JP2012254240A - Image signal processing device and electronic endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image signal processing device suited for observing an image with insufficient luminance, such as a narrow-band optical image and a fluorescence image.SOLUTION: This image signal processing device includes: an image signal input means that receives an image signal from an image pickup apparatus that has imaged a subject irradiated with light with a specific wavelength having a wavelength band narrower than that of predetermined broadband light; a branching means for branching an output of the input image signal into a plurality of outputs; a gain amplification means for performing different gain amplification to the output of each branched image signal; a composite image generating means for synthesizing each image signal subjected to the different gain amplification and generating a composite image by arranging images corresponding to the image signals in the same screen.

Description

  The present invention relates to an image signal processing apparatus that processes an image signal so that it can be displayed on a monitor. More specifically, the present invention relates to an image signal processing apparatus that displays the same subject as a plurality of images having different luminances in one screen. The present invention also relates to an electronic endoscope system having the image signal processing device.

  In the medical device field, there is known an electronic endoscope system that generates and displays an enhanced image (narrowband light image or fluorescent image) of a specific part in a body cavity by irradiating the body cavity with narrowband light or excitation light. ing. A specific configuration example of this type of electronic endoscope system is described in Patent Document 1. Patent Document 1 describes a configuration in which images of two different observation modes such as narrow-band light observation and fluorescence observation are displayed side by side in order to support diagnosis by an operator through an endoscopic image. .

JP 2007-20727 A

  In order to generate a narrow-band light image, it is necessary to limit the wavelength of irradiation light. Moreover, in order to generate a fluorescence image, it is necessary to use light (excitation light) having a specific wavelength as a light source. As described above, in the narrow-band light observation and the fluorescence observation, the wavelength to be used is limited, so that the amount of light applied to the subject is small compared to the normal endoscopic observation using the white light that is the broadband light. Therefore, the narrow-band light image and the fluorescence image have a problem that they are dark and difficult to observe.

  Insufficient brightness in narrowband light images and fluorescent images can be resolved by increasing the gain. However, in this case, noise increases with gain and the image quality deteriorates, so there is a risk that the subject (particularly details) will be difficult to observe.

  An image signal processing apparatus according to an embodiment of the present invention that solves the above-described problems inputs an image signal from an imaging apparatus that captures a subject irradiated with light having a specific wavelength that is narrower than a predetermined broadband light. Image signal input means, branch means for branching the output of the input image signal into a plurality, gain amplifying means for performing different gain amplification on the output of each branched image signal, and each image subjected to different gain amplification The image processing apparatus includes a composite image generation unit configured to generate a composite image in which signals corresponding to each image signal are combined and arranged in one screen.

  According to the image signal processing apparatus of the present invention, it is suitable for examining a fine structure of a living body having a low brightness and a narrow-band light image (an image having a large gain amplification) that is easy to visually recognize around the subject. In addition, the same subject is displayed as a plurality of images with different luminances in one screen, such as a narrow band light image (an image with no gain amplification or a small image). The surgeon can examine the details of the subject through the latter image with little deterioration in image quality while observing the surroundings of the subject through the former image in which the lack of luminance is resolved.

  The branching unit may branch the input image signal into two outputs. In this case, for example, the gain amplifying means increases the gain for one of the branched signal outputs, and does not perform the gain amplification for the other signal output.

  The synthesized image generating means displays the first image corresponding to the signal output with the gain increased as a sub-screen of the second image corresponding to the signal output not subjected to gain amplification by the gain amplifying means. It is good also as a structure which produces | generates a synthesized image.

  The gain amplifying unit may be configured to perform gain amplification so that the luminance of a specific region in the first image corresponding to the signal output with the gain increased is higher than the luminance of a region other than the specific region.

  The composite image generation means is a composite image in which a plurality of images corresponding to each image signal are arranged side by side in a predetermined direction in one screen, or a composition in which each of the plurality of images partially overlaps each other. It is good also as a structure which produces | generates an image.

  An electronic endoscope system according to an aspect of the present invention that solves the above problem includes a light irradiation unit that irradiates light having a specific wavelength narrower than a predetermined broadband light, and reflected light from the irradiated subject. Imaging means for receiving light and converting it to a signal, image signal generating means for processing the converted signal to generate an image signal, branching means for branching the output of the generated image signal into a plurality, and each branching A composite image in which gain amplification means for performing different gain amplification on the output of the image signal and images corresponding to the different gain amplification are combined and images corresponding to the image signals are arranged in one screen. And a synthesized image generating means for generating the system.

