JP6159817B2 - Calibration method and endoscope system - Google Patents

Description

  The present invention relates to a calibration method and an endoscope system that are performed to match the color of an endoscopic image with a target color.

  In the medical field, an endoscope system including a light source device, an endoscope, and a processor device is widely used. As for an endoscope, an electronic endoscope including an image sensor that images an observation target and outputs an image signal is generally used. About this imaging sensor, there are individual differences, and the spectral sensitivity differs for each endoscope. There are also individual differences in the light guide used to guide the illumination light from the light source device to the endoscope, and the transmission characteristics are different for each endoscope. Due to individual differences among endoscopes such as variations in spectral sensitivity of the image sensor, the color of the endoscopic image may not be a target color preset by the user.

  To match the color of the endoscopic image to the target color, measure the reading characteristics of the observation target for each endoscope, and based on the measurement results, the color for matching the color of the endoscopic image to the target color It is necessary to perform color correction processing after setting correction processing conditions. As a method for setting the conditions for color correction processing, for example, as shown in Patent Document 1, a method using a color chart in which a relationship with colorimetric data is predetermined can be considered. According to this method, the color chart is photographed, and the color correction processing conditions are set so that the relationship between the read image obtained by the photographing and the colorimetric data is as intended.

Japanese Patent No. 2773498

  In order to accurately match the color of the endoscopic image to the target color, more color charts are required, and the shooting conditions such as distance, angle, and brightness are strictly determined according to each color chart. After setting, it is necessary to set conditions for color correction processing. Therefore, the method of setting the color correction processing conditions using the color chart takes time and effort as the accuracy of the color correction processing is increased.

  On the other hand, white balance adjustment for the purpose of adjusting not only the whole color but only white is widely performed. Although the accuracy is inferior to the case where color reproduction is corrected using a color chart, it is possible to tolerate a color reproduction deviation considerably by correcting the perceived white deviation, and only white is measured. The advantage is that preparation and work can be simplified. Accordingly, there is a demand for color correction processing conditions that can be set with simple preparation and work, such as white balance adjustment, and with the same accuracy as when a plurality of color charts are used.

  The present invention is a calibration that can set conditions for color correction processing with simple preparation and work, such as white balance adjustment, and can perform color correction with the same accuracy as when a plurality of color charts are used. It is an object to provide a method and an endoscope system.

To achieve the above object, the present invention provides an endoscope including a color correction processing unit that performs color correction processing for converting a first color image signal into a second color image signal for enabling display of a target color. The system calibration method includes an illumination light generation step, an illumination step, an image signal acquisition step, and a condition setting step. In the illumination light generation step, a plurality of illumination lights having different wavelength bands are emitted from a plurality of semiconductor light sources at a specific light amount ratio to combine the plurality of illumination lights into a color chart color light. Is generated. In the illumination step, a white reference subject is illuminated with the color chart equivalent color light generated in the illumination light generation step. In the image signal acquisition step, the white reference object being illuminated with the color chart equivalent color light in the illumination step is imaged by an imaging sensor to obtain an image signal for the first calibration. In the condition setting step, a condition for color correction processing is set based on the first calibration image signal acquired in the image signal acquisition step. A color chart is shown in the light quantity ratio-image signal table showing the relationship between the light quantity ratio between the plurality of illumination lights and the image signal obtained when the white reference subject is imaged with the plurality of illumination lights having the light quantity ratio. A color chart equivalent color light quantity ratio setting step for setting a light quantity ratio corresponding to the second calibration image signal obtained when imaged by the imaging sensor as a specific light quantity ratio necessary for light emission of the color chart equivalent color light; Have.

  The color correction process is a matrix calculation for converting the first color image signal into the second color image signal. In the condition setting step, the matrix calculation is performed based on the first calibration image signal acquired in the image signal acquisition step. It is preferable to set the matrix coefficient to be used. In the condition setting step, it is preferable to set the matrix coefficient so that the first calibration image signal acquired in the image signal acquisition step approaches the target image signal.

  The plurality of semiconductor light sources preferably include an R-LED that emits red light, a G-LED that emits green light, and a B-LED that emits blue light. The plurality of semiconductor light sources include a first special light LED that emits first special light having a first wavelength band at least partially different from red light, green light, and blue light, red light, green light, blue light, It is preferable to further include a plurality of special light LEDs including at least one special light and a second special light LED that emits second special light having a second wavelength band that is at least partially different.

  The endoscope system emits white light by emitting at least R-LED, G-LED and B-LED, and special light by lighting at least the first and second special light LEDs. It is preferable to set a condition for color correction processing for each observation mode. It is preferable to perform a matrix operation based on the matrix coefficient set by the calibration method of the present invention. It is preferable to have a storage unit that stores the matrix coefficient and the scope ID of the endoscope in association with each other and an ID reading unit that reads out the scope ID of the endoscope.

The present invention provides an endoscope system including a color correction processing unit that performs a color correction process for converting a first color image signal into a second color image signal for enabling display of a target color. A color chart equivalent color light control unit, an image signal acquisition unit, a condition setting unit, and a light quantity ratio-image signal table . The plurality of semiconductor light sources emit a plurality of illumination lights having different wavelength bands. The color chart equivalent color light control unit controls a plurality of semiconductor light sources so as to emit a plurality of illumination lights at a specific light quantity ratio, thereby combining the plurality of illumination lights into a color chart color. Equivalent color light is generated . The image signal acquisition unit acquires a first reference image signal by capturing an image of a white reference object that is being illuminated with color chart-equivalent color light by an image sensor. The condition setting unit sets conditions for color correction processing based on the first calibration image signal acquired by the image signal acquisition unit. The light quantity ratio-image signal table shows a relationship between a light quantity ratio between a plurality of illumination lights and an image signal obtained when a white reference subject is imaged with a plurality of illumination lights having the light quantity ratio. In the light quantity ratio-image signal table, the light quantity ratio corresponding to the second calibration image signal obtained when the color chart is imaged by the imaging sensor is set as the specific light quantity ratio necessary for the emission of the color chart equivalent color light. To do.

