JP2016015995A - Electronic endoscope system, and processor for electronic endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the precision of the color correction of an electronic endoscope image.SOLUTION: An electronic endoscope system comprises: a storage part adapted to store a correction value for correcting the hue of the picture signal of an endoscope image; and a correction part for correcting the hue of the image signal on the basis of the correction value stored in the storage part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electronic endoscope system and an electronic endoscope processor for capturing an endoscope image, and more particularly to color correction processing of an image signal in an electronic endoscope system or the like.

  Electronic endoscopes are used for observation and treatment inside the human body. In electronic endoscopic observation, it is necessary to accurately distinguish a lesion from a normal site. The lesion often has a color tone different from that of a normal part due to, for example, angiogenesis. Patent Document 1 has a function of supporting endoscopic image diagnosis by identifying a site that is highly likely to be a lesion based on color information of an endoscopic image and highlighting the site. An electronic endoscope system is described.

  As described above, in order to accurately specify a lesioned part or the like based on the color information of the endoscope image, an endoscope image having accurate color information is acquired at least in a color region used for specifying the lesioned part or the like. There is a need. A conventional electronic endoscope system is provided with a white balance correction function as a function of correcting color information of an endoscope image.

JP 2010-115243 A

  Since the white balance correction is to perform color correction at only one point (for example, white) on the achromatic color axis, it is not possible to correct the hue error of the chromatic color. For this reason, in a conventional electronic endoscope system having only a white balance correction function as a function for correcting color information, there is a large error in color information, which makes the accuracy of identifying a lesion or the like low.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to improve a color correction accuracy of an electronic endoscopic image, thereby causing a lesion portion based on color information of the electronic endoscopic image. The purpose is to improve the accuracy of identifying the like.

  According to an embodiment of the present invention, a storage unit that stores a correction value for correcting a hue of an image signal of an endoscopic image, and a hue of the image signal is corrected based on the correction value stored in the storage unit. And an electronic endoscope system including a correction unit.

  In the above electronic endoscope system, the correction value may be one that corrects individual differences in hues of image signals set individually in the electronic endoscope system.

  The electronic endoscope system may further include a calibration unit that captures a color chart of a predetermined color to acquire a calibration image signal and calculates a correction value based on the calibration image signal. Good.

  In the above electronic endoscope system, the predetermined color may be a red color peculiar to blood.

  In the electronic endoscope system described above, the calibration unit acquires calibration image signals for a plurality of predetermined colors having different hues, and the correction is performed so that errors after correction in the plurality of predetermined colors are equal to or less than a predetermined value. It is good also as a structure which calculates a value.

  In the above electronic endoscope system, the correction value includes a correction angle for correcting the hue and a correction coefficient for correcting the saturation, and the correction unit corrects the saturation of the image signal based on the correction coefficient. It is good also as composition to do.

  The above electronic endoscope system includes an image processing unit that performs image processing with color change on an image signal, and the storage unit is a first correction value that is a correction value suitable for image processing. And a second correction value that is a correction value suitable for a case where image processing is not performed, and a correction unit performs correction based on the first correction value when image processing is performed, When the process is not performed, the correction may be performed based on the second correction value.

  The storage unit stores a plurality of correction values according to the type of light source used for illumination of the subject, and the correction unit selects and selects one corresponding to the type of light source to be used from the plurality of correction values. The hue of the image signal may be corrected based on the correction value.

  The above electronic endoscope system may include an index calculation unit that calculates an index for each pixel based on the corrected image signal.

  In the electronic endoscope system described above, the index may be configured to be an index correlating with the hemoglobin concentration in the living tissue imaged in the endoscopic image.

  The electronic endoscope system includes an electronic scope that generates an image signal, and a processor that processes the image signal to generate a video signal, a storage unit is provided in the electronic scope, and a correction unit is provided in the processor. It is good also as a structure provided.

  Further, according to the embodiment of the present invention, in the above electronic endoscope system, the correction value for correcting the hue of the image signal of the endoscopic image is stored, and the correction value is stored in the storage unit. There is provided a processor for an electronic endoscope comprising a correction unit that corrects the hue of an image signal based on a correction value.

