WO2023090044A1 - Processor for electronic endoscope and electronic endoscopic system - Google Patents

Processor for electronic endoscope and electronic endoscopic system Download PDF

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WO2023090044A1
WO2023090044A1 PCT/JP2022/039146 JP2022039146W WO2023090044A1 WO 2023090044 A1 WO2023090044 A1 WO 2023090044A1 JP 2022039146 W JP2022039146 W JP 2022039146W WO 2023090044 A1 WO2023090044 A1 WO 2023090044A1
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edge enhancement
electronic endoscope
control unit
image
captured image
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PCT/JP2022/039146
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French (fr)
Japanese (ja)
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篤 松野
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Hoya株式会社
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • A61B1/04—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor combined with photographic or television appliances
    • A61B1/045—Control thereof
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • A61B1/06—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor with illuminating arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
    • G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T1/00—General purpose image data processing

Definitions

  • the present invention relates to an electronic endoscope processor and an electronic endoscope system configured to acquire and process captured images of living tissue.
  • Electronic endoscopes are used to observe and treat living tissues inside the human body.
  • an image signal is amplified by an amplification factor adjusted using AGC (automatic gain control) in order to stabilize the brightness of an image obtained by imaging biological tissue using an electronic endoscope device. It is At that time, since the noise contained in the image signal is also amplified, the amplified noise is removed using a noise reduction filter.
  • AGC automatic gain control
  • Japanese Patent Application Laid-Open No. 2006-314504 describes an endoscope processor including an AGC circuit and a noise reduction filter circuit.
  • the AGC circuit amplifies the original image signal by a first amplification factor calculated based on the original image signal generated by the imaging element to generate the adjustment signal
  • the noise reduction filter is the first gain. is configured to reduce noise in the adjusted signal based on the amplification factor of Accordingly, it is possible to appropriately reduce noise in the image while stably maintaining the brightness of the image obtained by the endoscope.
  • edge enhancement processing when processing an image obtained by imaging a living tissue, edge enhancement processing (enhancement processing, etc.) may be performed in order to emphasize a region of interest such as a lesion.
  • edge enhancement processing enhancement processing, etc.
  • the noise portion of the image signal is enhanced by the edge enhancement processing in the latter stage, and the S/N ratio of the image signal is lowered.
  • the present invention is an electronic endoscope that can improve the S/N ratio of an image taken at a darker position than in the conventional art when acquiring an image of a living tissue and applying edge enhancement processing. It is an object of the present invention to provide a processor and an electronic endoscope system for a computer.
  • One aspect of the present invention is an electronic endoscope processor configured to acquire and process captured images of living tissue.
  • the processor shall: An electronic endoscope processor configured to acquire and process captured images of living tissue, a light source device that emits illumination light for the living tissue; a light source control unit that controls the intensity of the illumination light based on information about the brightness of the captured image; an automatic gain control unit that determines a gain based on the intensity of the illumination light and amplifies the captured image with the determined gain; an edge enhancement processing unit that performs edge enhancement processing on the captured image amplified by the automatic gain control unit; a control unit for controlling the edge enhancement processing unit such that the greater the gain determined by the automatic gain control unit, the lower the degree of enhancement of the edge enhancement processing; Prepare.
  • the electronic endoscope processor has a noise reduction processing unit that reduces noise components included in the captured image amplified by the automatic gain control unit,
  • the edge enhancement processing section may perform the edge enhancement processing on the captured image in which the noise component has been reduced.
  • the control section may control the noise reduction processing section so that the degree of reduction of the noise component is changed according to the gain determined by the automatic gain control section.
  • Another aspect of the present invention is the above electronic endoscope processor; an electronic endoscope that is connected to the electronic endoscope processor and has an imaging device that acquires a captured image of the living tissue.
  • the electronic endoscope processor and the electronic endoscope system described above when an image of a living tissue is acquired and edge enhancement processing is performed, the S/N ratio of the image when the living tissue in the distance is imaged is can be improved.
  • FIG. 2 is a block diagram showing an example of the configuration of an image processing unit shown in FIG. 1;
  • FIG. It is a figure explaining operation
  • FIG. 4 is a block diagram showing another example of the configuration of the image processing section;
  • the electronic endoscope processor of this embodiment is configured to irradiate a living tissue with illumination light from a light source device, image the living tissue, and obtain a captured image.
  • An electronic endoscope processor includes a light source controller and an automatic gain controller.
  • the light source control unit controls the intensity of illumination light based on information about the brightness of the captured image. Information related to the brightness of the captured image is not limited, but may be, for example, the brightness or illuminance of the captured image.
  • An AGC section (an example of an automatic gain control section) determines a gain (also referred to as "amplification factor") based on the intensity of illumination light, and amplifies a captured image with the determined gain.
  • the AGC unit amplifies the captured image by determining the amplification factor of the captured image based on the intensity of the illumination light.
  • the light source control unit and the AGC unit adjust the intensity of the illumination light from the light source device and the amplification factor of the captured image so that the brightness of the captured image obtained by imaging the living tissue is kept constant.
  • the captured image amplified by the automatic gain control section is subjected to edge enhancement processing by the edge enhancement processing section.
  • Edge enhancement methods are not limited, but examples include a method using a known spatial filter such as a Laplacian filter or a Sobel filter.
  • the electronic endoscope processor of this embodiment includes a control section that controls the edge enhancement processing section. This control section performs control such that the degree of enhancement (for example, sharpness) of the edge enhancement processing decreases as the gain determined by the automatic gain control section increases. By the action of this control section, it is possible to improve the S/N ratio of the captured image especially when the image is captured at a dark position.
  • the brightness of the captured image is maintained by increasing the amplification factor, but the noise superimposed on the captured image is also greatly amplified. Even if a noise reduction filter is provided in the subsequent stage, noise cannot be sufficiently removed. In that case, by increasing the amplification factor of the captured image, the degree of edge enhancement is lowered (weaken the edge enhancement or lowered the sharpness), thereby weakening the edge enhancement for the noise portion and reducing the overall As a result, the S/N ratio of the image can be improved.
  • the brightness of the captured image is maintained without increasing the amplification factor for the captured image, and the noise superimposed on the captured image is not greatly amplified.
  • the noise portion is not enhanced (that is, without lowering the S/N ratio). You can get a clear image.
  • FIG. 1 is a block diagram showing an example of the configuration of an electronic endoscope system 1 of this embodiment.
  • the electronic endoscope system 1 is a system specialized for medical use and includes an electronic scope (endoscope) 100 , a processor 200 and a monitor 300 .
  • the processor 200 has a system controller 21 .
  • the system controller 21 executes various programs stored in the memory 23 and comprehensively controls the entire electronic endoscope system 1 .
  • the system controller 21 is also connected to the operation panel 24 .
  • the system controller 21 changes each operation of the electronic endoscope system 1 and parameters for each operation according to instructions from the operator input to the operation panel 24 .
  • the system controller 21 outputs to each circuit in the electronic endoscope system 1 a clock pulse for adjusting the operation timing of each section.
  • the processor 200 has a light source device 201 .
  • the light source device 201 emits illumination light L for illuminating a subject such as living tissue in a body cavity.
  • the illumination light L includes white light, pseudo-white light, or special light.
  • the light source device 201 has a mode in which white light or pseudo-white light is always emitted as illumination light L, and a mode in which white light or pseudo-white light and special light are alternately emitted as illumination light L. It is preferable to select one and emit white light, pseudo-white light, or special light based on the selected mode.
  • White light is light that has a flat spectral intensity distribution in the visible light band
  • pseudo-white light is light that has a non-flat spectral intensity distribution and is a mixture of light in a plurality of wavelength bands.
