JP2005261533A - Ophthalmologic image processor and processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ophthalmologic image processor and processing method capable of appropriately removing flares included in images. <P>SOLUTION: A fundus oculi image Er' is inputted from photographing equipment in S101. A boundary area F2 is set first in order to decide a maximum area F1 in S102, and the diameter of the boundary area F2 is reduced and a circular area F1a is set so as to remove the rough flares of a photographed image in S103. In S104, in order to remove eccentric flares, the circle of the same diameter as the one of the area F1a is made eccentric and an area F1b is set. The area of the flare remaining inside the common area of sets F1a and F1b is set as F1c in S105, and (the common part of the sets F1a and F1b)-F1c is set as a diagnosable maximum area F1 in S106. In S107, the outer side of the area F1 is set as a transmission area, a compositing processing with a background image is performed and recording is performed as one inspection image, or an overlaying processing with the background image is performed in S108. A composited image is displayed on a monitor in S109, the displayed image is confirmed in S110, advancing to S111 is performed and diagnostic reading is ended. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ophthalmic image processing apparatus and processing method used for fundus examination and the like in ophthalmic clinics, group medical examinations, medical checkups, and the like.

  Conventionally, in a fundus camera, a mask is placed in front of a recording means such as a film as a light-shielding member that blocks the light toward the peripheral area in order to clarify the effective shooting range by removing flare generated around the fundus image. Alternatively, a mask is placed on the imaging plane, and an optical system that re-images the mask and the fundus image is placed for shooting.

  In addition, a technique is also known in which an unnecessary area in an ophthalmologic image photographed electronically as shown in Patent Document 1 is electrically masked so that an optical member is unnecessary.

JP-A-9-2016278

  However, in the ophthalmologic photographing apparatus having the light-shielding member as described above, a physical mask must be disposed in the optical system, so that the mask image is reflected at a predetermined position regardless of the flare state. There is a problem that a part that cannot be interpreted by a flare is seen, or a part where an image that can withstand interpretation is originally captured is hidden by a mask.

  The masks used in these ophthalmologic photographing apparatuses are arranged in the position and size where flare will not be reflected in the optical design or empirically according to the optical center. Flares often occur inside the mask. If the position where the flare occurs and the position of the optically fixed mask do not match due to shooting conditions, image sensor position displacement, etc., it will occur only in one direction where the flare is in the form of overlapping circles Resulting in.

  In addition, depending on the diopter of the subject, individual differences in the imaging device, adjustment differences, etc., the flare diameter will be smaller than the mask design value, and flare will occur around the entire mask inside where the flare should not enter. There is also a problem that gets in.

  In addition, when the shooting mode is changed, the zooming function, the small pupil diameter shooting function, etc., the flare generation position and size change, so that there is a problem that the flare enters the preset mask. .

  An object of the present invention is to provide an ophthalmic image processing apparatus and a processing method that can solve the above-described problems and can appropriately remove flare contained in an image.

  To achieve the above object, an ophthalmic image processing apparatus according to the present invention includes a flare detection unit that detects flare of an image obtained by photographing an eye to be examined, and mask area information according to flare information detected by the flare detection unit. A mask area determining means for determining, and an image processing output means for processing the image based on the mask area information determined by the mask area determining means.

  Further, an ophthalmic image processing method according to the present invention includes a flare detection step for detecting a flare of an image obtained by photographing an eye to be examined, and a mask region determination for determining mask region information according to flare information detected by the flare detection step. And an image processing output process for processing the image based on the mask area information determined by the mask area determination process.

  According to the ophthalmologic image processing apparatus and the processing method of the present invention, flare enters the inside of the mask regardless of the state of the eye or apparatus by appropriately detecting and removing only the flare included in the captured image. Image information effective for diagnosis included in the photographed image can be utilized to the maximum.

  Furthermore, since the probability of finding a lesion site that has been hidden outside the mask in the past increases, it is also effective for early detection of a disease.

The present invention will be described in detail based on the illustrated embodiments.
FIG. 1 is a block diagram of an ophthalmic image processing apparatus. On an optical path from an observation alignment light source 1 to an objective lens 2, a condenser lens 3, a still image photographing light source 4 such as a strobe, a condenser lens 5, and a mirror 6 are shown. , A lens 7, a diaphragm 8 having a ring-shaped opening, a relay lens 9, and a perforated mirror 10 having an opening in the center. On the optical path behind the perforated mirror 10, a focus lens 11, a photographing lens 12 having a zooming function, a switching mirror 13, and a high-definition imaging camera 14 are sequentially arranged. A high sensitivity camera 15 for observation is arranged. The focus lens 11 and the photographing lens 12 are moved in the optical axis direction by operating the focus knob 16.

  Outputs of the imaging camera 14 and the high-sensitivity camera 15 are both connected to an image processing display unit 17, and the image processing display unit 17 is connected to a monitor 18 for displaying a fundus image and an area change instruction unit 19. Accordingly, the display range of the monitor 18 can be changed.