  The color correction process is a matrix operation for converting the first color image signal into the second color image signal, and the condition setting unit performs the matrix operation based on the first calibration image signal acquired by the image signal acquisition unit. It is preferable to have a matrix coefficient setting unit for setting the matrix coefficient to be used.

  According to the present invention, using a plurality of semiconductor light sources, color chart equivalent color light corresponding to the color of the color chart is generated, the color chart equivalent color light is irradiated to the white reference subject, and the white reference subject is imaged. Since the color correction processing conditions are set based on the first calibration image signal obtained in this way, the color correction processing conditions can be set with simple preparation and work, such as white balance adjustment. Can do.

It is an external view of an endoscope system. It is a block diagram which shows the function of an endoscope system. 4 is a graph showing emission spectra of blue light B, green light G, and red light R. It is a table | surface which shows the light emission conditions of each LED at the time of each observation mode. It is a table | surface which shows the setting signal ratio at each observation mode. It is a block diagram which shows the function of a light source control part. It is a block diagram which shows the memory content of the memory in a light source control part. It is a graph which shows the relationship between a light source control signal and the light source control signal for light quantity linear. It is explanatory drawing which shows the setting method of the light source control signal for the brightness step n used at the time of normal observation mode. It is explanatory drawing which shows the setting method of the light source control signal for brightness step n used at the time of 1st special light observation mode. It is explanatory drawing which shows the setting method of the light source control signal for brightness step n used at the time of 2nd special light observation mode. It is explanatory drawing which shows the setting method of the light source control signal for brightness step n used at the time of 3rd special light observation mode. It is sectional drawing which shows the internal structure of integrating sphere ST. It is a top view which shows a color chart. It is a block diagram which shows the function of a normal image process part. It is a flowchart which shows the calibration method of this invention. It is a flowchart which shows the preparation method of the light control table for normal observation modes, a joint table, and a brightness | luminance linear table, and the setting method of a matrix coefficient. It is a flowchart which shows the flow which performs observation within an observation object using the joint table etc. which are obtained by the calibration method of this invention.

  As shown in FIG. 1, the endoscope system 10 includes an endoscope 12, a light source device 14, a processor device 16, a monitor 18, and a console 19. The endoscope 12 is optically connected to the light source device 14 and electrically connected to the processor device 16 via the universal cord 15. The endoscope 12 includes an insertion portion 12a to be inserted into an observation target, an operation portion 12b provided at the proximal end portion of the insertion portion 12a, a bending portion 12c and a distal end portion 12d provided at the distal end side of the insertion portion 12a. have. By operating the angle knob 12e of the operation unit 12b, the bending unit 12c performs a bending operation. With this bending operation, the tip 12d is directed in a desired direction.

  In addition to the angle knob 12e, the operation unit 12b is provided with a mode switching SW 13a and a zoom operation unit 13b. The mode switching SW 13a is used for switching operation among the normal observation mode, the special observation mode, and the calibration mode. The normal observation mode is a mode in which a normal image obtained by imaging the observation object using normal light such as white light is displayed on the monitor 18, and the special observation mode is an image of the observation object using light of a specific wavelength. The calibration mode is a mode for calibrating the contents of light source control, signal processing, and the like when the endoscope is mounted on the light source device 14 or the processor device 16. It is. The special observation modes include a first special light observation mode, a second special light observation mode, and a third special light observation mode. The zoom operation unit 13b is used for driving the zoom lens 51b (see FIG. 2), and expands the observation target by moving the zoom lens 51b to the tele side.

  The processor device 16 is electrically connected to the monitor 18 and the console 19. The monitor 18 outputs and displays image information and the like. The console 19 functions as a UI (user interface) that receives input operations such as function settings. The processor device 16 may be connected to an external recording unit (not shown) for recording image information and the like.

  An endoscope 100 different from the endoscope 12 can be attached to the light source device 14 and the processor device 16. The endoscope 100 includes an image sensor having a spectral sensitivity different from that of the image sensor 51c of the endoscope 12 (see FIG. 2). Other than that, it has substantially the same configuration as the endoscope 12.

  As shown in FIG. 2, the light source device 14 includes a B-LED (Blue Light Emitting Diode) 20, a G-LED (Green Light Emitting Diode) 21, an R-LED (Red Light Emitting Diode) 22, and the first special light. LED 23, second special light LED 24, third special light LED 25, light source control unit 27 that controls driving of these six LEDs 20 to 25, and an optical path that combines optical paths of light emitted from these six LEDs 20 to 25 A coupling portion 28 is provided. The light coupled by the optical path coupling unit 28 is irradiated to the observation target through the light guide 49 and the illumination lens 50a inserted into the insertion unit 12a. An LD (Laser Diode) may be used instead of the LED.

  The light guide 49 is built in the endoscope 12 and the universal cord 15, and propagates the light coupled by the optical path coupling unit 28 to the distal end 12 d of the endoscope 12. As the light guide 49, a multimode fiber can be used. As an example, a thin fiber cable having a core diameter of 105 μm, a cladding diameter of 125 μm, and a diameter of φ0.3 to 0.5 mm including a protective layer serving as an outer shell can be used.

  The B-LED 20 generates blue light B having a predetermined wavelength band in the blue band. The G-LED 21 generates green light G having a predetermined wavelength band in the green band. The R-LED 22 generates red light R having a predetermined wavelength band in the red band. The first special light LED 23 generates the first special light SA in the first wavelength band used in the first and second special light observation modes. The second special light LED 24 generates the second special light SB in the second wavelength band (wavelength band different from the first wavelength band) used in the first to third special light observation modes. The third special light LED 25 generates third special light SC having a third wavelength band (a wavelength band different from the first and second wavelength bands) used in the third special light observation mode.

