JP6370604B2 - Endoscope system - Google Patents

Description

  The present invention relates to an image processing apparatus and an endoscope system capable of switching matrix coefficients applied to color conversion processing.

  An endoscope system for observing the inside of a lumen such as a human esophagus or intestine is known. This type of endoscope system includes an endoscope processor that processes a pixel signal of each pixel of a subject imaged by an electronic scope to generate a video signal. There is also known an endoscope system that can switch the wavelength characteristics of illumination light that illuminates a subject so that an operator can easily view an observation image of a specific living tissue in a lumen.

  For example, Patent Document 1 describes an endoscope system capable of switching the wavelength characteristics of illumination light. The endoscope system described in Patent Document 1 includes a light source that emits illumination light in a wide wavelength band and a plurality of optical filters that limit the wavelength band of the illumination light. When the operator performs a filter switching operation on the endoscope system, the applied optical filter is switched. When the optical filter is switched, the matrix coefficient applied to the color conversion processing of the video signal is also switched. By using such an endoscope system, a matrix coefficient suitable for an optical filter is used for color conversion processing, and an observation image that is easy for the operator to view is obtained.

JP 2013-13589 A

  However, in the endoscope system described in Patent Document 1, when the operator performs a filter switching operation, the matrix coefficient is also switched immediately according to the switching operation. For this reason, for example, the matrix coefficient may be switched while the endoscope processor is performing color conversion processing on one image. In this case, it is pointed out that when different matrix coefficients are applied, regions of different colors are mixed in the image and the observation video is temporarily disturbed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image processing device that does not cause disturbance of an observed image due to switching of matrix coefficients regardless of the timing of instruction input by a user. An endoscope system is provided.

  A video processing apparatus according to an embodiment of the present invention that solves the above-described problem is a color conversion unit that sequentially performs color conversion processing based on a matrix coefficient on video signals sequentially input from a predetermined imaging device at a predetermined cycle; Input receiving means for receiving an instruction input from a user, and matrix coefficient switching means for switching a matrix coefficient used in the color conversion means to a matrix coefficient corresponding to the instruction input at a timing synchronized with the cycle of the video signal.

  According to such a configuration, the matrix coefficient is not switched during the color conversion process for one image, but is switched at a timing synchronized with the cycle of the video signal. For this reason, the application of different matrix coefficients does not cause a problem in that regions having different colors are mixed in the image and the observed video is temporarily disturbed.

  The matrix coefficient switching means may receive the synchronization signal synchronized with the cycle of the video signal from the imaging device, and may switch the matrix coefficient at the timing of receiving the synchronization signal after the input receiving means receives the instruction input.

  Further, the synchronization signal may be a vertical synchronization signal of a video signal. In this case, the matrix coefficient switching means switches the matrix coefficient used in the color conversion means to the matrix coefficient corresponding to the instruction input when the falling edge of the vertical synchronizing signal is detected after the input receiving means receives the instruction input. .

  The video processing apparatus may further include matrix coefficient storage means for storing a plurality of types of matrix coefficients. In this case, when the input receiving unit receives the instruction input, the matrix coefficient switching unit reads out the matrix coefficient corresponding to the instruction input from the matrix coefficient storage unit and uses it in the color conversion unit at a timing synchronized with the cycle of the video signal. The matrix coefficient to be read is switched to the matrix coefficient read from the matrix coefficient storage means.

  In addition, the video processing apparatus includes any one of a light source that emits illumination light that illuminates a subject, a plurality of types of filters that change the wavelength characteristics of the illumination light to different wavelength characteristics, and a plurality of types of filters based on an instruction input. Filter selection means for selecting one and filter arrangement means for arranging the selected filter in the optical path of the illumination light may be further provided. In this case, the matrix coefficient switching means switches the matrix coefficient used by the color conversion means to a matrix coefficient corresponding to the filter selected by the filter selection means at a timing synchronized with the cycle of the video signal.

  An endoscope system according to an embodiment of the present invention includes the above-described video processing device and an electronic scope including an imaging device that generates a video signal at a predetermined cycle and sequentially outputs the video signal.