  • the special light is light in a narrow wavelength band such as blue or green in the visible light band. Light in the blue or green wavelength band is used when emphasizing and observing a specific portion in living tissue.
  • the illumination light L emitted from the light source device 201 is condensed by the condensing lens 25 on the incident end surface of the LCB (Light Carrying Bundle) 11 and enters the LCB 11 .
  • LCB Light Carrying Bundle
  • the illumination light L that has entered the LCB 11 propagates through the LCB 11 .
  • the illumination light L propagated through the LCB 11 is emitted from the exit end surface of the LCB 11 arranged at the tip of the electronic scope 100 and irradiated onto the subject through the light distributing lens 12 .
  • Return light from the subject illuminated by the illumination light L from the light distribution lens 12 forms an optical image on the light receiving surface of the solid-state imaging device 14 via the objective lens 13 .
  • the solid-state imaging device 14 is a single-plate color CCD (Charge Coupled Device) image sensor having a Bayer pixel arrangement.
  • the solid-state imaging device 14 accumulates an optical image formed by each pixel on the light-receiving surface as an electric charge corresponding to the amount of light, and generates image signals of R (Red), G (Green), and B (Blue). Output.
  • the solid-state imaging device 14 is not limited to a CCD image sensor, and may be replaced with a CMOS (Complementary Metal Oxide Semiconductor) image sensor or other types of imaging devices.
  • the solid-state imaging device 14 may also be equipped with a complementary color filter.
  • a driver signal processing circuit 15 is provided in the connecting portion of the electronic scope 100 .
  • An image signal of an object is input from the solid-state imaging device 14 to the driver signal processing circuit 15 at predetermined frame intervals.
  • the frame period is, for example, 1/30 second.
  • the driver signal processing circuit 15 performs predetermined processing including A/D conversion on the image signal input from the solid-state imaging device 14 and outputs the processed image signal to the image processing section 22 of the processor 200 .
  • the image processing unit 22 performs predetermined image processing, which will be described later, to generate a video format signal and outputs it to the monitor 300 .
  • the driver signal processing circuit 15 also accesses the memory 16 to read the unique information of the electronic scope 100.
  • the unique information of the electronic scope 100 recorded in the memory 16 includes, for example, the number of pixels and sensitivity of the solid-state imaging device 14, operable frame rate, model number, and the like.
  • the driver signal processing circuit 15 outputs the unique information read from the memory 16 to the system controller 21 .
  • This unique information may include, for example, information unique to the solid-state imaging device 14 such as the number of pixels and resolution, as well as information regarding the optical system such as the angle of view, focal length, and depth of field.
  • the electronic endoscope processor 200 acquires luminance information (an example of information about brightness) of the image signal from the image processing unit 22, and controls the intensity of illumination light from the light source device 201 based on the luminance information.
  • a control unit 26 is provided.
  • the light source control unit 26 controls the intensity of the illumination light emitted from the light source device 201 to increase when the brightness is low, and to decrease the intensity of the illumination light emitted from the light source device 201 when the brightness is high. Then, the light source device 201 is controlled. Thereby, the brightness of the image signal received from the driver signal processing circuit 15 is controlled to be maintained constant.
  • the system controller 21 performs various calculations based on the unique information of the electronic scope 100 and generates control signals.
  • the system controller 21 uses the generated control signal to control the operation and timing of various circuits within the processor 200 so that the electronic scope 100 connected to the processor 200 can perform appropriate processing.
  • the system controller 21 supplies clock pulses to the driver signal processing circuit 15 .
  • the driver signal processing circuit 15 drives and controls the solid-state imaging device 14 in synchronization with the frame rate of the video processed by the processor 200 in accordance with clock pulses supplied from the system controller 21 .
  • FIG. 2 is a block diagram showing an example of the configuration of the image processing section 22.
  • the image processing section 22 includes an AGC section 221 , a pre-processing section 222 , a noise reduction processing section 223 , an edge enhancement processing section 224 , a post-processing section 225 and an intensity control section 226 .
  • the image processing unit 22 may be a software module formed as a module by the system controller 21 activating a program stored in the memory 23, or may be hardware configured with an FPGA (Field-Programmable Gate Array). It may be a wear module.
  • FPGA Field-Programmable Gate Array
  • the AGC unit 221 amplifies the image signal input from the driver signal processing circuit 15 in one frame cycle with the amplification factor controlled by the light source control unit 26 and outputs the amplified image signal to the pre-processing unit 222 .
  • the light source control section 26 controls the amplification degree in the AGC section 221 according to the brightness information of the image signal. For example, when the image is dark, the AGC section 221 is controlled so that the amplification factor (gain) for the image signal is increased.
  • the pre-processing unit 222 subjects the image signal amplified by the AGC unit 221 to predetermined signal processing such as demosaic processing and matrix calculation.
  • the noise reduction processing unit 223 is performed by removing high-frequency components contained in the image signal by, for example, a digital filter that performs a low-pass filter. Noise superimposed on the image signal is removed or suppressed by the noise reduction processing unit 223 .
  • the edge enhancement processing section 224 performs edge enhancement processing on the image signal input from the noise reduction processing section 223 .
  • a method of edge enhancement processing is not limited, but a method using a known spatial filter such as a Laplacian filter or a Sobel filter can be used.
  • the edge enhancement processing unit 224 is configured to be able to adjust the degree of edge enhancement (that is, edge enhancement strength or sharpness).
  • the intensity control unit 226 acquires amplification factor data from the AGC unit 221 and controls the edge enhancement intensity for the edge enhancement processing unit 224 .
  • the intensity of edge enhancement is adjusted by adjusting the kernel coefficient of the Laplacian filter, for example.
  • the post-processing unit 225 processes the image signal edge-enhanced by the edge enhancement processing unit 224 to generate screen data for monitor display, and converts the generated screen data for monitor display into a predetermined video format signal. Convert.
  • the converted video format signal is output to monitor 300 . As a result, the image of the subject is displayed on the display screen of monitor 300 .
  • FIG. 3A shows the operation in the ideal case
  • FIG. 3B shows the operation in the comparative example
  • FIG. 3C shows the operation in the example.
  • the ideal case of FIG. 3A is a state of sufficient brightness (for example, when imaging a nearby biological tissue as a subject), and all noise contained in the image signal is removed by noise reduction processing. is the case.
  • the comparative example in FIG. 3B is a case in which a distant biological tissue (a biological tissue in a dark position) is imaged as an object, and AGC is performed, but intensity control is not performed.
  • FIG. 3B shows the operation in the ideal case
  • FIG. 3B shows the operation in the comparative example
  • FIG. 3C shows the operation in the example.
  • FIG. 3C is a case of imaging a distant living tissue (a living tissue in a dark position) as a subject, as in FIG. 3B.
  • the embodiment of FIG. 3C differs from that of FIG. 3B in that processing is performed by the electronic endoscope system 1 configured as described above, that is, AGC is performed and intensity control is performed.
  • state S1 indicates the state of the image signal before AGC is performed
  • state S2 indicates the state of the image signal after AGC is performed
  • state S3 indicates the state of the image signal after noise reduction processing is performed.
  • the state S4 shows the state of the image signal after edge enhancement processing.
  • the signal level of the image signal in state S1 before AGC is performed is relatively high. Noise is superimposed on the image signal. Since the level of the image signal is relatively high, the amplification factor in AGC is set small. For example, if the amplification factor is 1 (same magnification), the signal level and noise level of the image signal in state S2 after AGC is performed are the same as in state S1.
  • the signal level of the image signal in state S1 before AGC is performed is relatively low.
  • the noise level is about the same as when the brightness is sufficient, so the S/N ratio is low.
  • the amplification factor in AGC is set large. For example, if the amplification factor is four times, the signal level and noise level of the image signal in state S2 after AGC is performed are both four times those in state S1.