  Of the above six types of light, as shown in FIG. 3, it is preferable that the blue light B has a wavelength range with a center wavelength of 430 to 480 nm and slightly on the short wavelength side. The green light G is preferably light having a wavelength range of 480 to 600 nm and close to a normal distribution. The red light R is preferably light having a center wavelength of 620 to 630 nm and a wavelength range of 600 to 650 nm.

  D / A 20a to 25a are provided between the LEDs 20 to 25 and the light source control unit 27, and each D / A 20a to 25a controls a digital light source control signal from the light source control unit 27 as an analog light source control. Convert to signal. Based on the converted analog light source control signal, the light emission conditions of the LEDs 20 to 25 are controlled. In addition, as light emission conditions, the light emission intensity and irradiation time of each LED20-25 are included.

  The light source control unit 27 transmits a light source control signal to each of the LEDs 20 to 25 to control light emission of each of the LEDs 20 to 25, and receives a brightness instruction signal from the brightness instruction signal generation unit 59 of the processor device, The light emission of each LED 20-25 is controlled so that the light quantity of each LED20-25 changes with the brightness step n of N steps. Here, the light source control signal m is composed of an M-bit digital signal, and the brightness instruction signal n is composed of an N-bit digital signal. Note that M is an integer of 2 or more and N or more, and m is an integer of 1 to M. N is an integer of 2 or more, and n is any integer of 1 to N.

  As shown in FIG. 4, the light source control unit 27 controls the LEDs 20 to 25 under light emission conditions that are different for each observation mode. Further, as shown in FIG. 5, the LEDs 20 to 25 are driven under the light emission conditions determined for each observation mode to illuminate the white subject portion WST (see FIG. 13) in the integrating sphere ST, and the white subject portion WST ( The signal ratio between the RGB image signals obtained when the image sensor 51c captures the image) is determined in advance as a set signal ratio.

  In the normal observation mode, the B-LED 20, G-LED 21, R-LED 22, first special light LED 23, and second special light LED 24 are turned on. A light signal emitted by driving these four LEDs 21 to 24 is applied to the white subject portion WST in the integrating sphere ST, and a signal ratio between RGB image signals obtained by imaging the white subject portion WST is set signal ratio. r1: g1: b1 is set.

  In the first special light observation mode, the G-LED 21, the first special light LED 23, and the second special light LED 24 are turned on. A signal between the G image signal and the B image signal obtained by irradiating the white subject portion WST in the integrating sphere ST with the light emitted by driving these three LEDs 21, 23, 24, and imaging the white subject portion WST. The ratio is set to the set signal ratio g2: b2.

  In the second special light observation mode, the G-LED 21, the R-LED 22, the first special light LED 23, and the second special light LED 24 are turned on. A light signal emitted by driving these four LEDs 21 to 24 is applied to the white subject portion WST in the integrating sphere ST, and a signal ratio between RGB image signals obtained by imaging the white subject portion WST is set signal ratio. r3: g3: b3 is set.

  In the third special light observation mode, the second special light LED 24 and the third special light LED 25 are turned on. Regarding the signal ratio between the G image signal and the B image signal obtained by irradiating the white subject portion WST in the integrating sphere ST with the light emitted by driving these two LEDs 24 and 25 and imaging the white subject portion WST. Is set to the set signal ratio g4: b4.

  As shown in FIG. 6, the light source control unit 27 includes an observation mode circuit 29 used in the normal observation mode and the special observation mode, a calibration circuit 30 used in the calibration mode, and a memory 31. Yes. The observation mode circuit 29 includes a B-LUT (Look Up Table) 32 connected to the B-LED 20, a G-LUT 33 connected to the G-LED 21, an R-LUT 34 connected to the R-LED 22, The first special light LUT 35 connected to the first special light LED 23, the second special light LUT 36 connected to the second special light LED 24, and the third special light connected to the third special light LED 25. LUT37.

  The LUTs 32 to 37 are used for the dimming table used for the light source control of the LEDs 20 to 25 and the correction of the wavelength variation of each LED 20 to 25 (a phenomenon in which the peak wavelength of the LED light shifts to the long wavelength side or the short wavelength side). A combined table obtained by combining two types of tables with the control signal correction table is stored. This combination table is sequentially read from the memory 31 shown in FIG. 7 for each observation mode.

  In the normal observation mode, the normal observation B1 dimming table 32a, G1 dimming table 33a, R1 dimming table 34a, SA1 dimming table 35a, SB1 dimming table 36a, B control signal correction table 39, G control signal The combined tables TB1, TG1, TR1, TSA1, and TSB1 are read out by combining the correction table 40, the R control signal correction table 41, the SA control signal correction table 42, and the SB control signal correction table 43. These combination tables TB1, TG1, TR1, TSA1, and TSB1 are stored in the B-LUT 32, the G-LUT 33, the R-LUT 34, the first special light LUT 35, and the second special light LUT 36, respectively.

  The B1 dimming table 32a stores the relationship between the brightness instruction signal n and the light source control signal applied to the B-LED 20 when the brightness instruction signal n is used. Similarly to the B1 dimming table 32a, the G1 dimming table, R1 dimming table, SA1 dimming table, and SB1 dimming table 33a to 36a are also provided with brightness instruction signals n and light source control signals applied to the LEDs 21 to 24, respectively. I remember the relationship.

  In each of the dimming tables 32a to 36a, between the RGB image signals obtained by irradiating the white subject portion WST in the integrating sphere ST with light emitted by driving the LEDs 20 to 24 and imaging the white subject portion WST. The relationship between the light source control signal of each LED 20 to 24 and the brightness instruction signal n is stored so that the signal ratio maintains the set signal ratio r1: g1: b1 for any brightness instruction signal n. ing. Accordingly, when the LEDs 20 to 24 are controlled to emit light based on the dimming tables 32a to 36a, and the observation target is imaged based on the light emitted from the LEDs 20 to 24, what brightness instruction signal n is used. Even in such a case, the white portion to be observed can be displayed in white in the image (that is, the white balance is maintained regardless of the brightness instruction signal). In the normal observation mode, since the RGB image signal is assigned to the RGB video channel of the monitor, the white portion to be observed is displayed in white in the image.

