example, the fundus of the subject's eye 12 may be photographed using G light and R light at different times. In this case, step 208 is performed after aligning the first fundus image (R-color fundus image) and the second fundus image (G-color fundus image).

[0059] <Seventh Modification> In the above embodiment, a choroidal blood vessel image is generated based on the first fundus image (red fundus image) and the second fundus image (green fundus image), but the technology of the present disclosure is not limited to this, and a choroidal blood vessel image may be generated based on the fundus image (red fundus image). Image processing for generating a choroidal blood vessel image based on the fundus image (red fundus image) is shown in Figure 9.

[0060] In the above embodiment, the fundus of the subject eye 12 is photographed simultaneously using G light and R light, but in the seventh variant, the fundus of the subject eye 12 is photographed using only R light to obtain a fundus image (R-color fundus image).

[0061] The image processing program in Fig. 9 also starts when image data of a fundus image (red fundus image) is transmitted from the ophthalmologic apparatus 110 and received by the management server 140. Note that the image processing in Fig. 9 includes processes similar to those in Fig. 5, and therefore the same processes are denoted by the same reference numerals and detailed descriptions thereof will be omitted.

[0062] As shown in FIG. 9, after the processing of step 202, in step 205, the image processing unit 182 extracts retinal blood vessels from the fundus image (red fundus image) by applying black hat filter processing to the fundus image (red fundus image). As described above, a fundus image (red fundus image) contains information about blood vessels in the retina (retinal blood vessels) and blood vessels in the choroid (choroidal blood vessels). However, when black hat filtering is performed on a fundus image (red fundus image), only information about the retinal blood vessels is extracted. Retinal blood vessels absorb not only green light but also red light, so they appear darker than the surrounding area in the fundus image. Therefore, by performing black hat filtering on a fundus image, the retinal blood vessels can be extracted. After step 205, steps 208 to 214 are executed.

[0063] As described above, in the seventh variant, the fundus of the test eye 12 is photographed using only R light to obtain a fundus image (R-color fundus image), and a choroidal blood vessel image can be generated from the fundus image (R-color fundus image). Note that, unlike the fifth modified example, the image is not limited to being captured using R light, and an IR fundus image captured using IR light may also be used.

[0064] <Other variations> The data processing described in the above embodiment is merely an example, and it goes without saying that unnecessary steps may be deleted, new steps may be added, or the processing order may be changed, without departing from the spirit of the invention. Furthermore, in the above embodiment, an example was given in which data processing is realized by a software configuration using a computer, but the technology of the present disclosure is not limited to this. For example, instead of a software configuration using a computer, data processing may be performed only by a hardware configuration such as an FPGA or an ASIC. Part of the data processing may be performed by a software configuration, and the remaining part may be performed by a hardware configuration.

[0065] This application claims priority from Japanese Patent Application No. 2018-052246, filed March 20, 2018, the entire contents of which are incorporated herein by reference. In addition, all publications, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual publication, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. an acquisition unit for acquiring a fundus image including retinal blood vessels and choroidal blood vessels; an image processing unit that extracts the retinal blood vessels from the fundus image and adjusts pixel values ​​at the positions of the retinal blood vessels so as to reduce a difference between pixel values ​​at the positions of the retinal blood vessels in the fundus image and an average pixel value around the positions of the retinal blood vessels, thereby generating a choroidal blood vessel image; Image processing device.

2. The image processing device according to claim 1 , wherein the image processing unit performs processing to enhance choroidal blood vessels in the choroidal blood vessel image.

3. The image processing device according to claim 1 or 2, wherein the image processing unit detects at least one of a vortex vein position and an orientation of the choroidal vessels from the choroidal vessel image.

4. The image processing device according to any one of claims 1 to 3, wherein the acquisition unit acquires a fundus image including retinal blood vessels and choroidal blood vessels obtained by photographing the fundus with light that passes through a retinal layer and reaches a choroidal layer.

5. 5. The image processing device according to claim 1, wherein the image processing unit outputs image data of at least one of the fundus image and the choroidal blood vessel image.

6. The image processing device according to any one of claims 1 to 5, wherein the image processing unit displays at least one of personal information, shooting date and time, information on the right eye and left eye, the fundus image, and the choroidal blood vessel image.

7. Acquiring a fundus image including retinal and choroidal vessels; extracting the retinal blood vessels from the fundus image; An image processing method for generating a choroidal blood vessel image by adjusting pixel values ​​at the position of the retinal blood vessel in the fundus image so as to reduce a difference between the pixel values ​​at the position of the retinal blood vessel and an average pixel value around the position of the retinal blood vessel.

8. The image processing method according to claim 7 , wherein generating the choroidal vessel image includes performing a process of enhancing choroidal vessels in the choroidal vessel image.

9. 9. The image processing method according to claim 7, further comprising at least one of detecting a position of a vortex vein from the choroidal vessel image and analyzing an orientation of the choroidal vessels.

10. 10. The image processing method according to claim 7, wherein the acquiring step includes acquiring a fundus image including retinal blood vessels and choroidal blood vessels, the fundus image being obtained by photographing the fundus with light that passes through a retinal layer and reaches a choroidal layer.

11. The image processing method according to any one of claims 7 to 10, wherein generating the choroidal vessel image includes outputting image data of at least one of the fundus image and the choroidal vessel image.

12. The image processing method according to any one of claims 7 to 11, further comprising displaying at least one of personal information, a photographing date and time, information on the right eye and the left eye, the fundus image, and the choroidal blood vessel image.

13. A program for causing a computer to execute the image processing method according to any one of claims 7 to 12.

14. an imaging unit that photographs the fundus with light that passes through the retinal layer and reaches the choroidal layer, and acquires a fundus image including retinal blood vessels and choroidal blood vessels; an image processing unit that extracts the retinal blood vessels from the fundus image and adjusts pixel values ​​at the positions of the retinal blood vessels so as to reduce a difference between pixel values ​​at the positions of the retinal blood vessels in the fundus image and an average pixel value around the positions of the retinal blood vessels, thereby generating a choroidal blood vessel image; Ophthalmology equipment.

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