  • noise reduction processing is performed, but since the noise level is amplified in state S2, the noise cannot be sufficiently removed unlike the case of FIG. 3A where the noise level is low.
  • edge enhancement processing is performed on an image signal containing noise, the edge enhancement is applied to the noise portion, resulting in deterioration of the image.
  • states S1 to S3 are the same as in FIG. 3B.
  • the intensity control unit 226 to which the data of the amplification factor is input controls the degree of edge enhancement to be lower than in the case of FIG. 3B.
  • state S4 it is possible to suppress edge enhancement in noise portions that have not been removed, and to improve the S/N ratio of the image compared to the case of FIG. 3B.
  • the electronic endoscope system 1 of the present embodiment can improve the S/N ratio of the image compared to the conventional one when imaging a living tissue in a dark position.
  • sufficient enhancement processing cannot be obtained as compared with the ideal case of FIG. Since the amplification factor set by the controller 226 is lowered, the degree of edge enhancement in the intensity control unit 226 does not need to be lowered. Therefore, as in the case of FIG. signal can be obtained.
  • the intensity control unit 226 changes the degree of noise component reduction (that is, the intensity of noise reduction processing) according to the amplification factor determined by the AGC unit 221.
  • the noise reduction processing unit 223 is also preferably controlled. For example, in the example shown in FIG. 3, if the amplification factor of AGC is quadrupled, the noise is also quadrupled. Therefore, it is preferable to increase the noise reduction strength within a range that does not affect the image signal. Since noise is reduced by increasing the strength of noise reduction, the noise becomes less conspicuous even if the strength of edge enhancement is increased, so there is room to increase the strength of edge enhancement processing. That is, by adjusting the strength of noise reduction processing and the strength of edge enhancement processing in a well-balanced manner according to the amplification factor in AGC section 221, the image signal sent to post-processing section 225 can be optimized.
  • the electronic endoscope processor and electronic endoscope system of the present invention have been described in detail above, the electronic endoscope processor and electronic endoscope system of the present invention are not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments. Of course, various improvements and changes may be made without departing from the gist of the above.
  • the present invention relates to the patent application of Japanese Patent Application No. 2021-186205 filed with the Japan Patent Office on November 16, 2021, and the entire contents of this application are incorporated herein by reference.

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Abstract

One embodiment of the present invention pertains to a processor that is for an electronic endoscope and that is configured to acquire and process an image captured of a living tissue. This processor for an electronic endoscope is configured to acquire and process an image captured of a living tissue, and comprises: a light source device which emits illumination light onto a living tissue; a light source control unit which controls the intensity of the illumination light on the basis of information about the brightness of the captured image; an automatic gain control unit which determines a gain on the basis of the intensity of the illumination light and amplifies the captured image according to the determined gain; an edge enhancement processing unit which performs edge enhancement processing on the captured image amplified by the automatic gain control unit; and a control unit which controls the edge enhancement processing unit such that the level of enhancement in the edge enhancement processing becomes lower as the gain determined by the automatic gain control unit is greater.

Description

電子内視鏡用プロセッサ及び電子内視鏡システムElectronic endoscope processor and electronic endoscope system
　本発明は、生体組織の撮像画像を取得して処理するように構成された電子内視鏡用プロセッサ及び電子内視鏡システムに関する。 The present invention relates to an electronic endoscope processor and an electronic endoscope system configured to acquire and process captured images of living tissue.
　人体内部の生体組織の観察や治療に電子内視鏡装置が使用されている。従来、電子内視鏡装置を用いて生体組織を撮像して得られる画像の明るさを安定させるためにＡＧＣ（automatic gain control）を用いて調整された増幅率により画像信号を増幅させることが知られている。その際、画像信号に含まれるノイズも増幅されることから、この増幅されたノイズをノイズ低減用のフィルタを用いて除去することなどが行われる。 　Electronic endoscopes are used to observe and treat living tissues inside the human body. Conventionally, it is known that an image signal is amplified by an amplification factor adjusted using AGC (automatic gain control) in order to stabilize the brightness of an image obtained by imaging biological tissue using an electronic endoscope device. It is At that time, since the noise contained in the image signal is also amplified, the amplified noise is removed using a noise reduction filter.
　例えば特開２００６－３１４５０４号公報には、ＡＧＣ回路とノイズ低減フィルタ回路を備えた内視鏡用プロセッサが記載されている。この内視鏡用プロセッサでは、撮像素子が生成する原画像信号に基づいて算出された第１の増幅率によりＡＧＣ回路が原画像信号を増幅して調整信号を生成し、ノイズ低減フィルタが第１の増幅率に基づいて調整信号のノイズを低減化させるように構成される。それによって、内視鏡による画像明るさを安定的に保ちながら、画像のノイズを適切に低減化することができる、とされている。 For example, Japanese Patent Application Laid-Open No. 2006-314504 describes an endoscope processor including an AGC circuit and a noise reduction filter circuit. In this endoscope processor, the AGC circuit amplifies the original image signal by a first amplification factor calculated based on the original image signal generated by the imaging element to generate the adjustment signal, and the noise reduction filter is the first gain. is configured to reduce noise in the adjusted signal based on the amplification factor of Accordingly, it is possible to appropriately reduce noise in the image while stably maintaining the brightness of the image obtained by the endoscope.
　ところで、生体組織を撮像して得られる画像を処理する際には、病変部等の注目部位を強調するためにエッジ強調処理（エンハンス処理等）を行う場合がある。その際、従来の内視鏡用プロセッサでは、画像が暗い場合にはＡＧＣ回路における増幅率が高くなり、それによって画像信号に重畳するノイズも増幅されるため、ノイズ低減フィルタによりノイズが十分に除去できない場合がある。その場合、後段のエッジ強調処理によって画像信号のノイズ部分が強調される処理がなされ、画像信号のＳ／Ｎ比を低下させてしまうという課題があった。 By the way, when processing an image obtained by imaging a living tissue, edge enhancement processing (enhancement processing, etc.) may be performed in order to emphasize a region of interest such as a lesion. At that time, in the conventional endoscope processor, when the image is dark, the amplification factor in the AGC circuit becomes high, and the noise superimposed on the image signal is also amplified, so the noise is sufficiently removed by the noise reduction filter. Sometimes you can't. In this case, there is a problem that the noise portion of the image signal is enhanced by the edge enhancement processing in the latter stage, and the S/N ratio of the image signal is lowered.
　そこで、本発明は、生体組織の撮像画像を取得してエッジ強調処理を施す際、従来に比べて暗い位置で撮像された場合の画像のＳ／Ｎ比を向上させることができる電子内視鏡用プロセッサ及び電子内視鏡システムを提供することを目的とする。 Therefore, the present invention is an electronic endoscope that can improve the S/N ratio of an image taken at a darker position than in the conventional art when acquiring an image of a living tissue and applying edge enhancement processing. It is an object of the present invention to provide a processor and an electronic endoscope system for a computer.
　本発明の一態様は、生体組織の撮像画像を取得して処理するように構成された電子内視鏡用プロセッサである。当該プロセッサは、
　生体組織の撮像画像を取得して処理するように構成された電子内視鏡用プロセッサであって、
　前記生体組織に対する照明光を出射する光源装置と、
　前記撮像画像の明るさに関する情報に基づいて前記照明光の強度を制御する光源制御部と、
　前記照明光の強度に基づいて利得を決定し、決定した前記利得によって前記撮像画像を増幅する自動利得制御部と、
　前記自動利得制御部によって増幅された前記撮像画像に対してエッジ強調処理を行うエッジ強調処理部と、
　前記自動利得制御部によって決定された利得が大きいほど前記エッジ強調処理の強調の程度が低下するように、前記エッジ強調処理部を制御する制御部と、
　を備える。 One aspect of the present invention is an electronic endoscope processor configured to acquire and process captured images of living tissue. The processor shall:
An electronic endoscope processor configured to acquire and process captured images of living tissue,
a light source device that emits illumination light for the living tissue;
a light source control unit that controls the intensity of the illumination light based on information about the brightness of the captured image;
an automatic gain control unit that determines a gain based on the intensity of the illumination light and amplifies the captured image with the determined gain;
an edge enhancement processing unit that performs edge enhancement processing on the captured image amplified by the automatic gain control unit;
a control unit for controlling the edge enhancement processing unit such that the greater the gain determined by the automatic gain control unit, the lower the degree of enhancement of the edge enhancement processing;
Prepare.
