JP2017221741A - Image formation device, image formation method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for generating a two-dimensional image without any quality degradation, and to provide a method and program.SOLUTION: An image formation device includes: reconfiguration means for reconfiguring a tomogram image in a prescribed range of a measuring object based on interference light generated by causing return light of measuring light returned from the measuring object to interfere with reference light; and generation means for generating a two-dimensional image with a pixel value selected based on descending order of pixel values for each pixel value row in a depth direction of the tomographic image.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a technique for obtaining a two-dimensional image from information of a tomographic image obtained by optical interference.

  Currently, an imaging device based on optical coherence tomography (OCT) using multiwavelength lightwave interference is applied to the human body in order to obtain, for example, internal information in an endoscope or retina information in an ophthalmic device. Is expanding. An imaging device applied to the eye is becoming an indispensable device in a specialized retina outpatient as an ophthalmic device.

  Such an imaging apparatus is an apparatus that can irradiate a sample with measurement light, which is low-coherent light, and measure backscattered light from the sample by using an interference system. And when applied to the eye, it is possible to capture a tomographic image of the eye to be examined with high resolution by scanning the measurement light on the eye to be examined. Yes.

  In addition, as disclosed in Patent Document 1, in order to confirm the imaging range of a tomographic image, a surface image of an imaging target such as a fundus surface can be acquired.

  On the other hand, there is a demand for more accurately confirming which position on the fundus surface to be imaged is the tomographic position.

  Therefore, a technique for generating a two-dimensional image in which the fundus is viewed from the front in a pseudo manner from a plurality of tomographic images (hereinafter referred to as “two-dimensional image”) is known. In this technique, pixel values in a predetermined range in the depth direction obtained by one A scan are integrated. Then, by obtaining these accumulated values for all A scans, it is possible to generate a two-dimensional image of the retina using only tomographic images.

JP 2011-36431 A

  However, in the above-described technique, a two-dimensional image is generated by integrating the pixel values in a predetermined range obtained by the A scan in the depth direction of the retina, so that noise components included in the information in the depth direction are unnecessary. Information is also accumulated. For this reason, effective information of the intensity image is relatively decreased, and the quality of the intensity image may be deteriorated.

  In view of the above problems, an object of the present invention is to generate a two-dimensional image without deteriorating the quality.

In order to achieve the above object, the present image generation apparatus includes:
An acquisition means for acquiring a three-dimensional tomographic image of a predetermined range of the fundus based on interference light obtained by irradiating the fundus with measurement light and causing interference between return light from the fundus and reference light;
Selection means for selecting pixel values at predetermined positions from the top when arranged in the order of pixel value size for each pixel value sequence in the depth direction of each tomographic image included in the three-dimensional tomographic image;
Generating means for generating a two-dimensional image different from the tomographic image with the pixel value selected by the selecting means;
With
When the layer indicating the range in the depth direction for generating the two-dimensional image is selected, and when the layer indicating the range in the depth direction for generating the two-dimensional image is not selected It differs from the said predetermined order in.

  According to the present invention, a two-dimensional image can be generated without degrading.

It is a block diagram of an imaging system. It is a side view of an imaging system. 1 is a diagram illustrating a configuration of an image processing apparatus according to Embodiment 1. FIG. It is a block diagram of the optical system of an imaging device. 3 is a flowchart illustrating a processing flow of the image processing apparatus according to the first embodiment. It is a figure which shows the pixel value sequence of A scan image. It is a figure which shows rearrangement of a pixel value. It is a figure which shows the two-dimensional image of a retina. It is a figure which shows the example of a display of a tomogram and a two-dimensional image. 6 is a diagram illustrating a configuration of an image processing apparatus according to Embodiment 2. FIG. 10 is a flowchart illustrating a processing flow of the image processing apparatus according to the second embodiment.

[Embodiment 1]
FIG. 1 is a diagram illustrating a configuration example of a photographing system 1000 including an image processing device 100 according to the first embodiment and a photographing device 1 connected thereto. The image processing apparatus 100 includes a central processing unit (CPU) 10, a main memory 11, a magnetic disk 12, and a display memory 13. The photographing system 1000 includes a monitor 928, a mouse 929-1, and a keyboard 929-2.