The B control signal correction table 39, the G control signal correction table 40, the R control signal correction table 41, the SA control signal correction table 42, and the SB control signal correction table 43 correspond to the light source control signal and the light source control signal. A light amount linear light source control signal for linearly increasing or decreasing the light amount of the LEDs 20 to 24 is stored in association with each other. In B the control signal correction table 39, as shown in FIG. 8, a relationship when the light source control signal is a constant value P ^* less, relationship and are different in the case of the light source control signal exceeds a predetermined value P ^*.

The relationship shown in FIG. 8 is set for the following reason. When the light source control signal is equal to or less than a certain value P ^* , that is, when the light emission intensity of each LED 20 is small, the wavelength variation does not occur in each LED 20, so the light amount of each LED 20 increases or decreases linearly. On the other hand, when the light source control signal exceeds a certain value P ^*, that is, when the light emission intensity of each LED 20 is large, the wavelength variation occurs in each LED 20, so that the light quantity of each LED 20 does not increase or decrease linearly. Therefore, when the light source control signal exceeds a certain value P ^* , the relationship between the light source control signal and the light source linear light source control signal is made different from that in the case where the light source control signal is equal to or less than the certain value P ^*. The amount of light increases and decreases linearly. Note that the control signal correction tables 40 to 43 have a relationship as shown in FIG.

  In the normal observation mode, when the brightness instruction signal n is input to each of the LUTs 32 to 36, the light source control signal n corresponding to the input brightness instruction signal n is referred to the dimming tables 32a to 36a. Selected. Then, referring to the control signal correction tables 39 to 43, the light source control signal n for the light amount linear corresponding to the selected light source control signal n is selected. Based on this light amount linear light source control signal n, the LEDs 20 to 24 emit blue light B, green light G, red light R, first special light SA, and second special light SB.

  The LUTs 32 to 36 store combined tables TB1, TG1, TR1, TSA1, and TSB1 in which the dimming tables 32a to 36a and the control signal correction tables 39 to 43 are combined. The light source control signal n for linear light quantity is directly output in response to the input of the signal n.

  In the first special light observation mode, the G2 dimming table 33b, SA2 dimming table 35b, SB2 dimming table 36b for the first special light observation mode, G control signal correction table 40, SA control signal correction table 42, SB Combination tables TG 2, TSA 2, and TSB 2 combined with the control signal correction table 43 are read from the memory 31. These combination tables TG2, TSA2, and TSB2 are stored in the G-LUT 33, the first special light LUT 35, and the second special light LUT 36, respectively.

  The G2 dimming table 33b stores the relationship between the brightness instruction signal n and the light source control signal applied to the G-LED 21 when the brightness instruction signal n is used. Similarly to the G2 dimming table 33b, the SA2 dimming table 35b and the SB2 dimming table 36b also store the relationship between the brightness instruction signal n and the light source control signal applied to the LEDs 23 and 24. On the other hand, the control signal correction tables 40, 42, and 43 are the same as the tables stored in the LUTs 33, 35, and 36 in the normal observation mode.

  In each of the dimming tables 33b, 35b, and 36b, RGB obtained by irradiating the white subject portion WST in the integrating sphere ST with light emitted by driving the LEDs 21, 23, and 24, and imaging the white subject portion WST. The light source control signal of each LED 21, 23, and 24 and the brightness instruction signal n so that the signal ratio between the image signals maintains the set signal ratio g2: b2 for any brightness instruction signal n. I remember the relationship. Accordingly, when the LEDs 21, 23, and 24 are controlled to emit light based on the dimming tables 33b, 35b, and 36b, and the observation target is imaged based on the light emitted from the LEDs 21, 23, and 24, what kind of Even with the brightness instruction signal n, the white portion to be observed can be displayed in a predetermined reference color in the image (that is, the color balance is maintained with any brightness instruction signal). ) In the first special light observation mode, the pseudo color is displayed based on the B image signal and the G image signal, so that the white portion to be observed is displayed with a predetermined reference color in the image.

  In the second special light observation mode, the G3 dimming table 33c, the R3 dimming table 34c, the SA3 dimming table 35c, the SB3 dimming table 36c for the second special light observation mode, the control G control signal correction table 40, R A combination table TG3, TR3, TSA3, and TSB3, which is a combination of the control signal correction table 41, the SA control signal correction table 42, and the SB control signal correction table 43, is read from the memory 31. These combination tables TG3, TR3, TSA3, and TSB3 are stored in the G-LUT 33, the R-LUT 34, the first special light LUT 35, and the second special light LUT 36, respectively.

  The G3 dimming table 33c stores the relationship between the brightness instruction signal n and the light source control signal applied to the G-LED 21 when the brightness instruction signal n is used. Similarly to the G3 dimming table 33c, the R3 dimming table 34c, the SA3 dimming table 35c, and the SB3 dimming table 36c store the relationship between the brightness instruction signal n and the light source control signal applied to each of the LEDs 22-24. ing. On the other hand, the control signal correction tables 40, 41, 42, 43 are the same as the tables stored in the LUTs 33, 34, 35, 36 in the normal observation mode.

  In each of the dimming tables 33c to 36c, between the RGB image signals obtained by irradiating the white subject portion WST in the integrating sphere ST with the light emitted by driving the LEDs 21 to 24 and imaging the white subject portion WST. The relationship between the light source control signal of each LED 21 to 24 and the brightness instruction signal n is stored so that the signal ratio maintains the set signal ratio r3: g3: b3 for any brightness instruction signal n. ing. Accordingly, when the LEDs 21 to 24 are controlled to emit light based on the dimming tables 33c to 36c, and the observation target is imaged based on the light emitted from the LEDs 21 to 24, what brightness instruction signal n is used. Even in such a case, the white portion to be observed can be displayed in a predetermined reference color in the image (that is, the color balance is maintained regardless of the brightness instruction signal). In the second special light observation mode, the image is displayed in a pseudo color based on the RGB image signal, so that the white portion to be observed is displayed in a predetermined reference color in the image.