  The light irradiating means may include a light source that emits broadband light and a narrow band filter that is detachably arranged with respect to the optical path and limits the broadband light to light of a specific wavelength. The light irradiating means irradiates the subject with broadband light when the narrow band filter is retracted from the optical path, and irradiates the subject with narrow band light when the narrow band filter is inserted in the optical path.

  ADVANTAGE OF THE INVENTION According to this invention, the image signal processing apparatus and electronic endoscope system suitable for observing an image with insufficient brightness | luminance, such as a narrow-band light image and a fluorescence image, are provided. That is, the image signal processing apparatus according to the present invention displays the same subject as a plurality of images having different luminances in one screen. Specifically, in order to avoid the deterioration of image quality due to excessive gain amplification and lack of light intensity (due to insufficient brightness), it will cause troubles in diagnosis, so there will be less noise and the fine structure of the living body will be scrutinized. A narrow-band light image (image with no gain amplification or a small image) suitable for the image and a narrow-band light image (image with large gain amplification) that has high brightness and is easy to see around the subject. it can.

It is a block diagram which shows the structure of the electronic endoscope system which concerns on embodiment of this invention. It is a figure which shows the flowchart of the normal color image observation process which concerns on embodiment of this invention. It is a figure which shows the flowchart of the narrow-band optical image observation process which concerns on embodiment of this invention. It is a figure which shows the example of a display screen of a monitor when observation mode is set to narrow band light observation mode.

  Hereinafter, an electronic endoscope system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of an electronic endoscope system 1 according to the present embodiment. As shown in FIG. 1, the electronic endoscope system 1 is a medical imaging system, and includes an electronic scope 100, a processor 200, and a monitor 300. The proximal end of the electronic scope 100 is connected to the processor 200. The processor 200 integrally includes an image signal processing device that processes an image signal output from the electronic scope 100 to generate an image, and a light source device that illuminates a body cavity that does not reach natural light via the electronic scope 100. It is. In another embodiment, the image signal processing device and the light source device may be configured separately.

  As illustrated in FIG. 1, the processor 200 includes a system controller 202 and a timing controller 204. The system controller 202 controls each element constituting the electronic endoscope system 1. The timing controller 204 outputs a clock pulse for adjusting the signal processing timing to each circuit in the electronic endoscope system 1.

  The lamp 208 radiates light in a wavelength range mainly extending from the visible light region to the invisible infrared region after being started by the lamp power igniter 206. As the lamp 208, a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, or a metal halide lamp is suitable. The illumination light emitted from the lamp 208 is condensed by the condenser lens 210 and is limited to an appropriate amount of light through the diaphragm 212.

  A motor 214 is mechanically connected to the diaphragm 212 via a transmission mechanism such as an arm or a gear (not shown). The motor 214 is a DC motor, for example, and is driven under the drive control of the driver 216. The diaphragm 212 is operated by the motor 214 to change the opening degree so that the image displayed on the monitor 300 has an appropriate brightness, and the amount of illumination light emitted from the lamp 208 is limited according to the opening degree. To do. The appropriate reference for the brightness of the image is changed according to the brightness adjustment operation performed by the operator on the front panel 218 or the hand operation unit (not shown) of the electronic scope 100. Note that the dimming circuit that controls the brightness by controlling the driver 216 is a well-known circuit and is omitted in this specification.

  Various forms of the configuration of the front panel 218 are assumed. As a specific configuration example of the front panel 218, a hardware key for each function mounted on the front surface of the processor 200, a touch panel GUI (Graphical User Interface), a combination of a hardware key and a GUI, and the like are assumed. .

  The irradiation light that has passed through the diaphragm 212 is split into specific narrow-band light (for example, light with a narrow half-value width having a transmission peak in a wavelength range suitable for absorption of hemoglobin) by an optical filter 213, and LCB (Light Carrying Bundle) The light enters the incident end 102. A motor 215 driven under the drive control of the driver 216 is mechanically coupled to the optical filter 213 via a transmission mechanism such as an arm or a gear (not shown). The motor 215 inserts the optical filter 213 into the optical path or retracts it from the optical path in accordance with the switching operation on the front panel 218 by the operator or the operation of the switching button 114 provided on the hand operation unit of the electronic scope 100. In FIG. 1, the connection between the switching button 114 (and a freeze button 116 described later) and other blocks is omitted to simplify the drawing. During the period in which the optical filter 213 is retracted from the optical path, the irradiation light that has passed through the diaphragm 212 (that is, broadband light including the visible light region) is directly incident on the incident end of the LCB 102. As the motors 214 and 215, for example, a galvano motor or a servo motor is assumed.