  The CPU 10 mainly controls the operation of each component of the image processing apparatus 100. The main memory 11 stores a control program executed by the CPU 10 and provides a work area when the CPU 10 executes the program. The magnetic disk 12 stores an operating system (OS), peripheral device drivers, various application software including a program for performing deformation estimation processing, which will be described later, and the like. The display memory 13 temporarily stores display data for the monitor 928. The monitor 928 is, for example, a CRT monitor or a liquid crystal monitor, and displays an image based on data from the display memory 13. The mouse 929-1 and the keyboard 929-2 perform pointing input and character input by the user, respectively. The above components are connected to each other via a common bus 17 so that they can communicate with each other.

  The image processing apparatus 100 is connected to the photographing apparatus 1 via a local area network (LAN) and can acquire image data from the photographing apparatus 1. Note that the form of the present invention is not limited to this, and the connection with these devices may be performed via another interface such as USB or IEEE1394. Moreover, the structure which reads required data via LAN etc. from the external devices 3, such as a data server which manages these data, may be sufficient. Further, a storage device such as an FDD, a CD-RW drive, an MO drive, a ZIP drive or the like may be connected to the image processing apparatus 100, and necessary data may be read from these drives.

  In FIG. 2, 324, 323, 951, 950, and 900 represent the configurations of the photographing apparatus 1 in side views. An optical head 900 is a measurement optical system for capturing an anterior eye image, a fundus surface image, and a tomographic image, and 950 is a moving unit that can move the optical head in the xyz direction using a motor (not shown). It is a stage part. Reference numeral 951 denotes a base unit incorporating a spectroscope described later.

  Reference numeral 925 denotes a personal computer (hereinafter also referred to as “personal computer”) that also serves as a control unit of the stage unit, and includes the image processing apparatus 100. Reference numeral 323 denotes a chin stand that fixes the subject's chin and forehead to promote fixation of the subject's eyes (eye to be examined). Reference numeral 324 denotes an external fixation target, which is used to fixate the eye of the subject. Further, the image processing apparatus 100 can be incorporated into the optical head 900 or the stage unit 950. In this case, the photographing apparatus 1 and the image processing apparatus 100 are integrally configured as a photographing apparatus.

FIG. 3 is a diagram illustrating a functional configuration of the image processing apparatus 100.
Reference numeral 1100 denotes a reconstruction unit as reconstruction means, which obtains a tomographic image of a predetermined range of the measured object based on interference light obtained by causing the return light of the measured light from the measured object to interfere with the reference light. The output value from the sensor is subjected to wave number transformation and fast Fourier transformation (FFT) processing, and reconstructed as a tomographic image (A scan image) in the depth direction at one point on the eye fundus.

  Also, 1200 is a generation unit that generates a two-dimensional image by selecting a predetermined pixel for each pixel value sequence from each pixel value sequence in the depth direction of the tomographic image obtained by the reconstruction unit 1100. Part.

  Reference numeral 1300 denotes an alignment unit as an alignment unit that aligns the two-dimensional image generated by the generation unit 1100, the surface image of the object to be measured, and the tomographic image. The alignment unit 1300 also has a function of aligning the two-dimensional image generated by the generation unit 1100 and the surface image of the object to be measured by template matching or the like. Here, template matching refers to a process in which feature points such as branch points of blood vessels are overlapped in each image. Also included is a process of matching the two-dimensional image generated by the generation unit 1100 and the surface image of the object to be measured so that the overlap between the images is evaluated and the correlation value becomes the highest.

  FIG. 4 is a diagram illustrating the configuration of the measurement optical system and the spectroscope of the photographing apparatus 1.

  First, the inside of the optical head 900 will be described.

  An objective lens 135-1 is installed facing the eye to be examined 107 as an example of the object to be measured. On the optical axis, the first dichroic mirror 132-1 and the second dichroic mirror 132-2 make the wavelength band into the optical path 351 of the OCT optical system, the optical path 352 for the fundus observation and the fixation lamp, and the optical path 353 for the anterior eye observation. Branches every time.

  Here, reference numerals 135-3 and 135-4 denote lenses, and 135-3 is driven by a motor (not shown) for focusing adjustment of the fixation target 191 and the fundus observation CCD 172.