  In the third special light observation mode, a combination table TSB4 combining the SB4 light adjustment table 36d and the SC4 light adjustment table 37d for the third special light observation mode, the SB control signal correction table 43, and the SC control signal correction table 44, TSC4 is read from the memory 31. The combination tables TSB4 and TSC4 are stored in the second special light LUT 36 and the third special light LUT 37, respectively.

  The SB4 dimming table 36d stores the relationship between the brightness instruction signal n and the light source control signal applied to the second special light LED 24 at the time of the brightness instruction signal n. Similarly to the SB4 dimming table 36d, the SC4 dimming table 37d also stores the relationship between the brightness instruction signal n and the light source control signal applied to the third special light LED 25.

  In each dimming table 36d, 37d, between the RGB image signals obtained by irradiating the white subject portion WST in the integrating sphere ST with the light emitted by driving the LEDs 24, 25 and imaging the white subject portion WST. The relationship between the light source control signal of each LED 24 and 25 and the brightness instruction signal n is stored so that the signal ratio maintains the set signal ratio g4: b4 for any brightness instruction signal n. . Accordingly, when the LEDs 24 and 25 are controlled to emit light based on the dimming tables 36d and 37d and the observation target is imaged based on the light emitted from the LEDs 24 and 25, what brightness instruction signal n is used. Even in such a case, the white portion to be observed can be displayed in a predetermined reference color in the image (that is, the color balance is maintained regardless of the brightness instruction signal). In the third special light observation mode, an image is displayed in a pseudo color based on the B image signal and the G image signal, so that the white portion to be observed is displayed in a predetermined reference color in the image.

On the other hand, the control signal correction table 43 is the same as the table stored in the LUT 36 in the normal observation mode. The control signal correction table 44 is the same as the control signal correction tables 39 to 43, and the relationship between the light source control signal and the light source control signal for the light amount linear when the light source control signal is equal to or less than a certain value P ^*, and the light source control. The relationship between the light source control signal and the light amount linear light source control signal when the signal exceeds a certain value P ^* is different.

  As shown in FIG. 6, the calibration circuit 30 includes a calibration unit 45, a dimming table creation unit 46, a light amount linear light control unit 47, and a color chart equivalent color light control unit 48. The calibration unit 45 includes a calibration light emission control unit 45a and a specific light source control signal setting unit 45b.

  The calibration unit 45 performs processing according to a calibration sequence determined for each observation mode. In the calibration sequence for the normal observation mode, the calibration light emission control unit 45a is controlled so that the five LEDs B-LED 20, G-LED 21, R-LED 22, first special light LED 23, and second special light LED 24 are displayed. At the same time, the integrating sphere ST is irradiated with blue light, green light, red light, first special light, and second special light emitted from each LED. The integrating sphere ST irradiated with these five colors of light is imaged by the imaging sensor 51c, and RGB image signals are output from the imaging sensor 51c by this imaging.

  The light source control signals VB [m], VG [m], VR [m], VSA [m], and VSB [m] to be applied to the LEDs 20 to 24 are expressed as “M / 2 (half the maximum number of bits)” and “ "M (maximum number of bits)", the number of bits is changed to change the emission intensity and time of blue light, green light, red light, first special light, and second special light emitted from each LED. . The imaging sensor 51c captures the integrating sphere ST and outputs an RGB image signal every time the number of bits of the light source control signal changes. The number of bits may be changed from “0” instead of changing the number of bits from “M / 2 (half the maximum number of bits)”.

The specific light source control signal setting unit 45b determines whether or not the signal ratio between the RGB image signals output from the imaging sensor 51c matches the normal observation mode setting signal ratio r1: g1: b1. If the set signal ratio r1: g1: b1 is met, the light source control signals VB1 ^* , VG1 ^* , VR1 ^* , VSA1 ^* , VSB1 ^* applied to the LEDs 20 to 24 at that time are set as specific light source control signals. On the other hand, when the set signal ratio r1: g1: b1 for the normal observation mode does not match, the light source control signal applied to the LEDs 20 to 24 at that time is not used as the specific light source control signal.

  In the calibration sequence for the first special light observation mode, the calibration light emission control unit 45a is controlled so that the three LEDs G-LED 21, first special light LED 23, and second special light LED 24 are turned on simultaneously. The integrating sphere ST is irradiated with green light, first special light, and second special light emitted from the LED. The integrating sphere ST irradiated with these three colors of light is imaged by the image sensor 51c, and an RGB image signal is output from the image sensor 51c by this imaging. As in the calibration sequence for the normal observation mode, the image sensor 51c is changed while changing the number of bits of the light source control signals VG [m], VSA [m], and VSB [m] applied to the LEDs 21, 23, and 24. Then, the integrating sphere ST is imaged.

In the specific light source control signal setting unit 45b, the signal ratio between the B image signal and the G image signal among the RGB image signals output from the imaging sensor 51c matches the setting signal ratio b2: g2 for the first special light observation mode. It is determined whether or not to do. If the set signal ratio b2: g2 is met, the light source control signals VG2 ^* , VSA2 ^* , VSB2 ^{* applied} to the LEDs 21, 23, 24 at that time are set as specific light source control signals. On the other hand, when it does not coincide with the setting signal ratio g2: b2 for the first special light observation mode, the light source control signal applied to the LEDs 21, 23, 24 at that time is not used as the specific light source control signal.

  In the calibration sequence for the second special light observation mode, the calibration light emission control unit 45a is controlled so that four LEDs of G-LED 21, R-LED 22, first special light LED 23, and second special light LED 24 are simultaneously provided. The integrating sphere ST is irradiated with green light, red light, first special light, and second special light emitted from each LED. The integrating sphere ST irradiated with these four colors of light is imaged by the imaging sensor 51c, and RGB image signals are output from the imaging sensor 51c by this imaging. Then, as with the calibration sequence for the normal observation mode, while changing the number of bits of the light source control signals VG [m], VR [m], VSA [m], and VSB [m] applied to the LEDs 21 to 24, Imaging of the integrating sphere ST is performed by the imaging sensor 51c.