  In such a configuration, the light beam emitted from the observation alignment light source 1 passes through the condenser lens 3, the still image photographing light source 4, and the condenser lens 5, and is reflected upward by the mirror 6. It passes through the opening and the relay lens 9, is reflected leftward by the perforated mirror 10, passes through the objective lens 2, and illuminates the fundus Er through the pupil Ep of the eye E to be examined.

  The fundus image Er ′ illuminated by the illumination light passes through the pupil Ep, the objective lens 2, the focus lens 11, and the photographing lens 12, is reflected downward by the switching mirror 13, and forms an image on the photographing image plane of the high-sensitivity camera 15. . The obtained fundus oculi image Er ′ is converted into an electrical signal and input to the image processing display means 17. The image processing display means 17 includes flare detection means, mask area determination means, and mask composition means, and the fundus oculi image Er 'generated through these processing steps is displayed on the monitor 18.

  The photographer checks the fundus image Er ′ on the monitor 18 and confirms the photographing region, alignment, and focus state. If the focus is out of focus, the focus knob 11 is operated so that the focus lens 11 is turned on. Move in the axial direction to focus.

  When the examiner presses the photographing switch after the focusing is completed, the switching mirror 13 is retracted out of the optical path and jumps up to the position indicated by the broken line, and the still image photographing light source 4 emits light. The light beam from the still image photographing light source 4 reaches the condenser lens 5 and then illuminates the fundus Er through the same optical path as the light beam emitted from the observation alignment light source 1.

  In this case, the fundus oculi image Er ′ passes through the pupil Ep, passes through the objective lens 2, the hole of the perforated mirror 10, the focus lens 11, and the photographic lens 12, and forms an image on the photographic image plane of the imaging camera 14. The fundus oculi image Er ′ is converted into an electrical signal by the imaging camera 14 and then stored in an image memory in the image processing display means 17. After performing flare detection, mask area setting, and mask composition, the image is displayed on the monitor 18 as a still image. Is displayed.

  FIG. 2 is an explanatory diagram of the fundus oculi image Er ′ displayed on the monitor 18. The actual monitor 18 displays patient information, operation buttons for operating the image display application, and the like, but only the display of the fundus will be described here. A peripheral portion where no image is displayed is a mask portion M.

  FIG. 3 shows the positional relationship between the fundus image Er ′ captured by the imaging camera 14 and the sensor unit of the imaging camera 14. The optical axis of the imaging optical system and the center of the imaging camera 14 are arranged so as to be substantially concentric, and the fundus oculi image Er ′ is formed at the approximate center of the imaging camera 14.

  In this case, the fundus oculi image Er 'can be divided into regions F0 to F3. F0 with a central diameter R0 is a circular area that is effective for diagnosis without flare, F1 around it is an area of an arbitrary shape that is extracted only with a portion that is effective for diagnosis without flare, and F2 with a diameter R2 around it is The boundary region where the flare is unclear and the optical fundus image Er ′ is not captured due to optical design, and F3 outside thereof is an ineffective region having an unclear portion on the outer periphery.

  As shown in FIG. 3A, the area F2 where the flare enters usually occurs concentrically around the sensor portion of the imaging camera 14, but the center of the circle is slightly shifted as shown in FIG. In some cases, flare occurs in a decentered form, or as shown in (c), the flare is not circular but occurs only in a specific region.

  In a normal ophthalmologic photographing apparatus, a region F0 in which no flare enters is predetermined as a diameter R0 from the center of the sensor by optical design. Usually, only this region F0 is displayed or printed and used for diagnosis or patient explanation. . Here, if there is a flare in the peripheral part, it is not only possible to determine whether or not the image has been taken normally, but also the range for image diagnosis becomes indefinite and the diagnosis efficiency decreases, so that the region F0 can be absorbed so that individual differences can be absorbed. Is set slightly inside, and usually only clear areas are displayed.

  However, depending on the eye to be examined and its imaging conditions, an image that can withstand diagnosis may be captured outside the region F0, or a flare that may not withstand diagnosis may enter inside the region F0. Therefore, in the ophthalmic image processing apparatus according to the present embodiment, the maximum area F1 of the photographed image that can withstand diagnosis is displayed as the eye image to be examined, and the remaining peripheral portion is displayed as the mask portion M.

  In order to set the region F1, first, the boundary region F2 where the fundus image Er 'is not captured at all and the diameter R2 are determined. It is important to set the radius R2 that determines the boundary of the region F2. In this area, an image other than the fundus oculi Er, that is, the inside of the fundus camera is captured, and there is a possibility of causing a misdiagnosis, so that it should not be output to a diagnostic monitor or printing. Note that the boundary region F2 having the diameter R2 can be made variable in accordance with changes in the optical system of the ophthalmologic photographing apparatus such as a small pupil diameter photographing switch, a zooming switch, and a photographing mode.

  Next, in order to determine the maximum region F1 of the fundus oculi image Er 'that can withstand the diagnosis, in FIG. 4A, first, a region F1a having the same position and size as the boundary region F2 is set. The initial value of the diameter R1a is R2, the spatial frequency of the circumferential inner edge of the circular region F1a is lower than a predetermined level, and a portion where the luminance value is equal to or higher than the predetermined level is determined to be flare, and the flare is eliminated. The area F1a having the diameter R1a is reduced while the center is fixed. The spatial frequency and luminance value thresholds determined as flare are not limited to those specified in advance, and any value may be specified. Further, as a parameter for determining flare, a color signal of the fundus oculi image Er ′ or an optical characteristic value of the photographing apparatus may be used.