  A perforated mirror 303 is disposed between the lens 135-4 and the third dichroic mirror 132-3, and the optical path 352 is branched into an optical path 352 and an optical path 354.

  The optical path 354 forms an illumination optical system that illuminates the fundus of the eye 107 to be examined. An LED light source 316 that is an illumination light source for fundus observation used for alignment of the eye 107 to be examined and a strobe tube 314 that is used for imaging the fundus of the eye 107 to be examined are installed.

  Here, 313 and 315 are condenser lenses, and 317 is a mirror. Illumination light from the LED light source 316 and the strobe tube 314 becomes a ring-shaped light flux by the ring slit 312 and is reflected by the perforated mirror 303 to illuminate the fundus 127 of the eye 107 to be examined. Here, reference numerals 309 and 311 denote lenses. The LED light source 316 is a light source having a central wavelength around 780 nm.

  After the perforated mirror 303 on the optical path 352, the third dichroic mirror 132-3 branches to the optical path to the fundus observation CCD 172 and the fixation lamp 191 for each wavelength band as described above.

  The CCD 172 has sensitivity at the center wavelength of the LED light source 316 that is illumination light for fundus observation, specifically, around 780 nm, and is connected to the CCD controller 102. On the other hand, the fixation target 191 generates visible light to promote fixation of the subject, and is connected to the fixation target control unit 103.

  The CCD control unit 102 and the fixation target control unit 103 are connected to the calculation unit 104, and data is input to and output from the personal computer 925 through the calculation unit 104.

  In the optical path 353, 135-2 is a lens, and 171 is an infrared CCD for anterior eye observation. The CCD 171 has sensitivity at a wavelength of illumination light for anterior eye observation (not shown), specifically, around 970 nm. In addition, an image split prism (not shown) is disposed in the optical path 353, and the distance in the z direction of the optical head 900 with respect to the eye 107 to be examined can be detected as a split image in the anterior eye observation image.

  The optical path 351 forms an OCT optical system as described above, and is used to capture a tomographic image of the retina of the eye 107 to be examined. More specifically, an interference signal for forming a tomographic image is obtained. Reference numeral 134 denotes an XY scanner for scanning light on the fundus. The XY scanner 134 is illustrated as a single mirror, but performs scanning in the XY biaxial directions. Reference numerals 135-5 and 135-6 denote lenses, and the lens 135-5 adjusts the focus of light from the light source 101 emitted from the fiber 131-2 connected to the optical coupler 131 on the fundus 127. Therefore, it is driven by a motor (not shown). With this focusing adjustment, the light from the fundus 127 is simultaneously focused on and incident on the tip of the fiber 131-2.

  Next, the configuration of the optical path from the light source 101, the reference optical system, and the spectroscope will be described.

  Reference numeral 101 denotes a light source, 132-4 denotes a mirror, 115 denotes dispersion compensation glass, 131 denotes the optical coupler described above, 131-1 to 4 denote a single mode optical fiber connected to the optical coupler, and 135-7 denotes a lens. , 180 is a spectroscope.

  The Michelson interference system is configured by these configurations. The light emitted from the light source 101 is split into measurement light on the optical fiber 131-2 side and optical fiber 131-3 reference light through an optical coupler 131 through an optical fiber 131-1.

  The measurement light is irradiated onto the fundus of the eye 107 to be observed through the OCT optical system optical path described above, and reaches the optical coupler 131 through the same optical path due to reflection and scattering by the retina.

  On the other hand, the reference light reaches the mirror 132-4 and is reflected through the optical fiber 131-3, the lens 135-7, and the dispersion compensation glass 115 inserted in order to match the dispersion of the measurement light and the reference light. Then, it returns on the same optical path and reaches the optical coupler 131.

  By the optical coupler 131, the measurement light and the reference light are combined to become interference light. Here, interference occurs when the optical path length of the measurement light and the optical path length of the reference light are substantially the same. The mirror 132-4 is held so as to be adjustable in the optical axis direction by a motor and a driving mechanism (not shown), and the optical path length of the reference light can be adjusted to the optical path length of the measurement light that changes depending on the eye 107 to be examined. The interference light is guided to the spectroscope 180 via the optical fiber 131-4.