The specific light source control signal setting unit 45b determines whether or not the signal ratio between the RGB image signals output from the imaging sensor 51c matches the setting signal ratio r3: g3: b3 for the second special light observation mode. . When the set signal ratio r3: g3: b3 is met, the light source control signals VG3 ^* , VR3 ^* , VSA3 ^* , VSB3 ^* applied to the LEDs 21 to 24 at that time are set as specific light source control signals. On the other hand, when it does not coincide with the setting signal ratio r3: g3: b3 for the second special light observation mode, the light source control signal applied to the LEDs 21 to 24 at that time is not used as the specific light source control signal.

  In the calibration sequence for the third special light observation mode, the calibration light emission control unit 45a is controlled to turn on the two LEDs of the second special light LED 24 and the third special light LED 25 at the same time. The second special light and the third special light are irradiated to the integrating sphere ST. The integrating sphere ST irradiated with these two colors of light is imaged by the imaging sensor 51c, and RGB image signals are output from the imaging sensor 51c by this imaging. As in the calibration sequence for the normal observation mode, the image sensor 51c captures the image of the integrating sphere ST while changing the number of bits of the light source control signals VSB [m] and VSC [m] applied to the LEDs 24 and 25. Do.

In the specific light source control signal setting unit 45b, the signal ratio between the B image signal and the G image signal among the RGB image signals output from the imaging sensor 51c matches the setting signal ratio b4: g4 for the third special light observation mode. It is determined whether or not to do. When the set signal ratio b4: g4 is matched, the light source control signals VSB4 ^* and VSC4 ^* applied to the LEDs 24 and 25 at that time are set as specific light source control signals. On the other hand, if the setting signal ratio g4: b4 for the third special light observation mode does not coincide, the light source control signal applied to the LEDs 24 and 25 at that time is not used as the specific light source control signal.

The dimming table creation unit 46 includes a reference light source control signal setting unit 46a, a control signal ratio calculation unit 46b, a light source control signal setting unit 46c for brightness step n, and an association unit 46d for dimming table creation. doing. The dimming table creation unit 46 performs processing according to a table creation sequence determined for each observation mode. In the table creation sequence for the normal observation mode, first, the reference light source control signal setting unit 46a compares the number of bits of the specific light source control signals VB1 ^* , VG1 ^* , VR1 ^* , VSA1 ^* , VSB1 ^* , respectively. Identify the big one. Here, assuming that the specific light source control signal VB1 ^* is the largest, the light source control signal VB [m] of the B-LED 20 is set as the reference light source control signal. Next, the control signal ratio calculation unit 46b obtains the control signal ratios VG1 ^* / VB1 ^* and VR1 ^* / VB1 ^* between the specific light source control signal VB1 ^* and the specific light source control signals VG1 ^* and VR1 ^* .

Next, the brightness step n light source control signal setting unit 46c divides the maximum number of bits VBmax of the light source control signal VB [m] of the B-LED 20 that is the reference light source control signal into N parts to obtain the brightness of the B-LED 20 The light source control signal VB1 [n] for step n is set (VB1 [n] = n × VBmax / (N−1)). Next, as shown in FIG. 9, the brightness step n light source control signal VB1 [n] is multiplied by the control signal ratio VR1 ^* / VB1 ^* , and the R-LED 22 brightness step n light source control signal VR1. [N] is obtained. Further, the brightness step n light source control signal VB1 [n] is multiplied by the control signal ratio VG1 ^* / VB1 ^* to obtain the brightness step n light source control signal VG1 [n] of the G-LED 21.

  Further, the brightness step n light source control signal VB1 [n] is multiplied by W1 (a number between 0 and 100%) to obtain the brightness step n light source control signal VSA1 [n] of the first special light LED 23. Ask for. Further, the brightness step n light source control signal VB1 [n] is multiplied by W2 (a number between 0 and 100%) to obtain the brightness step n light source control signal VSB1 [n] of the second special light LED 24. Ask for.

  The dimming table creating association unit 46d associates the brightness step n light source control signal VB1 [n] set by the brightness step n light source control signal setting unit 46c with the brightness instruction signal n, A B1 dimming table is created. Similarly to the B1 dimming table, the brightness step n light source control signals VG1 [n], VR1 [n], VSA1 [n], VSB1 [n] and the brightness instruction signal n are associated with each other. , G1 dimming table, R1 dimming table, SA1 dimming table, and SB1 dimming table are created. When the light quantity control of each of the LEDs 20 to 24 is performed based on these five dimming tables, the white balance can be optimally maintained for any brightness instruction signal n.

Table creation sequence for the first special light observation mode, first, the reference light source control signal setting unit 46a, a particular light source control signal ^{VG2 *,} VSA2 ^*, compared VSB2 ^* number of bits, respectively, those largest Identify. Here, if the specific light source control signal VSA2 ^* is the largest, the light source control signal VSA [m] of the first special light LED 23 is set as the reference light source control signal. Next, the control signal ratio calculation unit 46b obtains the control signal ratio VG2 ^* / VSA2 ^* between the specific light source control signal VSA2 ^* and the specific light source control signal VG2 ^* .

Next, the light source control signal setting unit 46c for the brightness step n divides the maximum bit number VSAmax of the light source control signal VSA [m] of the first special light LED 23, which is the reference light source control signal, into N parts to obtain the first special light source control signal. The light source control signal VSA2 [n] for the brightness step n of the light LED 23 is set (VSA2 [n] = n × VSAmax / (N−1)). Next, as shown in FIG. 10, the brightness step n light source control signal VSA2 [n] is multiplied by the control signal ratio VG2 ^* / VSA2 ^* to obtain the brightness step n light source control signal VG2 of the G-LED 21. [N] is obtained. Further, the brightness step n light source control signal VSA2 [n] is multiplied by T1 (a number between 0 and 100%) to obtain the brightness step n light source control signal VSB2 [n] of the second special light LED 24. Ask for.