  Irradiation light incident on the incident end of the LCB 102 propagates by repeating total reflection in the LCB 102. Irradiation light propagating through the LCB 102 is emitted from the emission end of the LCB 102 disposed at the tip of the electronic scope 100. Irradiation light emitted from the exit end of the LCB 102 irradiates the subject via the light distribution lens 104. The reflected light from the subject forms an optical image at each pixel on the light receiving surface of the solid-state image sensor 108 via the objective lens 106.

  The solid-state imaging device 108 is, for example, a single-plate color CCD (Charge Coupled Device) image sensor having a Bayer-type pixel arrangement, accumulates an optical image formed by each pixel on the light receiving surface as a charge corresponding to the amount of light, The image signal is converted into an image signal corresponding to each color of R, G, and B. The converted image signal is amplified by the preamplifier 110 and then input to the endoscope side signal processing circuit 112. In another embodiment, the solid-state image sensor 108 may be a complementary metal oxide semiconductor (CMOS) image sensor.

  The timing controller 204 supplies clock pulses to the endoscope side signal processing circuit 112 according to the timing control by the system controller 202. The endoscope side signal processing circuit 112 controls driving of the solid-state imaging device 108 at a timing synchronized with a frame rate of a video processed on the processor 200 side, according to a clock pulse supplied from the timing controller 204.

  The image signal input to the endoscope side signal processing circuit 112 is subjected to processor side signal processing after processing of reset noise and amplifier noise by correlated double sampling processing, gain adjustment by AGC (Auto Gain Control), AD conversion, and the like. Input to the circuit 220.

  The digital signal sequence input to the processor-side signal processing circuit 220 is buffered in units of frames in the first frame memory 220a. The buffered digital signal sequence is branched and output from the first frame memory 220a into two systems at a timing controlled by the timing controller 204. One output is input to the synthesis circuit 220d via the gain amplification circuit 220b and the second frame memory 220c. The other output is directly input to the synthesis circuit 220d. For convenience of explanation, a digital signal sequence input to the combining circuit 220d via the gain amplification circuit 220b and the second frame memory 220c after outputting the first frame memory 220a is referred to as a “gain amplification signal sequence”, and the gain amplification circuit 220b, A digital signal sequence that is directly input to the synthesis circuit 220d without passing through the second frame memory 220c is referred to as a “gain normal signal sequence”.

  Unlike the preamplifier 110 that amplifies a weak analog signal output from the solid-state image sensor 108 and the AGC that adjusts the gain to an appropriate level, the gain amplification circuit 220b does not take image quality degradation due to noise into consideration. The gain amplification is performed mainly for the purpose of improving the visibility by increasing. The second frame memory 220c normally outputs the input from the gain amplifying circuit 220b.

  The combining circuit 220d converts the input digital signal sequence into a video signal that conforms to a predetermined standard such as NTSC (National Television System Committee) or PAL (Phase Alternating Line). By sequentially inputting the converted video signals to the monitor 300, the image of the subject is displayed on the display screen of the monitor 300.

  An image of the subject is displayed on the display screen of the monitor 300 in a form corresponding to the observation mode. The observation mode is set and changed according to an observation mode setting operation performed by the operator on the front panel 218 or the hand operation unit of the electronic scope 100.

(Normal color image observation processing)
FIG. 2 is a flowchart of normal color image observation processing according to the embodiment of the present invention. The normal color image observation process is executed when the observation mode is set to the normal observation mode. Execution of the normal color image observation process continues until switching to another observation mode other than the normal observation mode or until the power of the processor 200 is turned off. For convenience of explanation, the processing step is abbreviated as “S” in the description and drawings in this specification.

<S1 in FIG. 2 (Optical Filter Retraction Process)>
The motor 215 retracts the optical filter 213 from the optical path between the stop 212 and the incident end of the LCB 102 according to drive control by the driver 216. For this reason, the subject is irradiated with broadband light including a visible light region. The solid-state image sensor 108 receives reflected light from a subject irradiated with broadband light and converts it into an image signal. The image signal is converted into a gain amplification signal sequence and a gain normal signal sequence through processing of each circuit of the preamplifier 110, the endoscope side signal processing circuit 112, the first frame memory 220a, and the gain amplification circuit 220b.

<S2 in FIG. 2 (Image Output Processing)>
The synthesizing circuit 220d cuts off the input of the gain amplification signal string and performs conversion processing into a video signal using only the gain normal signal string. As a result, a color image (moving image) of a subject that has not been gain-amplified by the gain amplification circuit 220b is displayed in a predetermined area (a display area reserved for displaying an endoscopic image) in the display screen of the monitor 300. .