  Reference numeral 139-1 denotes a measurement light side polarization adjusting unit provided in the optical fiber 131-2. Reference numeral 139-2 denotes a reference light side polarization adjusting unit provided in the optical fiber 131-3. These polarization adjusters have several parts that have the optical fiber routed in a loop shape, and rotate the loop-shaped part around the longitudinal direction of the fiber to twist the fiber and reference the measurement light It is possible to adjust and adjust the polarization state of light. In this apparatus, the polarization states of the measurement light and the reference light are adjusted and fixed in advance.

  The spectroscope 180 includes lenses 135-8 and 135-9, a diffraction grating 181, and a line sensor 182.

  The interference light emitted from the optical fiber 131-4 becomes substantially parallel light via the lens 135-8, is then split by the diffraction grating 181, and is imaged on the line sensor 182 by the lens 135-3. The output of the line sensor 182 is input to the personal computer 925.

  Next, the periphery of the light source 101 will be described. The light source 101 is an SLD (Super Luminescent Diode) which is a typical low coherent light source. The center wavelength is 855 nm and the wavelength bandwidth is about 100 nm. Here, the bandwidth is an important parameter because it affects the resolution of the obtained tomographic image in the optical axis direction. Further, although the SLD is selected here as the type of light source, it is only necessary to emit low-coherent light, and ASE (Amplified Spontaneous Emission) or the like can also be used. In view of measuring the eye, the center wavelength is preferably near infrared light. In addition, since the center wavelength affects the lateral resolution of the obtained tomographic image, it is desirable that the center wavelength be as short as possible. For both reasons, the center wavelength was set to 855 nm.

  In this embodiment, a Michelson interferometer is used as an interferometer, but a Mach-Zehnder interferometer may be used. It is desirable to use a Mach-Zehnder interferometer when the light amount difference is large according to the light amount difference between the measurement light and the reference light, and a Michelson interferometer when the light amount difference is relatively small.

  Next, an imaging method for the eye to be examined using the imaging apparatus will be described.

  First, the examiner seats a patient in front of the imaging device based on the present embodiment, and starts imaging the surface image of the fundus of the eye to be examined. The light emitted from the light source 316 becomes a ring-shaped light beam by the ring slit 312, is reflected by the perforated mirror 303, and illuminates the fundus 127 of the eye 107 to be examined. The reflected light beam from the fundus 127 passes through the perforated mirror 303 and forms an image on the CCD 172. The reflected light of the fundus 127 imaged by the CCD 172 is imaged as a surface image of the fundus by the CCD control unit 102 and transmitted to the image processing apparatus 100.

  Next, the imaging apparatus 1 captures a tomographic image of a desired site on the fundus of the eye 107 to be examined by controlling the XY scanner 134.

  The light emitted from the light source 101 passes through the optical fiber 131-1, and is divided into measurement light directed to the eye to be examined and reference light directed to the reference mirror 132-4 by the optical coupler 131.

  The measurement light traveling toward the eye to be examined passes through the optical fiber 131-2, is emitted from the end of the fiber, and enters the XY scanner 134. The measurement light deflected by the XY scanner 134 irradiates the fundus 127 to be examined via the optical system 135-1. Then, the reflected light reflected by the eye to be examined is returned to the optical coupler 131 along the reverse path.

  On the other hand, the reference light traveling toward the reference mirror passes through the optical fiber 131-3, is emitted from the fiber end, and reaches the reference mirror 132-4 through the collimating optical system 135-7 and the dispersion compensation optical system 115. The reference light reflected by the reference mirror 132-4 follows the reverse path and is returned to the optical coupler 131.

  The measurement light and the reference light that have returned to the optical coupler 131 interfere with each other, enter into the optical fiber 131-4 as interference light, are substantially collimated by the optical system 135-8, and enter the diffraction grating 181. The interference light input to the diffraction grating 181 is imaged on the line sensor 182 by the imaging lens 135-9, and an interference signal at one point on the fundus of the eye to be examined can be obtained.