　上記電子内視鏡用プロセッサは、前記自動利得制御部によって増幅された前記撮像画像に含まれるノイズ成分を低減するノイズ低減処理部を有し、
　前記エッジ強調処理部は、前記ノイズ成分が低減された前記撮像画像に対して前記エッジ強調処理を行ってもよい。 The electronic endoscope processor has a noise reduction processing unit that reduces noise components included in the captured image amplified by the automatic gain control unit,
The edge enhancement processing section may perform the edge enhancement processing on the captured image in which the noise component has been reduced.
　前記制御部は、前記自動利得制御部によって決定された利得に応じて前記ノイズ成分の低減度合いが変更されるように、前記ノイズ低減処理部を制御してもよい。 The control section may control the noise reduction processing section so that the degree of reduction of the noise component is changed according to the gain determined by the automatic gain control section.
　本発明の別の態様は、上記電子内視鏡用プロセッサと、
　前記電子内視鏡用プロセッサに接続され、前記生体組織の撮像画像を取得する撮像素子を備えた電子内視鏡と、を備える電子内視鏡システムである。 Another aspect of the present invention is the above electronic endoscope processor;
an electronic endoscope that is connected to the electronic endoscope processor and has an imaging device that acquires a captured image of the living tissue.
　上述の電子内視鏡用プロセッサ及び電子内視鏡システムによれば、生体組織の撮像画像を取得してエッジ強調処理を施す際、遠くにある生体組織を撮像した場合の画像のＳ／Ｎ比を向上させることができる。 According to the electronic endoscope processor and the electronic endoscope system described above, when an image of a living tissue is acquired and edge enhancement processing is performed, the S/N ratio of the image when the living tissue in the distance is imaged is can be improved.
一実施形態の電子内視鏡システムの構成の一例を示すブロック図である。It is a block diagram showing an example of composition of an electronic endoscope system of one embodiment. 図１に示す画像処理部の構成の一例を示すブロック図である。2 is a block diagram showing an example of the configuration of an image processing unit shown in FIG. 1; FIG. 一実施形態の電子内視鏡システムにおいて画像処理部の動作を説明する図である。It is a figure explaining operation|movement of the image-processing part in the electronic endoscope system of one Embodiment. 一実施形態の電子内視鏡システムにおいて画像処理部の動作を説明する図である。It is a figure explaining operation|movement of the image-processing part in the electronic endoscope system of one Embodiment. 一実施形態の電子内視鏡システムにおいて画像処理部の動作を説明する図である。It is a figure explaining operation|movement of the image-processing part in the electronic endoscope system of one Embodiment. 画像処理部の構成の別の例を示すブロック図である。FIG. 4 is a block diagram showing another example of the configuration of the image processing section;
　本実施形態の電子内視鏡用プロセッサは、光源装置により照明光を生体組織に照射し、生体組織を撮像して撮像画像を取得するように構成される。電子内視鏡用プロセッサは、光源制御部と自動利得制御部を備える。
　光源制御部は、撮像画像の明るさに関する情報に基づいて照明光の強度を制御する。撮像画像の明るさに関する情報は限定しないが、例えば、撮像画像の輝度や照度である。
　ＡＧＣ部（自動利得制御部の一例）は、照明光の強度に基づいて利得（「増幅率」ともいう。）を決定し、決定した利得によって撮像画像を増幅する。つまり、ＡＧＣ部は、照明光の強度に基づいて撮像画像の増幅率を決定して撮像画像を増幅する。
　光源制御部とＡＧＣ部により、生体組織を撮像して得られる撮像画像の明るさが一定に保たれるように、光源装置による照明光の強度と撮像画像の増幅率が調整される。 The electronic endoscope processor of this embodiment is configured to irradiate a living tissue with illumination light from a light source device, image the living tissue, and obtain a captured image. An electronic endoscope processor includes a light source controller and an automatic gain controller.
The light source control unit controls the intensity of illumination light based on information about the brightness of the captured image. Information related to the brightness of the captured image is not limited, but may be, for example, the brightness or illuminance of the captured image.
An AGC section (an example of an automatic gain control section) determines a gain (also referred to as "amplification factor") based on the intensity of illumination light, and amplifies a captured image with the determined gain. In other words, the AGC unit amplifies the captured image by determining the amplification factor of the captured image based on the intensity of the illumination light.
The light source control unit and the AGC unit adjust the intensity of the illumination light from the light source device and the amplification factor of the captured image so that the brightness of the captured image obtained by imaging the living tissue is kept constant.
　自動利得制御部によって増幅された撮像画像は、エッジ強調処理部によってエッジ強調処理が施される。エッジ強調方法は限定しないが、例としてラプラシアンフィルタやソーベルフィルタ等の公知の空間フィルタを用いる方法が挙げられる。エッジ強調処理によって、撮像画像中に例えば病変部などの注目すべき部位が含まれている場合に、当該部位を強調して表示させることができる。
　本実施形態の電子内視鏡用プロセッサは、エッジ強調処理部を制御する制御部を備える。この制御部は、自動利得制御部によって決定された利得が大きいほど前記エッジ強調処理の強調の程度（例えば先鋭度）が低下するように制御する。この制御部の作用によって、特に暗い位置で撮像された場合の撮像画像のＳ／Ｎ比を向上させることができる。 The captured image amplified by the automatic gain control section is subjected to edge enhancement processing by the edge enhancement processing section. Edge enhancement methods are not limited, but examples include a method using a known spatial filter such as a Laplacian filter or a Sobel filter. By edge enhancement processing, when a part of interest such as a lesion is included in the captured image, the part can be displayed in an emphasized manner.
The electronic endoscope processor of this embodiment includes a control section that controls the edge enhancement processing section. This control section performs control such that the degree of enhancement (for example, sharpness) of the edge enhancement processing decreases as the gain determined by the automatic gain control section increases. By the action of this control section, it is possible to improve the S/N ratio of the captured image especially when the image is captured at a dark position.
　すなわち、被写体として遠くにある生体組織（暗い位置にある生体組織）を撮像した場合、撮像画像の明るさは増幅率を大きくすることで維持されるが、撮像画像の重畳するノイズも大きく増幅されて後段にノイズ低減フィルタを設ける場合でもノイズが十分に除去できない。その場合に、撮像画像の増幅率を大きくした分、エッジ強調の程度を低下させる（エッジ強調を弱める、あるいは先鋭度を下げる）ように制御することで、ノイズ部分に対するエッジ強調が弱められ、全体として画像のＳ／Ｎ比を向上させることができる。
　また、その生体組織を近くで撮像する場合には、撮像画像に対する増幅率を大きくしなくても撮像画像の明るさが維持され、撮像画像の重畳するノイズも大きく増幅されることはない。その場合、エッジ強調の程度を低下させない（エッジ強調を強める、あるいは先鋭度を上げる）ように制御することで、ノイズ部分が強調されることなく（つまり、Ｓ／Ｎ比を低下させることなく）はっきりとした画像を得ることができる。 That is, when imaging a distant biological tissue (a biological tissue in a dark position) as a subject, the brightness of the captured image is maintained by increasing the amplification factor, but the noise superimposed on the captured image is also greatly amplified. Even if a noise reduction filter is provided in the subsequent stage, noise cannot be sufficiently removed. In that case, by increasing the amplification factor of the captured image, the degree of edge enhancement is lowered (weaken the edge enhancement or lowered the sharpness), thereby weakening the edge enhancement for the noise portion and reducing the overall As a result, the S/N ratio of the image can be improved.