  According to the embodiment of the present invention, color correction of an electronic endoscope image can be performed with high accuracy. Thereby, the precision which identifies a lesioned part etc. based on the color information of an electronic endoscope image can be improved.

1 is an external view of an electronic endoscope system according to an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of an electronic endoscope system according to an embodiment of the present invention. It is a block diagram which shows the detailed structure of the signal processing part of the processor which concerns on embodiment of this invention. It is a Cb-Cr color plan view for explaining advanced color correction processing according to the embodiment of the present invention. It is a * b * color top view explaining the modification of the advanced color correction process which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an external view of an electronic endoscope system 1 according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of the electronic endoscope system 1. The electronic endoscope system 1 includes an electronic scope 100, a processor 200, and a monitor 300 (FIG. 2). The electronic scope 100 and the monitor 300 are each connected to the processor 200.

  The processor 200 supplies an illumination light for illuminating the inside of the body to the electronic scope 100, an image signal processing apparatus that processes an image signal from the electronic scope 100 and generates a video signal supplied to the monitor 300, and Is an apparatus that is integrally provided. The light source device and the image signal processing device may be configured separately.

  As shown in FIG. 1, the processor 200 is provided with a connector portion 20 for connecting to the electronic scope 100. A connector unit 10 for connecting to the connector unit 20 of the processor 200 is provided at one end (base end) of the electronic scope 100. By mechanically connecting the connector unit 10 and the connector unit 20, the electronic scope 100 and the processor 200 are electrically and optically connected.

  A flexible insertion section 11 is provided at the other end (tip) of the electronic scope 100. In the vicinity of the distal end of the insertion portion 11, a bending portion 14 is provided that bends in response to a remote operation from the hand operation portion 13 connected to the proximal end of the insertion portion 11. The bending mechanism of the bending portion 14 is a well-known mechanism incorporated in a general endoscope, and the bending portion 14 is pulled by pulling the operation wire in conjunction with the rotation operation of the bending operation knob provided in the hand operation portion 13. Is bent. A distal end portion 12 including a solid-state image sensor 108 is connected to the distal end of the bent portion 14. When the direction of the distal end portion 12 changes according to the bending operation of the bending portion 14 by the rotation operation of the bending operation knob, the imaging region by the electronic scope 100 moves.

  As shown in FIG. 2, the electronic scope 100 includes an LCB (Light Carrying Bundle) 102 disposed over a substantially entire length from the connector portion 10 to the distal end portion 12. The LCB 102 is an optical fiber bundle, and guides the illumination light supplied from the processor 200 to the distal end portion 12 of the electronic scope 100.

  The distal end portion 12 of the electronic scope 100 includes a light distribution lens 104, an objective lens 106, a solid-state imaging device 108, and a preamplifier 110. The light distribution lens 104 is disposed to face the front end surface of the LCB 102, and illuminates the subject by diverging illumination light emitted from the front end surface of the LCB 102. The objective lens 106 collects the return light from the subject and forms an optical image on the light receiving surface of the solid-state image sensor 108.

  The solid-state image sensor 108 is an interlaced single-plate color CCD (Charge Coupled Device) image sensor having a complementary color checkered pixel arrangement. The solid-state image sensor 108 generates and accumulates electric charges according to the amount of light of the optical image formed on each pixel on the light receiving surface, and is an analog composed of color signals of yellow Ye, cyan Cy, green G, and magenta Mg. Output the imaging signal. The analog image pickup signal is a signal for transferring so-called RAW data (RAW image), and each pixel of the analog image pickup signal has only color information of any one of yellow Ye, cyan Cy, green G, and magenta Mg. have. The analog imaging signal is amplified by the preamplifier 110 and then transmitted to the connector unit 10.

  Note that the color array of the solid-state image sensor 108 may be, for example, a Bayer type. Further, the solid-state image sensor 108 may be replaced with another type such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor.