  An output value as an image signal having interference information acquired by a plurality of elements of the line sensor 182 is output to the image processing apparatus 100. In addition, although the form which acquires the surface image of a fundus at once by the light emission of the strobe tube 314 has been described in FIG. 4, the fundus surface image may be obtained by the SLO type that scans the light emitted from the SLD light source.

  Next, the flow of the image processing method of the image processing apparatus 100 will be described with reference to FIG.

  After acquiring tomographic information at one point on the fundus of the eye to be examined, the imaging apparatus 1 drives the XY scanner 134 as a scanning means in the X direction to generate another point of interference light on the fundus of the eye to be examined. The other point of interference light is input to the reconstruction unit 1100 via the line sensor 182. The reconstruction unit 1100 forms a tomographic image (A scan image) in the depth direction at another point on the fundus of the eye to be examined. The position of the XY scanner 134 that captured the A-scan interference signal and the coordinates of the A-scan image are stored in association with each other.

  By continuously driving the XY scanner 134 in the X direction, the reconstruction unit 1100 reconstructs one horizontal tomographic image (B-scan image) of the fundus of the eye to be examined (S2000).

  Then, after the XY scanner 134 is driven in a certain amount in the Y direction, the above-described X direction scan is performed again, thereby regenerating a horizontal tomographic image (B scan image) of the fundus at another Y direction position on the eye fundus to be examined. The configuration unit 1100 is reconfigured. By repeating the driving of the XY scanner 134 in the Y direction, a plurality of tomographic images covering a predetermined range of the fundus 127 can be formed. In the imaging apparatus 1, the reconstruction unit 1100 forms 128 tomographic images by repeating the formation of the B scan image while performing a certain amount of micro drive 128 times in the Y direction. The reconstruction unit 1100 reconstructs (forms) a three-dimensional tomographic image from 128 tomographic images.

  Next, the generation unit 1200 generates a two-dimensional image of the retina from the tomographic image generated by the reconstruction unit 1100.

  As described above, the A scan image is a tomographic image in the depth direction at one point on the fundus of the eye to be examined, and is composed of a plurality of pieces of luminance information in the depth direction as shown in FIG.

  The two-dimensional tomographic image in FIG. 6 is a set of A-scan images. This two-dimensional tomographic image may be a B-scan image or a cross-section of a tomographic image reconstructed in three dimensions.

  For example, the photographing apparatus 1 uses a line sensor 182 having 2048 pixels, and the A-scan image Ai after FFT is composed of 1176 pixel values to form a pixel value string. Here, P0 indicates the value of the pixel value as the luminance information of the shallowest portion in the depth direction by the color density, and P1175 indicates the pixel value as the luminance information of the deepest portion in the depth direction. ing.

  The imaging apparatus obtains a pixel value at one point on the eye fundus as a representative intensity signal by selectively extracting one piece of luminance information from the plurality of pieces of luminance information. That is, one pixel value is selected from 1176 pixel values obtained by the A scan. Here, the generation unit 1200 may be configured to process the reconstructed tomographic image acquired by the acquisition unit 2000 (not shown) from the external device 3 to generate a two-dimensional image. In this case, an input is directly received from the acquisition unit 2000 without going through the reconstruction unit 1100.

  As shown in FIG. 7, the generation unit 1200 rearranges the luminance information of the tomographic image corresponding to each A scan in descending order of luminance. That is, the pixel values are ranked for each of the 1176 pixel value columns based on the magnitude relationship of the pixel values, and the pixel values are rearranged (S2010).

  Here, R0 is a pixel having the brightest luminance information as a pixel value, and R1175 is a pixel having the darkest luminance information as a pixel value. Since the luminance indicates the strength of interference, the pixel value also corresponds to the strength of interference.

  Then, the generation unit 1200 selects pixels Rx having a predetermined order. Here, the pixels in the predetermined order are pixels that are located at the xth position from the top after being rearranged in the descending order of luminance information.

  Since most of the tomographic images of the retina are composed of dark pixels, it is desirable that x is a pixel positioned higher than half the total number of pixels. For example, when an A-scan image composed of a pixel value sequence having a total pixel number of 1176 is used, the 118th pixel from the top corresponding to the upper 10% position is selected as the pixel Rx having a predetermined order. That is, the pixel value corresponding to the pixel Rx having a predetermined order is selected.