  At this time, the region F1a does not need to be reduced to a size where the flare is completely eliminated in the circle, and at the stage where the portion judged to be flare falls below a certain ratio in the circumferential inner edge of the region F1a, Is determined as a region F1a having a final diameter R1a.

  Next, in FIG. 4B, a region F1b having the same position and size as the circular region F1a is set, the center of the region F1b is shifted in the horizontal and vertical directions, and at the boundary portion of the region indicated by F1a∩F1b. The center is fixed when the portion judged to be flare falls below a certain ratio, and the region indicated by the diameter R1b at that time is determined as F1b.

  Further, in FIG. 4C, when an area determined to be flare remains at the boundary portion of the area indicated by F1a１F1b, the area is set as the exception area F1c. Finally, as shown in FIG. 4C, the maximum area not including the flare represented by (F1a∩F1b) −F1c is determined as F1.

  In the process of displaying the fundus oculi image Er 'on the monitor 18, when an image to be displayed is selected, the outside of the region indicated by the maximum region F1 that can be diagnosed is set as a transmissive region. As described above, when the image with the transparent area set is displayed so as to overlap the black background image, only the central portion of the image of the maximum area that can be diagnosed is visible and the surrounding area is displayed on the monitor 18 as the background image.

  Alternatively, an alpha channel may be provided in the image to be displayed, and the image may be partially combined with the background color without being completely transmitted, or a background image other than black may be used. The synthesized image may be recorded as a file, or the area information F1, the background image, and the photographed image before processing can be recorded separately.

  When changing the display range, the area F1 to be displayed may be changed by the operation of the area change instruction means 19. However, since the boundary region F2 in which the fundus image Er 'is not captured is set as the upper limit value, it is not displayed up to the inside of the fundus camera.

  FIG. 5 is a flowchart of processing when masking a photographed image. In step S101, an electronic fundus image Er 'into which no mask image has been optically transferred from the photographing apparatus is input. In step S102, the boundary area F2 in the optical design is set from the image capturing information of the image, and in order to remove rough flare of the captured image in step S103, the diameter of the boundary area F2 is reduced and the circular area F1a is set. .

  In step S104, in order to remove the eccentric flare, a circle having the same diameter as the region F1a is decentered to set the region F1b. In step S105, the flare area remaining in the common area indicated by F1a１F1b is set as F1c, and in step S106, (F1a１F1b) −F1c is set as the maximum diagnosable area F1 for image display. It memorize | stores as a parameter and transfers to the following step S107 or S108.

  In step S107, the outside of the area F1 is set as a transmissive area, combined with the background image, and recorded as one inspection image. In step S108, overlay processing is performed on the background image, but the photographed image and the background image are recorded separately, and the image synthesized in step S109 is displayed on the monitor 18.

  In step S110, the image interpreter checks the image displayed on the monitor 18, and changes the area F1 using the area change instruction means 19 if necessary. If the area F1 has been changed, the process returns to step S108, and image composition and display are performed again. Finally, when the image interpreter confirms the image and completes the diagnosis, the process proceeds to step S111 to end the image interpretation, or the process returns to step S102 to select the next photographed image.

It is a block diagram of an ophthalmic image processing apparatus. It is explanatory drawing of the fundus image formed in an imaging camera. It is explanatory drawing of the flare with respect to a fundus image. It is explanatory drawing of the area | region setting process for removing a flare. It is a flowchart figure of an image interpretation process.

Explanation of symbols

2 Objective Lens 4 Light Source for Still Image Shooting 10 Perforated Mirror 11 Focus Lens 13 Switching Mirror 14 Imaging Camera 17 Image Processing Display Unit 18 Monitor 19 Area Change Instruction Unit

Claims (5)

  Flare detection means for detecting flare of an image obtained by photographing the eye to be examined, mask area determination means for determining mask area information according to flare information detected by the flare detection means, and the mask determined by the mask area determination means An ophthalmic image processing apparatus comprising: image processing output means for processing the image based on region information.   The said mask area | region determination means has a boundary setting means to set the boundary of the flare area | region detected by the said flare detection means, and the site | part which can be diagnosed as boundary information, It is characterized by the above-mentioned. Ophthalmic image processing device.   The ophthalmic image processing apparatus according to claim 1, wherein the image processing output unit includes an image synthesis unit that superimposes and combines the mask region information determined by the mask region determination unit and the image. .   The ophthalmic image processing apparatus according to claim 1, wherein the image processing output unit makes the mask region information determined by the mask region determining unit invisible and visualizes other parts that can be diagnosed.   A flare detection step for detecting flare in an image obtained by photographing the eye to be examined, a mask region determination step for determining mask region information according to flare information detected by the flare detection step, and the mask determined by the mask region determination step An ophthalmic image processing method comprising: an image processing output step for processing the image based on region information.

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