  When the freeze button 116 is pressed, the digital signal sequence in the first frame memory 220a is fixed to a signal sequence corresponding to the frame immediately after the button operation for a predetermined period (for example, several seconds). Thereby, the input to the synthesis circuit 220d is fixed. For a few seconds when the input to the combining circuit 220d is fixed, a color image (still image) of a subject that has not been gain-amplified by the gain-amplifying circuit 220b is displayed in a predetermined area in the display screen of the monitor 300. The

(Narrowband optical image observation processing)
FIG. 3 shows a flowchart of the narrow-band light image observation process according to the embodiment of the present invention. The narrowband light image observation process of the present embodiment is executed when the observation mode is set to the narrowband light observation mode. The execution of the narrowband light image observation process is continued until the observation mode is switched to another observation mode other than the narrowband light observation mode or the power of the processor 200 is turned off. 4A to 4C are diagrams showing examples of display screens of the monitor 300 when the observation mode is set to the narrow-band light observation mode. For convenience of explanation, an image constituted by a gain amplified signal sequence is referred to as “gain amplified image”, and an image constituted by a gain normal signal sequence is referred to as “gain normal image”.

<S11 in FIG. 3 (Optical Filter Insertion Processing)>
The motor 215 inserts the optical filter 213 into the optical path between the stop 212 and the incident end of the LCB 102 according to drive control by the driver 216. Therefore, the subject is irradiated with specific narrowband light. The solid-state image sensor 108 receives the reflected light from the subject irradiated with the narrow-band light and converts it into an image signal. The image signal is converted into a gain amplification signal sequence and a gain normal signal sequence through processing of each circuit of the preamplifier 110, the endoscope side signal processing circuit 112, the first frame memory 220a, and the gain amplification circuit 220b.

<S12 in FIG. 3 (Image Output Processing)>
The combining circuit 220d performs a conversion process to a video signal after combining the gain-amplified image and the gain normal image into a single image. Thereby, an endoscopic observation image obtained by synthesizing the gain-amplified image (moving image) and the gain normal image (moving image) is displayed in a predetermined area in the display screen of the monitor 300. In the present embodiment, the gain normal image is the main screen (parent screen) and the gain-amplified image is the sub-screen (child screen). The composite image is obtained by superimposing a gain-amplified image (moving image), which is a sub-screen, on the upper right area of a gain normal image (moving image) that is displayed largely as a main screen (see FIG. 4A).

  According to the display screen example in FIG. 4A, a narrow-band light image (gain normal image) with less noise and the sameness (observation field of view and shooting time is the same) and a narrow-band light image (gain-amplified image) with high brightness. ) Are displayed simultaneously on one screen. Since the normal gain image has less noise, it is suitable for examining the fine structure of the living body. Since the gain-amplified image has high brightness and allows the periphery of the subject to be easily viewed, it is suitable for allowing the operator to grasp the current observation position of the electronic scope 100 and the direction to be inserted. The surgeon can discover or diagnose a lesioned part or the like by comparing and observing two images within one screen having the same identity except for the luminance.

  Note that the layout of the gain normal image and the gain amplified image can be changed according to the layout switching operation performed by the operator on the front panel 218 or the hand operation unit of the electronic scope 100. FIG. 4C shows an example of a screen display of a gain normal image and a gain amplified image after layout switching. In the screen display example of FIG. 4C, the gain normal image and the gain amplified image are arranged in the same display size and aligned in the long side direction (horizontal direction) of the display screen of the monitor 300 in one screen.

  The gain-amplified image may be gain-amplified so that the luminance of a specific area in the image is higher than the luminance of other areas. The gain amplifying circuit 220b generally amplifies the gain of the central region of the gain-amplified image so that the luminance is higher than that of the peripheral region because the subject is generally arranged at the center of the observation field. It is possible to designate which region to increase the luminance through the operator's operation on the front panel 218 or the hand operation unit of the electronic scope 100.

<S13 in FIG. 3 (Freeze Operation Determination Process)>
When the freeze button 116 is pressed (S13: YES), the second frame memory 220c takes in a digital signal sequence for one frame immediately after the button operation and fixes it for a predetermined period (for example, several seconds). When the freeze button 116 is not pressed (S13: NO), the second frame memory 220c continues to output the input from the gain amplification circuit 220b as usual.