  The connector unit 10 includes a CCD signal processing unit 112 and a memory 114. The CCD signal processing unit 112 supplies a drive signal to the solid-state image sensor 108, converts an analog image signal output from the solid-state image sensor 108 into a digital image signal, and transmits the digital image signal to the processor 200. In addition, the CCD signal processing unit 112 accesses the memory 114 to read out the unique information of the electronic scope 100 and outputs it to the processor 200. The unique information of the electronic scope 100 recorded in the memory 114 includes, for example, the number of pixels and sensitivity of the solid-state image sensor 108, an operable frame rate, a model number, a correction value (correction angle Δθ) described later, and the like.

  As illustrated in FIG. 2, the processor 200 includes a system controller 202, a timing controller 204, a signal processing unit 220, a memory 201, and an operation panel 218. The system controller 202 controls the overall operation of the electronic endoscope system 1 by reading and executing various programs stored in the memory 201. Further, the system controller 202 changes various settings of the electronic endoscope system 1 in accordance with instructions from the user (surgeon or assistant) input to the operation panel 218. The timing controller 204 supplies clock pulses to the CCD signal processing unit 112 and the signal processing unit 220 according to the timing control by the system controller 202. The signal processing unit 220 processes the image signal of the endoscopic image supplied from the electronic scope 100 and generates a video signal supplied to the monitor 300.

  The processor 200 further includes a lamp power igniter 206, a lamp 208, a condenser lens 210, and a diaphragm 212. The lamp 208 is driven by electric power supplied from the lamp power igniter 206, and emits illumination light. A high-intensity lamp such as a xenon lamp, a halogen lamp, or a metal halide lamp is suitable for the lamp 208. Further, as the lamp 208, an LED (Light Emitting Diode) lamp or a narrow band light source (light source with a band limiting filter) can be used. The illumination light radiated from the lamp 208 passes through the stop 212 while being condensed by the condenser lens 210 and is adjusted to an appropriate amount of light, and then enters the incident end of the LCB 102.

  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 aperture 212 is operated by the motor 214 to change the opening degree so that the image displayed on the display screen of the monitor 300 has an appropriate brightness. The amount of illumination light supplied to the LCB 102 is limited according to the opening of the diaphragm 212. The appropriate video brightness reference is set according to the brightness adjustment operation of the operation panel 218 by the operator. A known dimming circuit (not shown) provided in the signal processing unit 220 controls the driver 216 based on the setting by the luminance adjustment operation, and performs luminance adjustment.

  There are various configurations for the operation panel 218. Specific configurations of the operation panel 218 include, for example, 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.

  The system controller 202 performs various calculations based on the unique information of the electronic scope 100 and generates a control signal. The system controller 202 uses the generated control signal to control the operation and timing of various circuits in the processor 200 so that processing suitable for the electronic scope connected to the processor 200 is performed.

  The CCD signal processor 112 drives and controls the solid-state image sensor 108 at a timing synchronized with the frame rate of the video processed on the processor 200 side in accordance with the clock pulse supplied from the timing controller 204.

  FIG. 3 is a block diagram illustrating a detailed configuration of the signal processing unit 220. The signal processing unit 220 includes a preprocessing unit 222, a post processing unit 224, and an image composition unit 226. The pre-processing unit 222 converts a digital image pickup signal (RAW data) from the electronic scope 100 into an image signal and performs various color adjustment processes. Based on the image signal output from the preprocessing unit 222, the post processing unit 224 calculates an index indicating the possibility of an abnormal site such as a lesion (or the degree of abnormality) for each pixel, Image processing such as emphasizing an abnormal part is performed on the image signal. In addition, the image composition unit 226 performs screen composition processing so that an endoscopic image drawn based on an image signal and an index image obtained by imaging an index of each pixel are displayed on one screen.

  The preprocessing unit 222 includes a color interpolation unit 222a, a matrix conversion unit 222b, a basic color correction unit 222c, a color space conversion unit 222d, and an advanced color correction unit 222e according to the embodiment of the present invention.