  The generation unit 1200 determines the luminance information of the pixels Rx in the predetermined order as the intensity information in the A scan. Then, by determining the intensity information for all the A-scan images, it is possible to obtain pixel values as intensity information for each point corresponding to the irradiation position of the scanned measurement light on the fundus 127 (S2020). In this case, a pixel value as intensity information is stored in a memory 3000 (not shown) corresponding to the two-dimensional coordinates for each irradiation position of the measurement light scanned on the fundus 127. Then, based on the pixel values corresponding to the coordinates stored in the memory 3000, a two-dimensional image (sometimes referred to as “intensity image” or “Intensity”) is generated, so that two retinal images as shown in FIG. A dimensional image I can be obtained (S2030).

  Note that the example has been described in which the generation unit 1200 generates a two-dimensional image after all the data is reconstructed by the reconstruction unit 1100. However, a configuration in which tomographic images reconstructed for each A scan are sequentially transmitted to the generation unit 1200, or a tomographic image reconstructed for each B scan may be sequentially transmitted to the generation unit 1200.

  This two-dimensional image is a surface image of the fundus obtained by the CCD 172, an image similar to the fundus image obtained by another fundus camera or SLO, and can visualize the fundus surface in a pseudo manner. In addition, since only effective information is selectively acquired from a plurality of luminance information, a suitable two-dimensional image is obtained without being influenced by a noise component included in the A-scan image or a dark area having low interference intensity. It is possible.

  Next, in this imaging apparatus, the registration unit 1300 performs the generated fundus surface image, tomographic image, and two-dimensional image and displays them on the monitor 928. As shown in FIG. 8, the fundus surface image S (Surface), the tomographic image Ti (Intensity), and the two-dimensional image I are displayed side by side on the monitor 928, and the two-dimensional image I and the surface image S are displayed on the tomographic image Ti. The acquisition position Li of (tomogram) is displayed in an overlapping manner.

  The image processing apparatus 100 generates 128 tomographic images. On the monitor 928, the tomographic image Ti (i = 0 to 128) as one selected cross section, or a three-dimensionally reconstructed tomographic image. A tomographic image Ti (in this case, an arbitrary number i is assigned) is displayed. The examiner can switch the tomographic image to be displayed by operating the input unit 929-1.929-2. Alternatively, the examiner operates the input unit 929-1.929-2 and scans the input unit 929-1.929-2 to select a location of the two-dimensional image I to be displayed. Can be selected.

  When the tomographic image Ti is switched, the display position of the acquisition position Li of the tomographic image Ti displayed on the two-dimensional image I and the surface image S is also updated. As a result, the examiner can easily know the position of the displayed tomographic image Ti on the fundus 127 to be examined because the image quality of the two-dimensional image I is good.

  In addition, since the image quality of the two-dimensional image is good, the tomographic image can be accurately selected by scanning the input units 929-1.929-2.

  Furthermore, since a tomographic image corresponding to position information on the two-dimensional image I can be obtained directly, there is no deviation in the positional relationship between the tomographic image of the retina and the intensity image. For this reason, it is possible to know exactly where the tomographic image was taken on the fundus.

  In addition, since the alignment is performed on the two-dimensional image I and the surface image S, the relationship between the position on the surface image S and the acquisition position of the tomographic image of the retina can be known more accurately via the information of the two-dimensional image I. Can do.

  In this embodiment, a two-dimensional image of the retina is generated based on the tomographic image of the fundus of the eye to be examined. However, even if a two-dimensional image of the anterior eye is generated based on the tomographic image of the anterior eye of the eye to be examined. good. In this case, the generated two-dimensional image is generated as an image similar to an anterior ocular plane image obtained by photographing the anterior ocular segment of the eye to be examined with a two-dimensional CCD camera or the like. It is also possible to take an image of skin or teeth.

  Further, since it is not necessary to integrate the images, it is possible to select information on the retina in a desired range in units of a single pixel.

  Therefore, a two-dimensional image with reduced unnecessary information can be obtained.