  According to the embodiment of the present invention, there are provided an image processing apparatus and an endoscope system that do not cause disturbance of an observation image due to switching of matrix coefficients regardless of timing of instruction input by a user.

It is a block diagram which shows the structure of the endoscope system concerning embodiment of this invention. It is a front view of the filter turret concerning the embodiment of the present invention. It is a figure which shows the spectral characteristics of the optical filter concerning embodiment of this invention. It is the figure which represented typically a part of light-receiving surface of the image pick-up element concerning embodiment of this invention. It is a block diagram which shows the structure of the color conversion circuit concerning embodiment of this invention. 5 is a timing chart showing operation timings of the color conversion circuit according to the embodiment of the present invention.

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

  FIG. 1 is a block diagram showing a configuration of an endoscope system 1 of the present embodiment. As shown in FIG. 1, the endoscope system 1 is a medical imaging system, and includes an electronic scope 100, a processor 200, and a monitor 300.

  The electronic scope 100 includes an illumination optical system 101, an objective optical system 102, an image sensor 103, an AFE (Analog Front End) 104, a light guide 105, an electrical connector 106, and an electrical connector 107.

  The processor 200 includes a system controller 201, a timing controller 202, a light source driver 203, a light source 204, a condenser lens 205, a filter turret 206, a motor driver 207, a motor 208, a photo interrupter 209, a signal processing circuit 210, a video signal generation circuit 211, and the like. A front panel 212 is provided. The signal processing circuit 210 includes a demosaic processing circuit 210A, a color conversion circuit 210B, a color correction circuit 210C, and a noise removal circuit 210D.

  The system controller 201 controls each element constituting the endoscope system 1. The timing controller 202 transmits a clock pulse for adjusting a signal processing timing to each circuit in the endoscope system 1. The system controller 201 is connected to the front panel 212. The front panel 212 is a user interface for the operator to change various settings and various parameters of the endoscope system 1. The system controller 201 controls each element based on an input operation to the front panel 212 by the operator.

  The light source 204 is driven and controlled by the light source driver 203 to emit white light. As the light source 204, a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, or a metal halide lamp is used. The illumination light emitted from the light source 204 is incident on the light guide 105 via the condenser lens 205 and the filter turret 206.

  FIG. 2 shows a front view of the filter turret 206 viewed from the light source 204 side. The filter turret 206 has a disk shape. As shown in FIG. 2, the filter turret 206 includes a first optical filter 206 a and a second optical filter 206 b having different spectral characteristics arranged side by side in the circumferential direction. The filter turret 206 is rotated by a motor 208, whereby one of the first optical filter 206a and the second optical filter 206b is placed in the optical path of the illumination light (see a region L indicated by a dotted line in FIG. 2). One of two types of illumination light that is arranged and has different wavelength characteristics is taken out.

  FIG. 3 shows spectral characteristics of the first optical filter 206a and the second optical filter 206b. The horizontal axis in FIG. 3 indicates the wavelength (unit: nm), and the vertical axis indicates the transmittance (unit:%). As shown in FIG. 3, the transmittance Ta of the first optical filter 206a is almost 100% with respect to light in the visible light band having a wavelength of about 400 nm to about 700 nm. Therefore, the illumination light transmitted through the first optical filter 206a becomes white light. On the other hand, the second optical filter 206b has a high transmittance Tb with respect to light having a wavelength near 450 nm (blue light) and light near 550 nm (green light), and low transmittance Tb with respect to light having other wavelengths. Therefore, the light transmitted through the second optical filter 206b becomes a cyan color in which blue light and green light are mixed. Hereinafter, for convenience of explanation, the illumination light transmitted through the first optical filter 206a is referred to as “normal light”, and the illumination light transmitted through the second optical filter 206b is referred to as “narrow band light”.

  When the operator performs a filter switching operation on the front panel 212, the filter turret 206 rotates, and an optical filter corresponding to the filter switching operation is arranged in the optical path of the illumination light. Thereby, the illumination light (normal light or narrow band light) taken out by the filter turret 206 is switched. The rotational position and phase of rotation of the filter turret 206 are controlled by detecting an opening (not shown) formed in the vicinity of the outer periphery of the filter turret 206 by the photo interrupter 209.