Further, when the living tissue is imaged nearby, the brightness of the captured image is maintained without increasing the amplification factor for the captured image, and the noise superimposed on the captured image is not greatly amplified. In that case, by controlling so as not to lower the degree of edge enhancement (increase edge enhancement or increase sharpness), the noise portion is not enhanced (that is, without lowering the S/N ratio). You can get a clear image.
　以下、本実施形態の電子内視鏡システムについて図面を参照しながら詳細に説明する。
　図１は、本実施形態の電子内視鏡システム１の構成の一例を示すブロック図である。図１に示されるように、電子内視鏡システム１は、医療用に特化されたシステムであり、電子スコープ（内視鏡）１００、プロセッサ２００及びモニタ３００を備えている。 Hereinafter, the electronic endoscope system of this embodiment will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an example of the configuration of an electronic endoscope system 1 of this embodiment. As shown in FIG. 1 , the electronic endoscope system 1 is a system specialized for medical use and includes an electronic scope (endoscope) 100 , a processor 200 and a monitor 300 .
　プロセッサ２００は、システムコントローラ２１を備えている。システムコントローラ２１は、メモリ２３に記憶された各種プログラムを実行し、電子内視鏡システム１全体を統合的に制御する。また、システムコントローラ２１は、操作パネル２４に接続されている。システムコントローラ２１は、操作パネル２４に入力される術者からの指示に応じて、電子内視鏡システム１の各動作及び各動作のためのパラメータを変更する。システムコントローラ２１は、各部の動作のタイミングを調整するクロックパルスを電子内視鏡システム１内の各回路に出力する。 The processor 200 has a system controller 21 . The system controller 21 executes various programs stored in the memory 23 and comprehensively controls the entire electronic endoscope system 1 . The system controller 21 is also connected to the operation panel 24 . The system controller 21 changes each operation of the electronic endoscope system 1 and parameters for each operation according to instructions from the operator input to the operation panel 24 . The system controller 21 outputs to each circuit in the electronic endoscope system 1 a clock pulse for adjusting the operation timing of each section.
　プロセッサ２００は、光源装置２０１を備えている。光源装置２０１は、体腔内の生体組織等の被写体を照明するための照明光Ｌを出射する。照明光Ｌは、白色光、擬似白色光、あるいは特殊光を含む。一実施形態によれば、光源装置２０１は、白色光あるいは擬似白色光を照明光Ｌとして常時射出するモードと、白色光あるいは擬似白色光と、特殊光が交互に照明光Ｌとして射出するモードの一方を選択し、選択したモードに基づいて、白色光、擬似白色光、あるいは特殊光を射出することが好ましい。白色光は、可視光帯域においてフラットな分光強度分布を有する光であり、擬似白色光は、分光強度分布はフラットではなく、複数の波長帯域の光が混色された光である。特殊光は、可視光帯域の中の青色あるいは緑色等の狭い波長帯域の光である。青色あるいは緑色の波長帯域の光は、生体組織中の特定の部分を強調して観察する時に用いられる。光源装置２０１から出射した照明光Ｌは、集光レンズ２５によりＬＣＢ（Light Carrying Bundle）１１の入射端面に集光されてＬＣＢ１１内に入射される。 The processor 200 has a light source device 201 . The light source device 201 emits illumination light L for illuminating a subject such as living tissue in a body cavity. The illumination light L includes white light, pseudo-white light, or special light. According to one embodiment, the light source device 201 has a mode in which white light or pseudo-white light is always emitted as illumination light L, and a mode in which white light or pseudo-white light and special light are alternately emitted as illumination light L. It is preferable to select one and emit white light, pseudo-white light, or special light based on the selected mode. White light is light that has a flat spectral intensity distribution in the visible light band, and pseudo-white light is light that has a non-flat spectral intensity distribution and is a mixture of light in a plurality of wavelength bands. The special light is light in a narrow wavelength band such as blue or green in the visible light band. Light in the blue or green wavelength band is used when emphasizing and observing a specific portion in living tissue. The illumination light L emitted from the light source device 201 is condensed by the condensing lens 25 on the incident end surface of the LCB (Light Carrying Bundle) 11 and enters the LCB 11 .
　ＬＣＢ１１内に入射された照明光Ｌは、ＬＣＢ１１内を伝播する。ＬＣＢ１１内を伝播した照明光Ｌは、電子スコープ１００の先端に配置されたＬＣＢ１１の射出端面から射出され、配光レンズ１２を介して被写体に照射される。配光レンズ１２からの照明光Ｌによって照明された被写体からの戻り光は、対物レンズ１３を介して固体撮像素子１４の受光面上で光学像を結ぶ。 The illumination light L that has entered the LCB 11 propagates through the LCB 11 . The illumination light L propagated through the LCB 11 is emitted from the exit end surface of the LCB 11 arranged at the tip of the electronic scope 100 and irradiated onto the subject through the light distributing lens 12 . Return light from the subject illuminated by the illumination light L from the light distribution lens 12 forms an optical image on the light receiving surface of the solid-state imaging device 14 via the objective lens 13 .
　固体撮像素子１４は、ベイヤ型画素配置を有する単板式カラーＣＣＤ（Charge Coupled Device）イメージセンサである。固体撮像素子１４は、受光面上の各画素で結像した光学像を光量に応じた電荷として蓄積して、Ｒ（Red）、Ｇ（Green）、Ｂ（Blue）の画像信号を生成して出力する。なお、固体撮像素子１４は、ＣＣＤイメージセンサに限らず、ＣＭＯＳ（Complementary Metal Oxide Semiconductor）イメージセンサやその他の種類の撮像装置に置き換えられてもよい。固体撮像素子１４はまた、補色系フィルタを搭載したものであってもよい。 The solid-state imaging device 14 is a single-plate color CCD (Charge Coupled Device) image sensor having a Bayer pixel arrangement. The solid-state imaging device 14 accumulates an optical image formed by each pixel on the light-receiving surface as an electric charge corresponding to the amount of light, and generates image signals of R (Red), G (Green), and B (Blue). Output. Note that the solid-state imaging device 14 is not limited to a CCD image sensor, and may be replaced with a CMOS (Complementary Metal Oxide Semiconductor) image sensor or other types of imaging devices. The solid-state imaging device 14 may also be equipped with a complementary color filter.
　電子スコープ１００の接続部内には、ドライバ信号処理回路１５が備えられている。ドライバ信号処理回路１５には、固体撮像素子１４から被写体の画像信号が所定のフレーム周期で入力される。フレーム周期は、例えば、１／３０秒である。ドライバ信号処理回路１５は、固体撮像素子１４から入力される画像信号に対してＡ／Ｄ変換を含む所定の処理を施してプロセッサ２００の画像処理部２２に出力する。
　画像処理部２２は、後述する所定の画像処理を行ってビデオフォーマット信号を生成し、モニタ３００に出力する。 A driver signal processing circuit 15 is provided in the connecting portion of the electronic scope 100 . An image signal of an object is input from the solid-state imaging device 14 to the driver signal processing circuit 15 at predetermined frame intervals. The frame period is, for example, 1/30 second. The driver signal processing circuit 15 performs predetermined processing including A/D conversion on the image signal input from the solid-state imaging device 14 and outputs the processed image signal to the image processing section 22 of the processor 200 .