  The dimming table creation association unit 46d associates the brightness step n light source control signal VG2 [n] set by the brightness step n light source control signal setting unit 46c with the brightness instruction signal n, A G2 dimming table is created. Similarly to the G2 dimming table, the brightness step n light source control signals VSA2 [n], VSB2 [n] and the brightness instruction signal n are associated with each other, thereby the SA2 dimming table and the SB2 dimming table. Create When the light quantity control of each LED 21, 23, 24 is performed based on these three dimming tables, the color balance can be kept optimal for any brightness instruction signal n.

In the table creation sequence for the second special light observation mode, first, the reference light source control signal setting unit 46a compares the number of bits of the specific light source control signals VG3 ^* , VR3 ^* , VSA3 ^* , VSB3 ^* , respectively. Identify the big one. Here, if the specific light source control signal VSA3 ^* is the largest, the light source control signal VSA [m] of the first special light LED 23 is set as the reference light source control signal. Further, the control signal ratio calculation unit 46b obtains the control signal ratios VG3 ^* / VSA3 ^* and VR3 ^* / VSA3 ^* between the specific light source control signal VSA3 ^* and the specific light source control signals VG3 ^* and VR3 ^* .

Next, the light source control signal setting unit 46c for the brightness step n divides the maximum bit number VSAmax of the light source control signal VSA [m] of the first special light LED 23, which is the reference light source control signal, into N parts to obtain the first special light source control signal. The light source control signal VSA3 [n] for the brightness step n of the light LED 23 is set (VSA3 [n] = n × VSAmax / (N−1)). Next, as shown in FIG. 11, the brightness step n light source control signal VSA3 [n] is multiplied by the control signal ratio VR3 ^* / VSA3 ^* to obtain the brightness step n light source control signal VR3 of the R-LED 22. [N] is obtained. Further, the brightness step n light source control signal VSA3 [n] is multiplied by the control signal ratio VG3 ^* / VSA3 ^* to obtain the brightness step n light source control signal VG3 [n] of the G-LED 21. Further, the brightness step n light source control signal VSA3 [n] is multiplied by T2 (a number between 0 and 100%) to obtain the brightness step n light source control signal VSB3 [n] of the second special light LED 24. Ask for.

  The dimming table creation association unit 46d associates the brightness step n light source control signal VG3 [n] set by the brightness step n light source control signal setting unit 46c with the brightness instruction signal n, Create a G3 dimming table. Similarly to the G3 dimming table, the brightness step n light source control signals VR3 [n], VSA3 [n], VSB3 [n] and the brightness instruction signal n are associated with each other to thereby match the R3 dimming table. , SA3 dimming table and SB3 dimming table are created. When the light quantity control of each of the LEDs 21 to 24 is performed based on these four dimming tables, the color balance can be optimally maintained for any brightness instruction signal n.

In the table creation sequence for the third special light observation mode, first, the reference light source control signal setting unit 46a compares the number of bits of the specific light source control signals VSB4 ^* and VSC4 ^* to identify the largest one. Here, if the specific light source control signal VSC4 ^* is larger, the light source control signal VSC [m] of the third special light LED 25 is set as the reference light source control signal. Further, the control signal ratio calculation unit 46b obtains a control signal ratio VSB4 ^* / VSC4 ^* between the reference light source control signal VSC4 ^* and the specific light source control signal VSB4 ^* .

Next, the brightness step n light source control signal setting unit 46c divides the maximum number of bits VSCmax of the light source control signal VSC [m] of the third special light LED 25, which is the reference light source control signal, into N parts to obtain the third special light source control signal. The light source control signal VSC4 [n] for the brightness step n of the light LED 23 is set (VSC4 [n] = n × VSCmax / (N−1)). Next, as shown in FIG. 12, the brightness step n light source control signal VSA4 [n] is multiplied by the control signal ratio VSB4 ^* / VSC4 ^* to obtain the brightness step n light source of the second special light LED 24. The control signal VSB4 [n] is obtained.

  The dimming table creation association unit 46d associates the brightness step n light source control signal VSB4 [n] set by the brightness step n light source control signal setting unit 46c with the brightness instruction signal n, An SB4 dimming table is created. Similarly to this SB4 dimming table, the SC4 dimming table is created by associating the light source control signal VSC4 [n] for the brightness step n with the brightness instruction signal n. When the light quantity control of each LED 24, 25 is performed based on these two dimming tables, the color balance can be kept optimal for any brightness instruction signal n.

  The light amount linear light control unit 47 controls the light emission of each of the LEDs 20 to 25 based on a combined table obtained by combining the light control table and the control signal correction table used in each observation mode, and generates the brightness instruction signal n. On the other hand, light amount linear light whose light amount changes linearly is emitted. The light quantity linear light control unit 47 increases the brightness instruction signal n bit by bit from “1” of the minimum bit to “N” of the maximum bit, and increases the number of bits of the brightness instruction signal n. Next, the LEDs 20 to 25 are driven by the light source control signal corresponding to the brightness instruction signal n with reference to the combination table. Thereby, light quantity linear light whose light quantity changes linearly is emitted in a state where white balance or color balance is maintained. Each time the light quantity is changed by increasing the number of bits of the brightness instruction signal n, the imaging sensor 51c performs imaging in the integrating sphere, and the brightness instruction signal n is converted into a luminance linear table creation unit 61 in the processor device. Send to.