  Illumination light (normal light or narrow-band light) that has passed through the filter turret 206 enters the light guide 105 and is guided in the light guide 105 toward the distal end portion of the electronic scope 100. The illumination light guided in the light guide 105 is emitted from the end surface of the light guide 105 disposed in the distal end portion of the electronic scope 100. Illumination light emitted from the end face of the light guide 105 is emitted from the electronic scope 100 via the illumination optical system 101 and illuminates the subject. Illumination light (reflected light) reflected by the subject enters the image sensor 103 via the objective optical system 102 and forms a subject image on the light receiving surface of each pixel included in the image sensor 103.

FIG. 4 schematically shows a part of the light receiving surface of the image sensor 103. The image sensor 103 is an interlaced single-plate color CCD (Charge Coupled Device) image sensor having a complementary color checkered pixel arrangement. In FIG. 4, “Ye”, “Cy”, “Mg”, and “G” indicate pixels having yellow (Ye), cyan (Cy), magenta (Mg), and green (G) color filters, respectively. Yes. Each pixel accumulates the formed subject image as a charge corresponding to the amount of light. The accumulated electric charges are read out based on the well-known color difference line sequential interlacing method. Specifically, a mixed signal obtained by adding pixel signals of two pixels adjacent in the vertical direction is sequentially read out. For example, in the example illustrated in FIG. 4, among the pixels of the image sensor 103, the mixed signal (Wr _in ) of the pixel signal of the Ye pixel of the n horizontal scanning lines and the pixel signal of the Mg pixel adjacent to the Ye pixel, and the Cy pixel And the mixed signal (Gb _in ) of the pixel signals of the G pixels adjacent to the Cy pixel are alternately read out. Next, (n + 1) the pixel signal of the pixel Y and the pixel signal of the pixel G of the pixel adjacent to the pixel Y (Gr _in ) of the horizontal scanning line, the pixel signal of the pixel Cy, and the pixel of the pixel Mg The mixed signal (Wb _in ) of the signals is alternately read out. In this way, the pixel signals for one field are read by sequentially reading the mixed signals of the horizontal scanning lines.

The AFE 104 performs signal amplification processing and A / D conversion processing on each mixed signal (Wr _in , Gb _in , Gr _in , Wb _in ) read from the image sensor 103, and outputs the obtained digital RAW data To do. Digital RAW data output from the AFE 104 is transmitted to the signal processing circuit 210 via the electrical connector 107. The demosaic processing circuit 210A performs well-known demosaic processing on the digital RAW data received from the AFE 104 to generate video data. The generated video data is transmitted to the color conversion circuit 210B.

The color conversion circuit 210B performs color conversion processing on the video data received from the demosaic processing circuit 210A. In the color conversion processing, each mixed signal (Wr _in , Gb _in , Gr _in , Wb _in ) included in the video data is subjected to matrix calculation processing represented by the following expression, and red (R), green (G) , Blue (B) image signals (R _out , G _out , B _out ) corresponding to the respective colors are generated.

  In the above formula, M represents a matrix coefficient. The color conversion circuit 210B holds a matrix coefficient M corresponding to each illumination light. When the illumination light that illuminates the subject is switched according to the filter switching operation on the front panel 212 by the surgeon, the color and contrast of the subject image change. Therefore, the color conversion circuit 210B switches the matrix coefficient M applied to the matrix calculation process to the matrix coefficient M corresponding to the illumination light after switching.

  The color correction circuit 210C performs color correction processing such as white balance adjustment processing and gamma correction processing on the video data on which the matrix calculation processing has been performed, and transmits the video data to the noise removal circuit 210D. The noise removal circuit 210D performs noise removal processing such as well-known spatial filter processing on the video data received from the color correction circuit 210C and transmits the processed video data to the video signal generation circuit 211.

  The video signal generation circuit 211 converts the video data received from the signal processing circuit 210 (noise removal circuit 210D) into a video signal of a predetermined format (for example, NTSC format) and transmits the video signal to the monitor 300. The monitor 300 displays an observation image of the subject based on the video signal received from the video signal generation circuit 211.