  The color interpolation unit 222a performs color interpolation processing on the digital imaging signal (RAW data) from the electronic scope 100, and converts it into a color signal CyMgYeG and a luminance signal Y. Specifically, the color interpolation unit 222a generates color signal CyMgYeG and luminance signal Y by interpolating color information from surrounding pixels for each pixel of the digital imaging signal having only single color information. .

  The matrix conversion unit 222b converts the color signal CyMgYeG into the primary color signal RGB using the color matrix.

  The basic color correction unit 222c performs white balance correction on the primary color signal RGB. In addition to the white balance correction (or in place of the white balance correction), the basic color correction unit 222c can also perform color adjustment using a tone curve such as gamma correction.

  Based on the corrected primary color signal RGB output from the basic color correction unit 222c and the luminance signal Y output from the color interpolation unit 222a, the color space conversion unit 222d uses the luminance signal Y and the two color difference signals Cb and Cr. An image signal YCbCr1 in the YCbCr color space to be expressed is generated and output.

  The output from the color space conversion unit 222d is branched into two, one being input to the advanced color correction unit 222e and the other being input to the post-processing unit 224.

  The advanced color correction unit 222e uses the correction values (correction angle Δθ and correction coefficient α) held in the memory 114 of the electronic scope 100 to perform the advanced color correction processing according to the embodiment of the present invention to be described later on the image signal YCbCr1. I do. In the memory 114 of the electronic scope 100, correction values for advanced color correction processing acquired by calibration processing performed at the time of factory shipment inspection or maintenance are recorded. The image signal YCbCr2 after the advanced color correction process output from the advanced color correction unit 222e is input to the post-processing unit 224.

  The post-processing unit 224 includes a selector 224a, an image processing unit 224b, and an index calculation unit 224c. The image signal YCbCr1 output from the color space conversion unit 222d of the preprocessing unit 222 and the image signal YCbCr2 output from the advanced color correction unit 222e are respectively input to the selector 224a. Under the control of the system controller 202, the selector 224a selects either the image signal YCbCr2 after the advanced color correction process from the advanced color correction unit 222e or the image signal YCbCr1 before the advanced color correction process from the color space conversion unit 222d. This is selected and supplied to the image processing unit 224b and the index calculation unit 224c.

  The image signal YCbCr2 subjected to the advanced color correction processing is advantageous for improving the accuracy of the blood index, which will be described later, but is displayed on the monitor 300 because the specific hue used for calculating the blood index is corrected. There is a possibility that the color of the generated image will be unnatural. Therefore, by providing the selector 224a, when only normal endoscopic observation is performed without analyzing the blood index, the image signal YCbCr1 before the advanced color correction processing from the color space conversion unit 222d can be switched. It has become.

  In addition, without providing the selector 224a, for example, the image signal YCbCr1 before the advanced color correction processing from the color space conversion unit 222d is input to the image processing unit 224b, and the image signal after the advanced color correction processing from the advanced color correction unit 222e. YCbCr2 may be input to the index calculation unit 224c (that is, the image signal YCbCr1 before the advanced color correction process is always used for monitor display). Further, the output from the color space conversion unit 222d may not be branched, and only the image signal YCbCr2 after the advanced color correction processing from the advanced color correction unit 222e may be supplied to the image processing unit 224b and the index calculation unit 224c. .

  The image processing unit 224b performs various types of image processing suitable for endoscopic observation, such as tone enhancement processing (TE processing) described in JP2013-005884A, for example. The user can arbitrarily set whether or not to execute various image processing by the image processing unit 224b.

  The index calculation unit 224c calculates an index (lesion index) indicating a relationship with a specific lesion from each pixel value of the image signal YCbCr2. For example, inflamed or cancerous lesions have a greater blood volume than normal sites due to angiogenesis. Specifically, the concentration of hemoglobin contained in the living tissue per unit area is high. Therefore, an image of a lesioned part such as an inflamed part has a strong reddish color specific to blood (hemoglobin) compared to an image of a normal part. Therefore, the strength (saturation) of the color (hue) peculiar to blood in the endoscopic image is an effective parameter for discriminating between a lesioned part such as an inflamed part and a normal part. The index calculation unit 224c calculates a hue difference from the hue θvessel peculiar to blood for each pixel of the image signal YCbCr2, and calculates an index (blood index) indicating the possibility of being a lesion based on the hue difference. The relationship between the hue difference and the index is determined clinically in advance.