(Modification 1-1)
The generation unit 1200 determines the pixel value to be selected based on the sort process. However, the generation unit 1200 can be configured to select a predetermined layer of the retina such as NFL and sequentially rearrange pixel values in the layer to select the maximum value or the intermediate value. Then, a two-dimensional image of the retina is generated from the selected pixel value. In this case, it is possible to select information that is desired to be obtained more narrowly. Further, since it is not necessary to integrate the images, it is possible to select information on the retina in a desired range in units of a single pixel.

  Therefore, a two-dimensional image with reduced unnecessary information can be obtained.

(Modification 1-2)
The generation unit 1200 can be configured to remove pixel values equal to or less than a predetermined value in advance and sequentially rearrange the pixel values of the remaining retinal regions to select a maximum value or an intermediate value. Then, a two-dimensional image of the retina is generated from the selected pixel value. In this case, since the low pixel value region is a region where no interference image exists, it is possible to prevent unnecessary information from being selected by removing this region.

  In this case, the generation unit 1200 performs the sorting process by replacing pixel values below a predetermined position with 0 or the like. If 0 is included in the generated two-dimensional image, a warning that the shooting has failed is displayed on the monitor 928. Thus, the photographer can easily determine whether to perform re-shooting.

[Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIGS.

  The configuration of generation unit 1400 in FIG. In addition, other configurations are denoted by the same reference numerals and description thereof is omitted. The generation unit 1400 has a path for generating a two-dimensional image without going through the reconstruction unit 1100.

  The generation unit 1400 includes a path B that directly receives output values for each of a plurality of elements of the licensor 182 instead of the A scan image, in addition to the path A that performs the same processing as in the first embodiment. Then, an output value for each of the plurality of elements of the licensor 182 is selected for each irradiation position to generate a two-dimensional image.

  The first mode using the route A and the second mode using the route B are selected by a selection unit 1500 as selection means (not shown). For example, if the confirmation screen is immediately after shooting, the second mode is selected. If the image is to be confirmed in detail, the selection unit 1500 selects the first mode.

  The process when the first mode is selected is the same as that of the first embodiment, and the process when the second mode is selected will be described below according to the process flow of FIG.

  As described above, the licensor 182 has 2048 pixels and generates 2048 image signals. The generation unit 1400 acquires this image signal (S3000).

  Then, the generation unit 1400 obtains a representative intensity signal at one point on the eye fundus by selectively extracting one image signal from the plurality of image signals.

  In this case, the generation unit 1400 rearranges the plurality of image signals output from the line sensor 182 in descending order of signal level (S3100).

  Then, image signals of a predetermined order are selected and stored in the main memory 11 (S3200). Here, the image signal in the predetermined order is an image signal positioned nth from the head after the image signals are rearranged in descending order of the signal level.

  The generation unit 1400 determines the signal level of the image signals in the predetermined order as intensity information in the A scan.

  Then, the processes from S3000 to S3300 are repeated until all the A scans are completed. Thereby, intensity information at different points of the fundus 127 (corresponding to A scan) can be obtained. By constructing the intensity information as a two-dimensional image, a two-dimensional image of the retina as shown in FIG. 7 can be obtained (S3400). When the B mode is selected, processing can be performed faster than when the A mode is selected.

  The output of the licensor 182 may be A / D converted by the line sensor 182 or A / D converted by the receiving unit of the image processing apparatus 100.

(Modification 2-1)
In the case of implementing this embodiment in a so-called SS-OCT (Swept Source OCT) type in which the light source wavelength is changed, a single light receiving sensor can be used instead of the licensor 182.

  In this case, the interference signal is output from a single light receiving sensor for each scanning position on the fundus as 2048 image signals subjected to A / D conversion in a time division manner. The generation unit 1400 acquires the 2048 image signals, and (S3100) performs the following processing in the same manner. Thereby, even if it is what is called SS-OCT type, a two-dimensional image can be obtained at high speed. Note that the output of the light receiving sensor may be A / D converted by the light receiving sensor or A / D converted by the receiving unit of the image processing apparatus 100.

[Other Embodiments]
Although the description has been made with respect to the eye part, the present invention is not limited to this, and the imaging target may be the skin, the tooth part, the built-in inner wall, or the like.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

In view of the above problems, the present invention can easily know which position of the fundus of the eye to be examined is generated by generating the two-dimensional image without deteriorating the quality. Objective.