  Next, switching of matrix coefficients applied to video data will be described in detail. FIG. 5 is a block diagram showing the configuration of the color conversion circuit 210B. The color conversion circuit 210B includes a calculation unit 210B1 and a coefficient switching unit 210B2. The calculation unit 210B applies color conversion processing by applying matrix coefficients to the video data. The coefficient switching unit 210B2 switches matrix coefficients applied to the video data by the calculation unit 210B1.

  In a predetermined storage area of the coefficient switching unit 210B2, a matrix coefficient M1 that is applied when the illumination light is normal light and a matrix coefficient M2 that is applied when the illumination light is narrowband light are stored in advance. . When the operator performs a filter switching operation on the front panel 212, a filter switching signal indicating an optical filter to be used is transmitted to the selection unit SEL. The selection unit SEL reads the matrix coefficient (M1 or M2) according to the filter switching signal and transmits it to the output controller CTRL. The output controller CTRL transmits the matrix coefficient received from the selection unit SEL to the calculation unit 210B1 at a predetermined timing. When the calculation unit 210B1 receives the matrix coefficient from the selection unit SEL, the calculation unit 210B1 performs matrix calculation processing using the received matrix coefficient.

  The timing at which the output controller CTRL transmits the matrix coefficient is synchronized with the vertical synchronization signal included in the video data. Specifically, the vertical synchronization signal is transmitted every time a mixed signal for one field is read from the image sensor 103. The vertical synchronization signal transmitted from the image sensor 103 is received by the output controller CTRL in one field cycle. The output controller CTRL transmits the matrix coefficient read by the selection unit SEL to the calculation unit 210B1 at the timing when the vertical synchronization signal is received.

  FIG. 6 is a timing chart showing the operation timing of the color conversion circuit 210B. In FIG. 6, time elapses from the left side to the right side. Consider a case where the first optical filter 206a is selected by the initial state or the operator. In this case, the first optical filter 206a is disposed on the optical path of the illumination light. Therefore, the matrix coefficient M1 corresponding to normal light is read by the selection unit SEL and transmitted to the calculation unit 210B1. The calculation unit 210B1 executes matrix calculation processing using the matrix coefficient M1. When the operator performs a switching operation to switch the first optical filter 206a to the second optical filter 206b on the front panel 212 (time t1), the selection unit SEL reads the matrix coefficient M2 and transmits it to the output controller CTRL. The output controller CTRL holds the matrix coefficient M2 received from the selection unit SEL. When the output controller CTRL receives the vertical synchronization signal while holding the matrix coefficient M2 (time t2), the output controller CTRL transmits the held matrix coefficient M2 to the arithmetic unit 210B1. When the calculation unit 210B1 receives the matrix coefficient M2 from the output controller CTRL, the calculation unit 210B1 switches the matrix coefficient to be applied to the matrix calculation processing to the matrix coefficient M2.

  As described above, in this embodiment, when the operator performs the filter switching operation, the matrix coefficient applied to the matrix calculation processing is always synchronized with the vertical synchronization signal (the field is changed) regardless of the operation timing. At the timing of switching). Therefore, there is no problem that the observed video is temporarily disturbed by applying different matrix coefficients in one field and mixing regions having different colors in the image.

  The above is the description of the exemplary embodiments of the present invention. Embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes an embodiment that is exemplarily specified in the specification or a combination of obvious embodiments and the like as appropriate.

  In the present embodiment, the matrix coefficient is switched at the timing when the matrix calculation process for one field ends, but the present invention is not limited to this. For example, the matrix coefficient may be switched at the timing when the matrix calculation process for one frame ends. Specifically, a field identification signal is used instead of the vertical synchronization signal. The field identification signal is a signal indicating whether the RAW data transmitted from the image sensor 103 is the RAW data of the ODD or EVEN field. The output controller CTRL determines whether or not the calculation unit 210B1 has finished the matrix calculation process for one frame based on the field identification signal. The output controller CTRL transmits the matrix coefficient to the calculation unit 210B1 at the timing when the matrix calculation process for one frame of the calculation unit 210B1 is completed.