<S14 in FIG. 3 (Image Output Processing)>
By fixing the digital signal sequence by the second frame memory 220c, the input (gain amplification signal sequence) to the synthesis circuit 220d via the gain amplification circuit 220b and the second frame memory 220c is fixed. On the other hand, the direct input (gain normal signal sequence) from the first frame memory 220a to the synthesis circuit 220d is not fixed. For a few seconds when the former input is fixed, an endoscopic observation image obtained by synthesizing a gain-amplified image (still image) and a gain normal image (moving image) is displayed in a predetermined area in the display screen of the monitor 300. (See FIG. 4 (b)).

<S15 in FIG. 3 (Freeze Release Processing)>
After a predetermined period of time has passed since the freeze button 116 was pressed (S15: YES), the second frame memory 220c releases the fixation of the digital signal sequence and outputs the input from the gain amplification circuit 220b as a through output. As a result, both the gain-amplified image and the gain normal image become moving images (see FIG. 4A).

  Still images lack brightness compared to movies. If a narrow-band light image with insufficient brightness is a still image, it is difficult to see the surroundings of the subject because the brightness is insufficient, and the current observation position of the electronic scope 100 and the direction to be inserted can be determined. It was difficult for the person to grasp. However, the gain-amplified image (still image) is suitable for causing the surgeon to grasp the current observation position of the electronic scope 100 and the direction in which the electronic scope 100 should be inserted because the luminance deficiency has been resolved by gain amplification.

  The above is the description of the embodiment of the present invention. The present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the technical idea of the present invention. For example, in this embodiment, a narrowband light image is displayed, but in another embodiment, a fluorescent image may be displayed instead of the narrowband light image.

  In the present embodiment, two narrow-band light images with different luminances are displayed on one screen. However, in another embodiment, three or more narrow-band light images with different luminances may be displayed on one screen. . For example, a configuration may be adopted in which three types of images are displayed on one screen by adding an image that has been gain-amplified so that the luminance is intermediate between the gain-amplified image and the gain normal image.

  In the present embodiment, the gain normal image and the gain amplified image are the main screen and the sub screen, respectively, but in another embodiment, the gain normal image may be the sub screen and the gain amplified image may be the main screen.

DESCRIPTION OF SYMBOLS 1 Electronic endoscope system 100 Electronic scope 200 Processor 220 Processor side signal processing circuit 220a First frame memory 220b Gain amplification circuit 220c Second frame memory 220d Synthesis circuit 300 Monitor

Claims (7)

An image signal input means for inputting an image signal from an imaging device that has photographed a subject irradiated with light of a specific wavelength whose wavelength range is narrower than a predetermined broadband light;
Branching means for branching the output of the input image signal into a plurality of;
Gain amplifying means for performing different gain amplification on the output of each of the branched image signals;
Combined image generating means for combining the image signals subjected to different gain amplification and generating a combined image in which images corresponding to the image signals are arranged side by side in one screen;
An image signal processing apparatus comprising: The branching unit branches the input image signal into two outputs,
2. The image signal processing apparatus according to claim 1, wherein the gain amplifying unit increases the gain for one of the branched signal outputs and does not perform gain amplification for the other signal output.   In the composite image generation means, a first image corresponding to the signal output with the gain increased is displayed as a sub-screen of a second image corresponding to a signal output not subjected to gain amplification by the gain amplification means. The image signal processing apparatus according to claim 2, wherein the composite image is generated as described above.   The gain amplifying means performs gain amplification so that the brightness of a specific area in the first image corresponding to the signal output with the gain increased is higher than the brightness of an area other than the specific area. The image signal processing device according to claim 2 or 3.   The composite image generation means is a composite image in which a plurality of images corresponding to the image signals are arranged in a predetermined direction in the screen, or each of the plurality of images partially overlaps each other. 5. The image signal processing apparatus according to claim 1, wherein a composite image to be arranged is generated. 6. Light irradiating means for irradiating light of a specific wavelength whose wavelength range is narrower than a predetermined broadband light;
Imaging means for receiving reflected light from the irradiated subject and converting it into a signal;
Image signal generating means for processing the converted signal to generate an image signal;
Branching means for branching the output of the generated image signal into a plurality;
Gain amplifying means for performing different gain amplification on the output of each of the branched image signals;
Combined image generating means for combining the image signals subjected to different gain amplification and generating a combined image in which images corresponding to the image signals are arranged side by side in one screen;
An electronic endoscope system comprising: The light irradiation means includes
A light source for irradiating the broadband light;
A narrowband filter that is detachably disposed with respect to the optical path and restricts the broadband light to light of the specific wavelength;
Have
Irradiating the subject with the broadband light when the narrowband filter is retracted from the optical path, and irradiating the subject with the narrowband light when the narrowband filter is inserted on the optical path, The electronic endoscope system according to claim 6.

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