The image processing unit 22 performs predetermined image processing, which will be described later, to generate a video format signal and outputs it to the monitor 300 .
　ドライバ信号処理回路１５は、また、メモリ１６にアクセスして電子スコープ１００の固有情報を読み出す。メモリ１６に記録される電子スコープ１００の固有情報には、例えば、固体撮像素子１４の画素数や感度、動作可能なフレームレート、型番等が含まれる。ドライバ信号処理回路１５は、メモリ１６から読み出された固有情報をシステムコントローラ２１に出力する。この固有情報には、例えば、固体撮像素子１４の画素数や解像度等の素子特有の情報、さらには、光学系に関する画角、焦点距離、被写界深度等の情報も含まれてもよい。 The driver signal processing circuit 15 also accesses the memory 16 to read the unique information of the electronic scope 100. The unique information of the electronic scope 100 recorded in the memory 16 includes, for example, the number of pixels and sensitivity of the solid-state imaging device 14, operable frame rate, model number, and the like. The driver signal processing circuit 15 outputs the unique information read from the memory 16 to the system controller 21 . This unique information may include, for example, information unique to the solid-state imaging device 14 such as the number of pixels and resolution, as well as information regarding the optical system such as the angle of view, focal length, and depth of field.
　電子内視鏡用プロセッサ２００には、画像処理部２２から画像信号の輝度情報（明るさに関する情報の一例）を取得し、その輝度情報に基づいて光源装置２０１の照明光の強度を制御する光源制御部２６を備える。
　光源制御部２６は、明るさが少ない場合には光源装置２０１から照射される照明光の強度が高くなり、明るさが大きい場合には光源装置２０１から照射される照明光の強度が低くなるように、光源装置２０１を制御する。それによって、ドライバ信号処理回路１５から受信する画像信号の明るさが一定に維持されるように制御される。 The electronic endoscope processor 200 acquires luminance information (an example of information about brightness) of the image signal from the image processing unit 22, and controls the intensity of illumination light from the light source device 201 based on the luminance information. A control unit 26 is provided.
The light source control unit 26 controls the intensity of the illumination light emitted from the light source device 201 to increase when the brightness is low, and to decrease the intensity of the illumination light emitted from the light source device 201 when the brightness is high. Then, the light source device 201 is controlled. Thereby, the brightness of the image signal received from the driver signal processing circuit 15 is controlled to be maintained constant.
　システムコントローラ２１は、電子スコープ１００の固有情報に基づいて各種演算を行い、制御信号を生成する。システムコントローラ２１は、生成された制御信号を用いて、プロセッサ２００に接続されている電子スコープ１００に適した処理がなされるようにプロセッサ２００内の各種回路の動作やタイミングを制御する。 The system controller 21 performs various calculations based on the unique information of the electronic scope 100 and generates control signals. The system controller 21 uses the generated control signal to control the operation and timing of various circuits within the processor 200 so that the electronic scope 100 connected to the processor 200 can perform appropriate processing.
　システムコントローラ２１は、ドライバ信号処理回路１５にクロックパルスを供給する。ドライバ信号処理回路１５は、システムコントローラ２１から供給されるクロックパルスに従って、固体撮像素子１４をプロセッサ２００側で処理される映像のフレームレートに同期したタイミングで駆動制御する。 The system controller 21 supplies clock pulses to the driver signal processing circuit 15 . The driver signal processing circuit 15 drives and controls the solid-state imaging device 14 in synchronization with the frame rate of the video processed by the processor 200 in accordance with clock pulses supplied from the system controller 21 .
　次に、図２を参照して、画像処理部２２についてさらに説明する。図２は、画像処理部２２の構成の一例を示すブロック図である。
　図２に示すように、画像処理部２２は、ＡＧＣ部２２１、前段処理部２２２、ノイズ低減処理部２２３、エッジ強調処理部２２４、後段処理部２２５、及び、強度制御部２２６を備える。
　なお、画像処理部２２は、システムコントローラ２１がメモリ２３に記憶されたプログラムを起動してモジュールとして形成するソフトウェアモジュールであってもよく、また、ＦＰＧＡ（Field-Programmable gate Array）で構成されたハードウェアモジュールであってもよい。 Next, the image processing section 22 will be further described with reference to FIG. FIG. 2 is a block diagram showing an example of the configuration of the image processing section 22. As shown in FIG.
As shown in FIG. 2 , the image processing section 22 includes an AGC section 221 , a pre-processing section 222 , a noise reduction processing section 223 , an edge enhancement processing section 224 , a post-processing section 225 and an intensity control section 226 .
Note that the image processing unit 22 may be a software module formed as a module by the system controller 21 activating a program stored in the memory 23, or may be hardware configured with an FPGA (Field-Programmable Gate Array). It may be a wear module.
　ＡＧＣ部２２１は、ドライバ信号処理回路１５から１フレーム周期で入力される画像信号を光源制御部２６によって制御される増幅率によって増幅して、前段処理部２２２に出力する。光源制御部２６は、画像信号の明るさ情報に応じてＡＧＣ部２２１における増幅度を制御する。例えば、暗い画像である場合には、画像信号に対する増幅率（利得）が大きくなるようにＡＧＣ部２２１が制御される。 The AGC unit 221 amplifies the image signal input from the driver signal processing circuit 15 in one frame cycle with the amplification factor controlled by the light source control unit 26 and outputs the amplified image signal to the pre-processing unit 222 . The light source control section 26 controls the amplification degree in the AGC section 221 according to the brightness information of the image signal. For example, when the image is dark, the AGC section 221 is controlled so that the amplification factor (gain) for the image signal is increased.
　前段処理部２２２は、ＡＧＣ部２２１によって増幅された画像信号に対してデモザイク処理、マトリックス演算等の所定の信号処理を施す。
　ノイズ低減処理部２２３は、例えばローパスフィルタを行うデジタルフィルタによって画像信号に含まれる高周波成分を除去することにより行われる。ノイズ低減処理部２２３によって、画像信号に重畳されているノイズが除去又は抑制される。
　エッジ強調処理部２２４は、ノイズ低減処理部２２３から入力される画像信号に対してエッジ強調処理を行う。エッジ強調処理の方法は限定しないが、ラプラシアンフィルタやソーベルフィルタ等の公知の空間フィルタを用いる方法が挙げられる。エッジ強調処理部２２４では、エッジ強調の程度（つまり、エッジ強調の強度、あるいは、先鋭度ともいう。）を調整可能に構成されている。 The pre-processing unit 222 subjects the image signal amplified by the AGC unit 221 to predetermined signal processing such as demosaic processing and matrix calculation.
The noise reduction processing unit 223 is performed by removing high-frequency components contained in the image signal by, for example, a digital filter that performs a low-pass filter. Noise superimposed on the image signal is removed or suppressed by the noise reduction processing unit 223 .
The edge enhancement processing section 224 performs edge enhancement processing on the image signal input from the noise reduction processing section 223 . A method of edge enhancement processing is not limited, but a method using a known spatial filter such as a Laplacian filter or a Sobel filter can be used. The edge enhancement processing unit 224 is configured to be able to adjust the degree of edge enhancement (that is, edge enhancement strength or sharpness).
　強度制御部２２６は、ＡＧＣ部２２１から増幅率のデータを取得し、エッジ強調処理部２２４に対するエッジ強調の強度に対する制御を行う。エッジ強調処理部２２４を、ラプラシアンフィルタを用いて構成する場合には、例えばラプラシアンフィルタのカーネルの係数を調整することによりエッジ強調の強度が調整される。 The intensity control unit 226 acquires amplification factor data from the AGC unit 221 and controls the edge enhancement intensity for the edge enhancement processing unit 224 . When the edge enhancement processing unit 224 is configured using a Laplacian filter, the intensity of edge enhancement is adjusted by adjusting the kernel coefficient of the Laplacian filter, for example.