  In the present embodiment, the image sensor 103 is a CCD image sensor having a complementary color checkered pixel arrangement, but the present invention is not limited to this. The image sensor 103 may be, for example, a well-known Bayer type CCD image sensor. The image sensor 103 may be a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

  In this embodiment, the pixel signal is read from the image sensor 103 based on the interlace method, but the present invention is not limited to this. The pixel signal may be read based on a progressive method. In this case, the matrix coefficient applied and used in the calculation unit 210B1 is switched at the timing when the matrix calculation process for one frame is completed.

  The filter turret 206 includes two optical filters 206a and 206b, but the present invention is not limited to this. The filter turret 206 may have more than two optical filters. Further, the spectral characteristics of the first optical filter 206a and the second optical filter 206b shown in FIG. 3 are examples of the present embodiment, and the present invention is not limited to this.

  Further, in the present embodiment, one matrix coefficient is stored in the coefficient switching unit 210B2 for one optical filter, but the present invention is not limited to this. A plurality of matrix coefficients may be stored in the coefficient switching unit 210B2 for one optical filter. In this case, when the operator performs an operation to switch the matrix coefficient on the front panel 212, the optical filter arranged in the optical path of the illumination light is not switched, and only the matrix coefficient applied in the calculation unit 210B1 is vertically synchronized. It switches at the synchronized timing of the signal.

1 Endoscope System 100 Electronic Scope 101 Objective Optical System 102 Illumination Optical System 103 Image Sensor 104 AFE (Analog Front End)
105 Light Guide 106 Electrical Connector 107 Electrical Connector 200 Processor 201 System Controller 202 Timing Controller 203 Light Source Driver 204 Light Source 205 Condensing Lens 206 Filter Turret 206a First Optical Filter 206b Second Optical Filter 207 Motor Driver 208 Motor 209 Photointerrupter 210 Signal Processing Circuit 210A demosaic processing circuit 210B color conversion circuit 210B1 arithmetic unit 210B2 coefficient switching unit 210C color correction circuit 210D noise removal circuit 211 video signal generation circuit 212 front panel 300 monitor

Claims (6)

Wavelength characteristic changing means for changing the wavelength characteristic of illumination light for illuminating the subject;
Input receiving means for receiving an instruction input for instructing a change of the wavelength characteristic from a user;
Color conversion means for sequentially performing color conversion processing based on matrix coefficients for video signals sequentially input from a predetermined imaging device at a predetermined cycle;
With
When the input means accepts the instruction input, the matrix coefficient used in the color conversion means is changed based on the instruction input at the timing when the field or frame of the video signal is switched . Switch to a matrix coefficient according to the wavelength characteristics ,
Endoscope system . Receiving a synchronization signal synchronized with a field period or a frame period of the video signal from the imaging device;
After the input accepting unit accepts the instruction input, the matrix coefficient is switched at a timing when the synchronization signal is received.
The endoscope system according to claim 1. The synchronization signal is a vertical synchronization signal of the video signal;
When the input reception unit detects the instruction input and then detects the falling edge of the vertical synchronization signal, the matrix coefficient used in the color conversion unit is switched to the matrix coefficient corresponding to the wavelength characteristic after the change,
The endoscope system according to claim 2. A matrix coefficient storage means for storing a plurality of types of matrix coefficients;
When the input receiving unit receives the instruction input, the matrix coefficient corresponding to the wavelength characteristic of the illumination light after being changed based on the instruction input is read from the matrix coefficient storage unit,
Switching the matrix coefficient used in the color conversion means to the matrix coefficient read from the matrix coefficient storage means at the timing when the field or frame of the video signal is switched;
The endoscope system according to any one of claims 1 to 3. A light source that emits illumination light for illuminating the subject;
The wavelength characteristic changing means is
A plurality of types of filters that change the wavelength characteristics of the illumination light into different wavelength characteristics;
Filter selection means for selecting any one of the plurality of types of filters based on the instruction input;
Anda filter arrangement means for arranging the selected filter in the optical path of the illumination light,
Switching the matrix coefficient used in the color conversion means to a matrix coefficient corresponding to the filter selected by the filter selection means at the timing when the field or frame of the video signal is switched;
The endoscope system according to any one of claims 1 to 4. Further comprising an electronic endoscope having an image pickup device for sequentially generating and outputting the video signal at a predetermined period,
The endoscope system according to any one of claims 1 to 5 .

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