  Since the index calculation unit 224c calculates an index for each pixel, an index image (grayscale image) having the index as a pixel value is obtained.

  The image synthesizing unit 226 generates a monitor display screen by synthesizing the endoscopic image output from the image processing unit 224b and the index image output from the index calculating unit 224c. The image composition unit 226 generates an overlay display image composition unit 226a that generates an overlay display image in which an index image is superimposed on an endoscope image, and two screens that generate a two-screen display image in which the endoscope image and the index image are arranged. A display image composition unit 226b and a selector 226c are provided. Outputs from the image processing unit 224b and the index calculation unit 224c of the post-processing unit 224 are input to the overlay display image synthesis unit 226a and the two-screen display image synthesis unit 226b, respectively. The outputs of the overlay display image composition unit 226a and the two-screen display image composition unit 226b are input to the selector 226c, respectively. The selector 226 c selects either the output of the overlay display image composition unit 226 a or the output of the two-screen display image composition unit 226 b under the control of the system controller 202, and supplies it to the monitor 300. Thereby, the overlay display image and the two-screen display image can be switched and displayed on the monitor 300.

  Note that the overlay display image composition unit 226a does not generate an overlay display image, and directly uses the image signal (normal endoscope image) from the image processing unit 224b and the image signal (index image) from the index calculation unit 224c. It is also configured to be able to output. Therefore, only a normal endoscopic image or index image can be displayed on the monitor 300.

  Next, calibration processing and advanced color correction processing according to the embodiment of the present invention performed in the advanced color correction unit 222e will be described. The advanced color correction process according to the present embodiment is a process for correcting a hue of an endoscopic image that cannot be corrected by a white balance correction process (particularly, a hue shift due to individual differences in characteristics of the solid-state image sensor 108). The advanced color correction process is performed using correction values (correction angle Δθ, correction coefficient α) stored in the memory 114 of the electronic scope 100.

  First, a method for obtaining a correction value (correction angle Δθ, correction coefficient α) will be described. The correction value is acquired by a calibration process performed at the time of factory shipment inspection or maintenance of the electronic endoscope system 1. The calibration process is performed by imaging a color chart of a predetermined reference color (chromatic color) by the electronic endoscope system 1. In the present embodiment, calibration processing is performed using a color chart of a hue θvessel peculiar to blood used for calculation of a blood index by the index calculation unit 224c. By performing the calibration process in the hue θvessel, the accuracy of the color information of the corrected image signal YCbCr2 can be made particularly high in θvessel and the hue in the vicinity thereof, and as a result, the blood index is calculated by the index calculation unit 224c. It becomes possible to carry out with high accuracy.

  FIG. 4 is a Cb—Cr color plan view for explaining the advanced color correction processing and calibration processing of the present embodiment. The reference values indicated by white circles in the figure are color information (saturation rvessel, hue θvessel) of the color chart in the Cb-Cr color space. The actual measurement values indicated by black circles in the figure are color information (saturation rmeas, hue θmeas) of the image signal YCbCr1 obtained by imaging the color chart by the electronic endoscope system 1. The hue θ and the saturation r are calculated from the color differences Cb and Cr by the following formulas (1) and (2), respectively.

  The correction angle Δθ and the correction coefficient α are calculated by the following formulas (3) and (4), respectively, and stored in the memory 114 of the electronic scope 100.

  Next, a method of advanced color correction processing will be described. In the advanced color correction process, first, for each pixel of the image signal YCbCr1 from the color space conversion unit 222d, the hue θ and the saturation r are calculated by the above formulas (1) and (2), respectively.

