JP2011097992A - Fundus observation apparatus, fundus observation method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of difficulty in adjusting image quality of a fundus image during observation due to a blur in the image quality of the displayed fundus image when displaying the fundus image taken on a real-time basis, and to provide the fundus image having high image quality on a real-time basis by carrying out image processing to the fundus image during photographing. <P>SOLUTION: A fundus observation apparatus captures the fundus image and a tomographic image. The fundus observation apparatus includes an image quality adjusting part (12) for adjusting the image quality of the image during photography on the basis of the fundus image taken before photographing the tomographic image, and a display part (13) for displaying the image after the image adjustment. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to image quality adjustment of a fundus image at the time of tomographic imaging used for ophthalmic medical care and the like.

  An optical coherence tomography (hereinafter referred to as OCT) capable of capturing a tomographic image of the retina usually includes both a mechanism for observing a two-dimensional image of the fundus and a mechanism for acquiring a tomographic image. ing. In such an apparatus, the optical axes of the OCT and fundus image light beams are aligned, and a tomographic image of a site aimed at the fundus image can be acquired. Patent Document 1 discloses a technique for identifying a region of interest while observing a fundus image in real time and capturing a desired tomographic image. Patent Document 2 discloses a technique for improving the image quality of a tomographic image by increasing the intensity of signal light deteriorated by a blood vessel or a lesion of the retina.

JP2008-289579 JP2009-042197

  However, in the conventional fundus oculi observation device, when displaying a fundus image captured in real time, the display quality of the fundus image may be blurred.

A fundus oculi observation device according to an aspect of the present invention for solving the above problems is a fundus oculi observation device that captures a fundus image and a tomographic image,
Image quality adjusting means for adjusting the image quality of the image being captured based on the fundus image captured before capturing the tomographic image;
Display means for displaying an image after adjusting the image quality.

  According to the present invention, the image quality of an image for observation can be adjusted in real time.

The figure which shows the function structure of the fundus observation apparatus 1 which concerns on an Example. Schematic diagram of the optical system of the fundus oculi observation device 7 is a flowchart illustrating a processing procedure of the fundus oculi observation device 1 according to the first embodiment. Schematic diagram of a fundus image according to the second embodiment 7 is a flowchart illustrating a processing procedure of the fundus oculi observation device 1 according to the second embodiment.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. However, the following description is an example of a suitable fundus apparatus according to the present invention, and the present invention is not limited to this.

  In the present invention, the image processing parameters of the fundus image B being photographed are obtained from the fundus image A stored in advance. Thus, by performing image processing on the fundus image B being shot, it is possible to provide a high-quality real-time fundus image.

  FIG. 1 shows an example of a functional configuration of the fundus oculi observation device 1. The fundus oculi observation device 1 in FIG. 1 includes an image capturing unit 10, an image storage unit 11, an image quality adjustment unit 12, and an adjusted image display unit 13.

  In such a configuration, the image capturing unit 10 captures a desired fundus image in response to a user operation (not shown). FIG. 2 shows a schematic diagram of the image capturing unit 10 and an OCT optical system connected thereto. OCT is a device that captures a tomographic image of the eye, and for example, time domain OCT or Fourier domain OCT is used. A generally used OCT light source has a center wavelength of 840 nm and a wavelength width of ± 25 nm. The fundus image photographing light source used in the image photographing unit 10 has a center wavelength of 940 nm and a wavelength width of ± 100 nm. The light emitted from the fundus image photographing light source is reflected by the perforated mirror and travels toward the eye to be examined. Thereafter, the light reflected from the fundus of the subject's eye passes through the perforated mirror, is reflected by the dichroic mirror, and is received by the camera. In order to reduce noise caused by the OCT light beam in the received light, a filter that can block light having an arbitrary frequency may be placed in front of the camera. Finally, it is possible to acquire a fundus image by processing the received optical signal. The image storage unit 11 acquires and stores the fundus image at least once from the image capturing unit 10 until the tomographic image capturing is started. The image quality adjustment unit 12 adjusts the image quality of the fundus image being shot based on the image quality stored in the image storage unit 11. The adjusted image display unit 13 displays the image adjusted by the image quality adjusting unit 12.

  Next, the processing procedure of the fundus oculi observation device 1 in the present embodiment will be described using the flowchart of FIG.

<Step S301>
In step S <b> 301, the image capturing unit 10 first captures a fundus image of the subject eye before capturing a tomographic image, and transmits the captured image to the image storage unit 11 and the image quality adjustment unit 12.

<Step S302>
In step S <b> 302, the image storage unit 11 receives and stores the fundus image transmitted from the image capturing unit 10. The stored image may be updated at regular time intervals, for example.

<Step S303>
In step S <b> 303, when the user requests to start tomographic imaging, the image storage unit 11 transmits the fundus image stored in the image quality adjustment unit 12 before starting tomographic imaging. If the request has not been issued, the image capturing unit 10 continues to transmit the fundus image to the image storage unit 11 in S301. In step S302, the image storage unit 11 evaluates the image quality of the received image. If the image quality is better than the stored image quality, the image storage unit 11 updates the stored image with the newly received image.

<Step S304>
In step S <b> 304, the image quality adjustment unit 12 obtains image processing parameters based on the stored image received from the image storage unit 11. The image quality of the image being photographed is adjusted according to this parameter.