　後段処理部２２５は、エッジ強調処理部２２４によりエッジ強調が施された画像信号を処理してモニタ表示用の画面データを生成し、生成されたモニタ表示用の画面データを所定のビデオフォーマット信号に変換する。変換されたビデオフォーマット信号は、モニタ３００に出力される。これにより、被写体の画像がモニタ３００の表示画面に表示される。 The post-processing unit 225 processes the image signal edge-enhanced by the edge enhancement processing unit 224 to generate screen data for monitor display, and converts the generated screen data for monitor display into a predetermined video format signal. Convert. The converted video format signal is output to monitor 300 . As a result, the image of the subject is displayed on the display screen of monitor 300 .
　次に、図３Ａ～図３Ｃを参照して、本実施形態の電子内視鏡システム１における画像処理部２２の動作について説明する。図３Ａは理想的な場合の動作であり、図３Ｂは比較例の動作であり、図３Ｃは実施例の動作である。
　図３Ａの理想的な場合とは、明るさが十分な状態（例えば、被写体として近くの生体組織を撮像した場合）であって、かつノイズ低減処理によって画像信号に含まれるノイズがすべて除去される場合である。
　図３Ｂの比較例とは、被写体として遠くにある生体組織（暗い位置にある生体組織）を撮像した場合であって、ＡＧＣは行われるが、強度制御が行われない場合である。
　図３Ｃの実施例とは、図３Ｂと同様に、被写体として遠くにある生体組織（暗い位置にある生体組織）を撮像した場合である。図３Ｃの実施例は図３Ｂと異なり、上述した構成の電子内視鏡システム１によって処理がなされた場合、つまり、ＡＧＣが行われ、かつ強度制御が行われる場合である。 Next, the operation of the image processing section 22 in the electronic endoscope system 1 of this embodiment will be described with reference to FIGS. 3A to 3C. 3A shows the operation in the ideal case, FIG. 3B shows the operation in the comparative example, and FIG. 3C shows the operation in the example.
The ideal case of FIG. 3A is a state of sufficient brightness (for example, when imaging a nearby biological tissue as a subject), and all noise contained in the image signal is removed by noise reduction processing. is the case.
The comparative example in FIG. 3B is a case in which a distant biological tissue (a biological tissue in a dark position) is imaged as an object, and AGC is performed, but intensity control is not performed.
The example of FIG. 3C is a case of imaging a distant living tissue (a living tissue in a dark position) as a subject, as in FIG. 3B. The embodiment of FIG. 3C differs from that of FIG. 3B in that processing is performed by the electronic endoscope system 1 configured as described above, that is, AGC is performed and intensity control is performed.
　図３Ａ～図３Ｃのそれぞれにおいて、状態Ｓ１はＡＧＣが行われる前の画像信号の状態を示し、状態Ｓ２はＡＧＣが行われた後の画像信号の状態を示し、状態Ｓ３はノイズ低減処理が行われた後の画像信号の状態を示し、状態Ｓ４はエッジ強調処理が行われた後の画像信号の状態を示している。 In each of FIGS. 3A to 3C, state S1 indicates the state of the image signal before AGC is performed, state S2 indicates the state of the image signal after AGC is performed, and state S3 indicates the state of the image signal after noise reduction processing is performed. The state S4 shows the state of the image signal after edge enhancement processing.
　先ず、図３Ａを参照すると、明るさが十分な状態であるため、ＡＧＣが行われる前の状態Ｓ１の画像信号の信号レベルが比較的高い。画像信号にはノイズが重畳している。画像信号のレベルが比較的高いことからＡＧＣにおける増幅率が小さく設定される。例えば増幅率が１倍（等倍）であるとすると、ＡＧＣが行われた後の状態Ｓ２の画像信号の信号レベル及びノイズレベルは、状態Ｓ１と変化がない。 First, referring to FIG. 3A, since the brightness is sufficient, the signal level of the image signal in state S1 before AGC is performed is relatively high. Noise is superimposed on the image signal. Since the level of the image signal is relatively high, the amplification factor in AGC is set small. For example, if the amplification factor is 1 (same magnification), the signal level and noise level of the image signal in state S2 after AGC is performed are the same as in state S1.
　次いで、ノイズ低減処理が行われると、状態Ｓ３に示すように、画像信号に重畳していた高周波成分のノイズが除去される。最後に、状態Ｓ４においてエッジ強調処理を施すと、信号レベルの変化が急峻な部分が強調された画像信号が得られる。 Next, when noise reduction processing is performed, as shown in state S3, noise of high-frequency components superimposed on the image signal is removed. Finally, when edge enhancement processing is performed in state S4, an image signal is obtained in which portions where the signal level changes steeply are enhanced.
　次に、図３Ｂを参照すると、被写体として遠くにある生体組織（暗い位置にある生体組織）を撮像した場合であるため、ＡＧＣが行われる前の状態Ｓ１の画像信号の信号レベルは比較的低い。画像信号にはノイズが重畳しているが、ノイズのレベルは、明るさが十分である場合と同程度であるため、Ｓ／Ｎ比が低い状態となっている。画像信号のレベルが比較的低いことからＡＧＣにおける増幅率が大きく設定される。例えば増幅率が４倍であるとすると、ＡＧＣが行われた後の状態Ｓ２の画像信号の信号レベル及びノイズレベルは、いずれも状態Ｓ１と比較して４倍となる。 Next, referring to FIG. 3B, since a distant living tissue (a living tissue in a dark position) is imaged as an object, the signal level of the image signal in state S1 before AGC is performed is relatively low. . Although noise is superimposed on the image signal, the noise level is about the same as when the brightness is sufficient, so the S/N ratio is low. Since the level of the image signal is relatively low, the amplification factor in AGC is set large. For example, if the amplification factor is four times, the signal level and noise level of the image signal in state S2 after AGC is performed are both four times those in state S1.
　次いで、ノイズ低減処理が行われるが、状態Ｓ２においてノイズレベルが増幅されていることから、ノイズレベルが小さい図３Ａの場合と異なり、ノイズが十分に除去できない。そして、ノイズが含まれた状態の画像信号に対してエッジ強調処理を行うと、ノイズの部分に対してエッジ強調されるため、画像が劣化することになる。 Next, noise reduction processing is performed, but since the noise level is amplified in state S2, the noise cannot be sufficiently removed unlike the case of FIG. 3A where the noise level is low. When edge enhancement processing is performed on an image signal containing noise, the edge enhancement is applied to the noise portion, resulting in deterioration of the image.
　次に、図３Ｃを参照すると、状態Ｓ１から状態Ｓ３までは、図３Ｂと同じである。ここで、ＡＧＣにおける増幅率が大きいことから、増幅率のデータが入力された強度制御部２２６では、エッジ強調の程度を図３Ｂの場合と比較して低下させるように制御される。その結果、状態Ｓ４に示すように、除去されなかったノイズ部分でエッジ強調されることが抑制され、図３Ｂの場合と比較して画像のＳ／Ｎ比を改善することができる。 Next, referring to FIG. 3C, states S1 to S3 are the same as in FIG. 3B. Here, since the amplification factor in AGC is large, the intensity control unit 226 to which the data of the amplification factor is input controls the degree of edge enhancement to be lower than in the case of FIG. 3B. As a result, as shown in state S4, it is possible to suppress edge enhancement in noise portions that have not been removed, and to improve the S/N ratio of the image compared to the case of FIG. 3B.