  Next, the correction angle Δθ stored in the memory 114 of the electronic scope 100 is added to the hue θ calculated by Equation (1) to obtain a corrected hue θ ′. Further, the saturation r calculated by Equation (2) is multiplied by the correction coefficient α stored in the memory 114 to obtain a corrected saturation r ′. The hue θ ′ and saturation r ′ after the advanced color correction process are described by the following equations (5) and (6), respectively.

  By performing such advanced color correction processing, the accuracy of the color information of the image signal is improved. As a result, the accuracy of various processing such as index calculation processing using the color information of the image signal can be improved. it can.

  In this embodiment, the advanced color correction process is performed in the YCbCr color space. However, the present invention is not limited to this configuration, and the advanced color correction process can be performed using, for example, the CIE 1976 L * a * b * color space, CIE LCh. The color space, CIE 1976 L * u * v * color space, HSV (hue, saturation, value) color space, and sRGB color space can be used.

In the present embodiment, image processing (for example, TE processing) accompanied by a color change is performed by the image processing unit 224b in accordance with a user setting. The appropriate correction value for the advanced color correction process is different depending on whether or not image processing involving color change is performed. In the present embodiment, both the correction value (Δθ ₀ , α ₀ ) suitable for the case where the TE process is not performed and the correction value (Δθ ₁ , α ₁ ) suitable for the case where the TE process is performed are stored in the memory of the electronic scope 100. 114. When the TE process is not performed, the correction values (Δθ ₀ , α ₀ ) are read from the memory 114 and used. When the TE process is performed, the correction values (Δθ ₁ , α ₁ ) are read. It is issued and used. The correction values (Δθ ₀ , α ₀ ) are acquired by a calibration process that is executed under conditions where TE processing is not performed, and the correction values (Δθ ₁ , α ₁ ) are executed under conditions where TE processing is performed. Obtained by calibration processing.

  Also, the correction value suitable for the advanced color correction process varies depending on the type of light source used. When the processor 200 includes a plurality of types of light sources (or when a plurality of types of external light sources are switched and used), a correction value is stored in the memory 114 for each type of light source, and the correction value is determined according to the type of light source used A configuration for selecting a correction value to be used is adopted.

  In the above-described embodiment, since the index is calculated based on the hue difference from one reference point on the color space, the advanced color correction process is performed only on this one reference point. However, for example, when the index calculation process or the like is performed on the basis of a region having a certain spread in the color space, it is desired to reduce the error of the color information over the entire region on the reference color space. In such a case, the error is not more than a predetermined value not only for one point in the area on the color space to be used but also for a plurality of points in the area (for example, three points at the center and both ends of the hue area to be used). It is desirable to perform calibration such that

  FIG. 5 is an a * b * color plan view for explaining a modification of the calibration process performed at a plurality of points in this way. In the modification of FIG. 5, calibration processing and advanced color correction processing are performed in the CIE 1976 L * a * b * color space.

  In this modified example, in the index calculation processing by the index calculation unit 224c, when the pixel value is plotted inside the reference region R shown in FIG. 5 for each pixel of the image signal YCbCr2, “suspected abnormal part” When “1” meaning “I” is given and plotted outside the reference region R, “0” meaning “normal part” is given. Therefore, the calibration process is performed using a color chart of three colors of the median value θc, the upper limit value θc + 40 °, and the lower limit value θc−40 ° of the hue of the reference region R. Specifically, the correction angle Δθ is determined so that the hue error after the advanced color correction process is within ± 10 ° for all three colors. According to this configuration, a point that has almost no possibility of being an abnormal part greatly deviating from the reference region R is not determined as “suspected abnormal part”.

  The above is the description of the embodiment 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 above embodiment, the correction value is stored in the memory 114 of the electronic scope 100. However, the correction value may be stored in a storage device (for example, the memory 201) included in the processor 200.

  In addition, the CCD signal processing unit 112 in the above embodiment may be integrated into the preprocessing unit 222. Further, both the CCD signal processing unit 112 and the preprocessing unit 222 may be provided in the electronic scope 100, or both may be provided in the signal processing unit 220 of the processor 200.