When image contrast is used for image quality adjustment, the minimum and maximum brightness values of the stored image are obtained, and the brightness of the captured image is the same so that the minimum and maximum brightness values of the captured image are the same. Transform the value linearly. As a result, even if the image being shot has a different contrast, it can be adjusted to the contrast of the image before shooting. Further, in order to obtain the minimum value and the maximum value from the fundus image, for example, the knowledge that the region having a low luminance value is mainly a macular portion and the region having a high luminance value is mainly a nerve papillae may be used. By utilizing this, it is possible to adjust to an image having a contrast in which the macular portion is low and the optic nerve head is expressed with a high luminance value. The macular part and the optic nerve head use a setting method based on existing image processing such as manual setting by a user or threshold processing of an image.
The image adjusted by these methods is transmitted to the adjusted image display unit 13.

<Step S305>
In step S305, the adjusted image display unit 13 receives and displays the image adjusted by the image quality adjusting unit 12.

  According to the configuration described above, by storing the fundus image before capturing the tomographic image, the image quality of the fundus image during the tomographic image capturing can be matched with the image quality of the fundus image before capturing. Therefore, the user can accurately capture a tomographic image of a portion to be noted while observing an image before the image quality is deteriorated.

  In the first embodiment, the example in which the image quality of the fundus image being captured is adjusted based on the fundus image stored before the tomographic image is captured is shown. However, the first embodiment does not consider eye fixation fine movement or head movement, and therefore there is a risk that the image quality may be adjusted while the positions of the stored image of the fundus image and the image being captured are shifted. In addition, since the image quality is adjusted for the entire image, the image quality is similarly adjusted for regions similar to the pixel values of the stored image. Therefore, in the present embodiment, an example is shown in which the stored image and the captured image are aligned, and then the image quality of the captured fundus image is adjusted.

More specifically, the image quality adjustment unit 12 first obtains a positional shift between the stored image and the image being captured by a known method such as template matching, and aligns the two images. Next, as shown in FIG. 4, each of the fundus image to the width N _x position is _matched, a plurality of rectangular regions having a pixel height N _y, any number of pixels n _x, so as to overlap only n _y Set. Further, a minimum value and a maximum value are obtained in each rectangular area in the fundus image being captured and the stored image. Finally, the minimum and maximum values in each rectangular area of the fundus image being captured are set to the pixel values of each rectangular area of the captured image so that they match the minimum and maximum values of the rectangular area at the same position in the stored image. Perform linear transformation.

  Next, a processing procedure of the fundus oculi observation device 1 in the present embodiment will be described using the flowchart of FIG. Since S501, S502, S503, and S506 are the same as those in the first embodiment, description thereof is omitted.

<Step S504>
In step S <b> 504, the image adjustment unit 12 obtains a positional deviation between the stored image received from the image storage unit 11 and the in-capture fundus image received from the image capturing unit.

<Step S505>
In step S505, the image adjustment unit 12 adjusts the image quality of the currently-captured image by the method described above. The adjusted fundus image is transmitted to the adjusted image display unit 13.

  According to the configuration described above, by aligning the fundus image stored before capturing the tomographic image and the fundus image being captured, the image is being captured without being affected by the fixation movement or the movement of the head. The image quality of the fundus image can be matched with the image quality of the fundus image before photographing.

(Other examples)
In the first embodiment, an example is shown in which the entire image is subjected to image quality adjustment, and in the second embodiment, the inside of each rectangular area is subjected to image quality adjustment. However, the region imaged by OCT is only the target region of the fundus image. Therefore, it is conceivable to adjust the image quality only in the targeted area. In such a case, first, the image quality adjustment unit 12 acquires the size of the imaging region from the OCT. Next, the image quality of the rectangular area in the fundus image surrounded by the size of the OCT imaging area is adjusted by the method described above. As described above, by adjusting the image quality only in the area necessary for imaging the OCT, it is possible to increase the processing speed and adjust the image quality without being affected by noise mixed in other areas.

  Each of the above embodiments implements the present invention as an information processing apparatus. However, the embodiment of the present invention is not limited to the information processing apparatus. The present invention can also be realized as software that runs on a computer. The CPU of the information processing apparatus controls the entire computer using computer programs and data stored in RAM and ROM. In addition, the execution of software corresponding to each unit of the information processing apparatus is controlled to realize the function of each unit.

DESCRIPTION OF SYMBOLS 1 Fundus observation apparatus 10 Image photographing unit 11 Image storage unit 12 Image quality adjusting unit 13 Adjusted image display unit

Claims (4)

A fundus oculi observation device that captures fundus images and tomographic images,
Image quality adjusting means for adjusting the image quality of the image being captured based on the fundus image captured before capturing the tomographic image;
Display means for displaying the image after adjusting the image quality;
A fundus oculi observation device comprising:   The fundus oculi observation device according to claim 1, wherein the image quality adjustment unit further includes an alignment unit that aligns the position of the stored image and the image being captured. An image processing method of a fundus oculi observation device that captures a tomographic image while capturing a fundus image,
An image quality adjustment step for adjusting the image quality of the image being captured based on the image quality of the fundus image captured before capturing the tomographic image;
A display step of displaying an image after adjusting the image quality,
An image processing method comprising:   A computer program for causing a computer to execute the image processing method according to claim 3.

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