　図３Ｃに示すように、本実施形態の電子内視鏡システム１では、暗い位置にある生体組織を撮像した場合に従来と比較して画像のＳ／Ｎ比を改善することができる。図３Ｃの場合、図３Ａの理想的な場合と比較すると十分な強調処理が得られないが、被写体に対して電子スコープ１００の先端を近付けた場合には、明るさが十分となりＡＧＣ部２２１にて設定される増幅率が低下するため、強度制御部２２６におけるエッジ強調の程度を低下させずに済むことから、図３Ａの場合と同様に、信号レベルの変化が急峻な部分が強調された画像信号を得ることができる。 As shown in FIG. 3C, the electronic endoscope system 1 of the present embodiment can improve the S/N ratio of the image compared to the conventional one when imaging a living tissue in a dark position. In the case of FIG. 3C, sufficient enhancement processing cannot be obtained as compared with the ideal case of FIG. Since the amplification factor set by the controller 226 is lowered, the degree of edge enhancement in the intensity control unit 226 does not need to be lowered. Therefore, as in the case of FIG. signal can be obtained.
　一実施形態では、図４に示すように、強度制御部２２６が、ＡＧＣ部２２１によって決定された増幅率に応じてノイズ成分の低減度合い（つまり、ノイズ低減処理の強度）が変更されるように、ノイズ低減処理部２２３を制御することも好ましい。
　例えば、図３に例示した場合、ＡＧＣによる増幅率を４倍にするとノイズも４倍になるため、画像信号に影響がない範囲内でノイズ低減の強度を上げるようにするとよい。ノイズ低減の強度を上げたことでノイズが低下した分、エッジ強調の強度を上げてもノイズが目立たなくなるため、エッジ強調処理の強度を上げる余地が生ずる。
　すなわち、ＡＧＣ部２２１における増幅率に応じて、ノイズ低減処理の強度とエッジ強調処理の強度とをバランス良く調整することで、後段処理部２２５に送る画像信号を最適なものにすることができる。 In one embodiment, as shown in FIG. 4, the intensity control unit 226 changes the degree of noise component reduction (that is, the intensity of noise reduction processing) according to the amplification factor determined by the AGC unit 221. , the noise reduction processing unit 223 is also preferably controlled.
For example, in the example shown in FIG. 3, if the amplification factor of AGC is quadrupled, the noise is also quadrupled. Therefore, it is preferable to increase the noise reduction strength within a range that does not affect the image signal. Since noise is reduced by increasing the strength of noise reduction, the noise becomes less conspicuous even if the strength of edge enhancement is increased, so there is room to increase the strength of edge enhancement processing.
That is, by adjusting the strength of noise reduction processing and the strength of edge enhancement processing in a well-balanced manner according to the amplification factor in AGC section 221, the image signal sent to post-processing section 225 can be optimized.
　以上、本発明の電子内視鏡用プロセッサ及び電子内視鏡システムについて詳細に説明したが、本発明の電子内視鏡用プロセッサ及び電子内視鏡システムは上記実施形態に限定されず、本発明の主旨を逸脱しない範囲において、種々の改良や変更をしてもよいのはもちろんである。 Although the electronic endoscope processor and electronic endoscope system of the present invention have been described in detail above, the electronic endoscope processor and electronic endoscope system of the present invention are not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments. Of course, various improvements and changes may be made without departing from the gist of the above.
　本発明は、２０２１年１１月１６日に日本国特許庁に出願された特願２０２１－１８６２０５の特許出願に関連しており、この出願のすべての内容がこの明細書に参照によって組み込まれる。 The present invention relates to the patent application of Japanese Patent Application No. 2021-186205 filed with the Japan Patent Office on November 16, 2021, and the entire contents of this application are incorporated herein by reference.

Claims (4)

  1. 　生体組織の撮像画像を取得して処理するように構成された電子内視鏡用プロセッサであって、
    　前記生体組織に対する照明光を出射する光源装置と、
    　前記撮像画像の明るさに関する情報に基づいて前記照明光の強度を制御する光源制御部と、
    　前記照明光の強度に基づいて利得を決定し、決定した前記利得によって前記撮像画像を増幅する自動利得制御部と、
    　前記自動利得制御部によって増幅された前記撮像画像に対してエッジ強調処理を行うエッジ強調処理部と、
    　前記自動利得制御部によって決定された利得が大きいほど前記エッジ強調処理の強調の程度が低下するように、前記エッジ強調処理部を制御する制御部と、
    　を備えた電子内視鏡用プロセッサ。     An electronic endoscope processor configured to acquire and process captured images of living tissue,
    a light source device that emits illumination light for the living tissue;
    a light source control unit that controls the intensity of the illumination light based on information about the brightness of the captured image;
    an automatic gain control unit that determines a gain based on the intensity of the illumination light and amplifies the captured image with the determined gain;
    an edge enhancement processing unit that performs edge enhancement processing on the captured image amplified by the automatic gain control unit;
    a control unit for controlling the edge enhancement processing unit such that the greater the gain determined by the automatic gain control unit, the lower the degree of enhancement of the edge enhancement processing;
    A processor for an electronic endoscope.
  2. 　前記自動利得制御部によって増幅された前記撮像画像に含まれるノイズ成分を低減するノイズ低減処理部を有し、
    　前記エッジ強調処理部は、前記ノイズ成分が低減された前記撮像画像に対して前記エッジ強調処理を行う、
    　請求項１に記載された電子内視鏡用プロセッサ。     a noise reduction processing unit that reduces noise components included in the captured image amplified by the automatic gain control unit;
    The edge enhancement processing unit performs the edge enhancement processing on the captured image in which the noise component has been reduced.
    The electronic endoscope processor according to claim 1.
  3. 　前記制御部は、前記自動利得制御部によって決定された利得に応じて前記ノイズ成分の低減度合いが変更されるように、前記ノイズ低減処理部を制御する、
    　請求項２に記載された電子内視鏡用プロセッサ。     The control unit controls the noise reduction processing unit such that the degree of reduction of the noise component is changed according to the gain determined by the automatic gain control unit.
    The electronic endoscope processor according to claim 2.
  4. 　請求項１～３のいずれか一項に記載の電子内視鏡用プロセッサと、
    　前記電子内視鏡用プロセッサに接続され、前記生体組織の撮像画像を取得する撮像素子を備えた電子内視鏡と、
    　を備える電子内視鏡システム。     an electronic endoscope processor according to any one of claims 1 to 3;
    an electronic endoscope that is connected to the electronic endoscope processor and that includes an imaging device that acquires a captured image of the biological tissue;
    An electronic endoscope system.
PCT/JP2022/039146 2021-11-16 2022-10-20 Processor for electronic endoscope and electronic endoscopic system WO2023090044A1 (en)

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Citations (5)

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Publication number Priority date Publication date Assignee Title
JPH0690900A (en) * 1992-06-16 1994-04-05 Olympus Optical Co Ltd Electronic endoscope apparatus
JP2001008097A (en) * 1999-06-22 2001-01-12 Fuji Photo Optical Co Ltd Electronic endoscope
JP2009219719A (en) * 2008-03-18 2009-10-01 Fujifilm Corp Endoscope system
JP2014097124A (en) * 2012-11-13 2014-05-29 Olympus Medical Systems Corp Imaging system
WO2016151903A1 (en) * 2015-03-25 2016-09-29 オリンパス株式会社 Observation system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0690900A (en) * 1992-06-16 1994-04-05 Olympus Optical Co Ltd Electronic endoscope apparatus
JP2001008097A (en) * 1999-06-22 2001-01-12 Fuji Photo Optical Co Ltd Electronic endoscope
JP2009219719A (en) * 2008-03-18 2009-10-01 Fujifilm Corp Endoscope system
JP2014097124A (en) * 2012-11-13 2014-05-29 Olympus Medical Systems Corp Imaging system
WO2016151903A1 (en) * 2015-03-25 2016-09-29 オリンパス株式会社 Observation system

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