  In the above-described embodiment, a lesioned part or the like is specified based on a red hue specific to hemoglobin that increases due to angiogenesis, but another hue (for example, a fluorescent agent that binds to a lesioned part is specific to the fluorescent agent. A configuration may be used in which a lesion or the like is specified based on (hue).

In the above embodiment, the correction of the hue θ is performed by adding the correction value Δθ, and the correction of the saturation r is performed by multiplying by the correction coefficient α, but the present invention is limited to this configuration. Instead, the hue θ may be corrected by, for example, multiplying by a correction coefficient β (β = θ _vessel / θ _meas ), and the saturation r may be corrected by, for example, a correction value Δr (Δr = r _vessel −r _A configuration may be made by adding _meas ).

  In the above-described embodiment, both the hue θ and the saturation r are corrected in the advanced color correction process. However, only the hue θ may be corrected.

  In the above modification, a configuration is adopted in which the correction angle Δθ is determined so that the corrected hue error at a plurality of points on the color space to be calibrated is equal to or less than a predetermined value. It is not limited to this configuration. For example, a configuration in which the correction angle Δθ is determined so as to minimize the maximum value of the corrected hue error at a plurality of points on the color space to be calibrated, or the sum of corrected hue errors is minimized. Alternatively, a configuration for determining the correction angle Δθ may be employed.

1 Electronic Endoscope System 100 Electronic Scope 200 Processor

Claims (12)

A storage unit that stores a correction value for correcting the hue of the image signal of the endoscopic image;
A correction unit that corrects the hue of the image signal based on the correction value stored in the storage unit;
Electronic endoscope system equipped with. The correction value is set individually for the electronic endoscope system, and corrects individual differences in hues of image signals.
The electronic endoscope system according to claim 1.   The calibration unit according to claim 1, further comprising: a calibration unit that captures a color chart of a predetermined color to acquire a calibration image signal, and calculates the correction value based on the calibration image signal. Electronic endoscope system. The predetermined color is blood-specific red,
The electronic endoscope system according to claim 3. The calibration unit acquires calibration image signals for a plurality of the predetermined colors having different hues, and calculates the correction value so that an error after correction in the plurality of predetermined colors is equal to or less than a predetermined value;
The electronic endoscope system according to claim 3 or 4, characterized by the above. The correction value includes a correction angle for correcting the hue and a correction coefficient for correcting the saturation,
The correction unit corrects the saturation of the image signal based on the correction coefficient;
The electronic endoscope system according to any one of claims 1 to 5, wherein the electronic endoscope system is configured as described above. An image processing unit that performs image processing with color change on the image signal,
The storage unit stores a first correction value that is the correction value suitable when the image processing is performed and a second correction value that is the correction value suitable when the image processing is not performed. ,
The correction unit corrects based on the first correction value when the image processing is performed, and corrects based on the second correction value when the image processing is not performed.
The electronic endoscope system according to any one of claims 1 to 6, wherein the electronic endoscope system is configured as described above. The storage unit stores a plurality of correction values according to the type of light source used to illuminate the subject,
The correction unit selects one corresponding to the type of light source to be used from the plurality of correction values, and corrects the hue of the image signal based on the selected correction value.
The electronic endoscope system according to any one of claims 1 to 7, wherein the electronic endoscope system is characterized in that: An index calculation unit that calculates an index for each pixel based on the corrected image signal;
The electronic endoscope system according to any one of claims 1 to 8, wherein the electronic endoscope system is configured as described above. The index is an index that correlates with the hemoglobin concentration in the living tissue imaged in the endoscopic image.
The electronic endoscope system according to claim 9. An electronic scope for generating the image signal;
A processor that processes the image signal to generate a video signal;
With
The storage unit is provided in the electronic scope,
The correction unit is provided in the processor;
The electronic endoscope system according to any one of claims 1 to 10, wherein the electronic endoscope system is characterized in that A correction value acquisition unit that acquires a correction value for correcting the hue of the image signal of the endoscopic image;
A correction unit that corrects the hue of the image signal based on the correction value acquired by the correction value acquisition unit;
An electronic endoscope processor.

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