In order to achieve the above-described object, the present image generation apparatus is configured to obtain a tertiary of a predetermined range of the fundus based on interference light obtained by irradiating the fundus with measurement light and causing interference between return light from the fundus and reference light. An image processing apparatus for obtaining an original tomographic image, the generating means for generating a two-dimensional image based on a pixel value in the depth direction of the three-dimensional tomographic image, and a two-dimensional tomographic image included in the three-dimensional tomographic image Display control means for displaying on the display means the two-dimensional image generated by the generation means and the acquisition position of the two-dimensional tomographic image on the two-dimensional image, the display control means comprises in accordance with the change of the acquisition position, characterized be relocated to the corresponding two-dimensional tomographic image acquisition position after changing the two-dimensional tomographic image being the display.

According to the present invention, whether the tomographic image displayed that tomographic images of any position of the fundus, thereby easily known Rukoto.

The image processing apparatus 100 generates 128 tomographic images. On the monitor 928, the tomographic image Ti (i = 0 to 128) as one selected cross section, or a three-dimensionally reconstructed tomographic image. A tomographic image Ti (in this case, an arbitrary number i is assigned) is displayed. The examiner can switch the tomographic image to be displayed by operating the input unit 929-1.929-2. Alternatively, the tomographic image to be displayed by the examiner to operate the input unit 929-1.929-2 selects by operating the input unit 929-1.929-2 a portion of the two-dimensional image I to be displayed Can be selected.

In addition, since the image quality of the two-dimensional image is good, the tomographic image can be accurately selected by operating the input units 929-1.929-2.

Claims (7)

An acquisition means for acquiring a three-dimensional tomographic image of a predetermined range of the fundus based on interference light obtained by irradiating the fundus with measurement light and causing interference between return light from the fundus and reference light;
Selection means for selecting pixel values at predetermined positions from the top when arranged in the order of pixel value size for each pixel value sequence in the depth direction of each tomographic image included in the three-dimensional tomographic image;
Generating means for generating a two-dimensional image different from the tomographic image with the pixel value selected by the selecting means;
With
When the layer indicating the range in the depth direction for generating the two-dimensional image is selected, and when the layer indicating the range in the depth direction for generating the two-dimensional image is not selected An image generating apparatus characterized by being different from the predetermined order.   The predetermined order when the layer indicating the range in the depth direction for generating the two-dimensional image is selected is the highest order or intermediate order when the pixel values in the selected layer are arranged in order of size. The predetermined order when the layer indicating the range in the depth direction for generating the two-dimensional image is not selected is the case where the pixel values in the pixel value sequence of each tomographic image are arranged in order of size. The image generation apparatus according to claim 1, wherein the order is equivalent to the top 10% of positions.   The image generation apparatus according to claim 1, wherein the pixel value is a value indicating luminance. An acquisition step of acquiring a three-dimensional tomographic image of a predetermined range of the fundus based on interference light obtained by irradiating the fundus with measurement light and returning light from the fundus and reference light interfered with each other,
For each pixel value sequence in the depth direction of each tomographic image included in the three-dimensional tomographic image, a selection step of selecting pixel values at predetermined positions from the top when arranged in order of pixel value size;
A generation step of generating a two-dimensional image different from the tomographic image at the pixel value selected in the selection step;
With
When the layer indicating the range in the depth direction for generating the two-dimensional image is selected, and when the layer indicating the range in the depth direction for generating the two-dimensional image is not selected The image generation method according to claim 1, wherein the image generation method is different from the predetermined order.   The predetermined order when the layer indicating the range in the depth direction for generating the two-dimensional image is selected is the highest order or intermediate order when the pixel values in the selected layer are arranged in order of size. The predetermined order when the layer indicating the range in the depth direction for generating the two-dimensional image is not selected is the case where the pixel values in the pixel value sequence of each tomographic image are arranged in order of size. The image generation method according to claim 4, wherein the order corresponds to the top 10% of positions.   The image generation method according to claim 4, wherein the pixel value is a value indicating luminance.   A program that causes a computer to execute the image generation method according to any one of claims 4 to 6.