  When the LEDs 20 to 24 are driven based on the coupling tables TB1, TG1, TR1, TSA1, and TSB1 used in the normal observation mode, blue light, green light, red light, first special light, and second special light are mixed. First light amount linear light is emitted. The first light amount linear light changes linearly in a state where white balance is maintained in accordance with the change of the brightness instruction signal n. When the LEDs 21, 23, 24 are driven based on the coupling tables TG2, TSA2, TSB2 used in the first special light observation mode, the second light quantity linear light in which the green light, the first special light, and the second special light are mixed. Is emitted. The second light amount linear light linearly changes in light amount while maintaining the color balance in accordance with the change in the brightness instruction signal n.

  When the LEDs 21 to 24 are driven based on the coupling tables TG3, TR3, TSA3, and TSB3 used in the third special light observation mode, the third color in which the green light, the red light, the first special light, and the second special light are mixed. Light amount linear light is emitted. The light amount of the third light amount linear light linearly changes in accordance with the change of the brightness instruction signal n while maintaining the color balance. When the LEDs 24 and 25 are driven based on the coupling tables TSB4 and TSC4 used in the fourth special light observation mode, the fourth light quantity linear light in which the second special light and the third special light are mixed is emitted. In the fourth light amount linear light, the light amount changes linearly in a state where the color balance is maintained in accordance with the change in the brightness instruction signal n.

  The color chart equivalent color light control unit 48 emits illumination light used in each observation mode among blue light, green light, red light, first illumination light, second illumination light, and third illumination light at a predetermined light amount ratio. In this way, by controlling the LEDs 20 to 25, light of a color corresponding to the color of the color chart (color chart equivalent color light) is generated. As shown in FIG. 13, the color chart equivalent color light is irradiated to the white subject portion WST in the integrating sphere ST. The portion illuminated with the color chart equivalent color light in the white subject part WST is illuminated with the color corresponding to the color chart.

  The white subject portion WST illuminated with the color chart equivalent color light is imaged by the imaging sensor 51c, and a color for matching the color of the endoscopic image to the target color based on the image signal obtained by the imaging and the target image signal. Set conditions for correction processing. In this embodiment, matrix coefficients for matrix calculation, which is one of color correction processes, are set. From the above, it is possible to set conditions for color correction processing (setting matrix coefficients) using only a white reference subject such as the white subject portion WST without using a color chart.

  The color chart equivalent color light control unit 48 can emit a plurality of color chart equivalent color lights, and the relationship between the color chart equivalent color light and the light quantity ratios of the LEDs 20 to 25 corresponds to the light quantity ratio for each observation mode. Pre-stored in table 48a. The relationship between each color chart equivalent color light and the light quantity ratio of each LED 20-25 is defined as follows. In the case of color light equivalent to the color chart for the normal observation mode, blue light and green light with a predetermined brightness step n amount based on the combined table TB1, TG1, TR1, TSA1, and TSB1 created as described above. , Red light, first special light, and second special light are emitted. Since the emitted five colors of light are light generated based on the coupling tables TB1, TG1, TR1, TSA1, and TSB1, white balance is maintained. Then, the emitted five colors of light are applied to the color chart shown in FIG. 14, and imaging is performed by the endoscope 12 including the imaging sensor 51 c having typical spectral sensitivity characteristics (average spectral sensitivity characteristics). Thereby, an Rc image signal, a Gc image signal, and a Bc image signal are obtained.

  Next, from the Rc image signal, the Gc image signal, and the Bc image signal obtained at the time of color chart imaging, the light quantity ratio of the LEDs 20 to 24 necessary for generating color chart equivalent color light is calculated. Since the spectral radiation characteristics of the LEDs 20 to 24 and the spectral sensitivity of the image sensor 51c are known, the white object portion WST is imaged at a predetermined light intensity ratio of blue light, green light, red light, first special light, and second special light. The RGB image signal obtained at this time is also known. Therefore, it is possible to create a table between the light amount ratio and the image signal indicating the relationship between the light amount ratio between the LEDs 20 to 24 and the RGB image signal obtained when the white object portion WST is imaged with this light amount ratio. . With reference to this light quantity ratio-image signal table, the light quantity ratio corresponding to the Rc image signal, Gc image signal, and Bc image signal obtained at the time of color chart imaging is obtained. The obtained light quantity ratio is the light quantity ratio of the LEDs 20 to 24 necessary for generating the color chart equivalent color light.

  The relationship between the color chart equivalent color light for the first special light observation mode and the light quantity ratio of the LEDs 21, 23, 24, the relationship between the color chart equivalent color light for the second special light observation mode and the light quantity ratio of the LEDs 20 to 24, The relationship between the color chart equivalent color light for the third special light observation mode and the LEDs 24 and 25 can be determined similarly to the color chart equivalent color light for the normal observation mode.

  As shown in FIG. 2, the distal end portion 12 d of the endoscope 12 has an illumination optical system 50 and an imaging optical system 51. The illumination optical system 50 has an illumination lens 50a, and light from the light guide 49 is irradiated to the observation object through the illumination lens 50a. The imaging optical system 51 includes an imaging lens 51a, a zoom lens 51b, and an imaging sensor 51c. The reflected light from the observation target enters the image sensor 51c via the image pickup lens 51a and the zoom lens 51b. As a result, a reflected image of the observation target is formed on the image sensor 51c.

  The image sensor 51c is a color image sensor, which captures a reflected image of an observation target and outputs an image signal. The imaging sensor 51c is preferably a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) image sensor, or the like. The image sensor used in the present invention is a color image sensor for obtaining image signals of three colors R (red), G (green), and B (blue), that is, so-called RGB having an RGB filter on the imaging surface. It is an image sensor. Here, a pixel provided with an R filter is referred to as an R pixel, a pixel provided with a G filter is referred to as a G pixel, and a pixel provided with a B filter is referred to as a B pixel.

  The image sensor 51c may be a so-called complementary color image sensor including color filters of C (cyan), M (magenta), Y (yellow), and G (green) instead of the RGB image sensor. . In the case of a complementary color image sensor, RGB three-color image signals can be obtained by color conversion from four CMYG image signals. In this case, it is necessary to provide either the endoscope 12 or the processor device 16 with means for performing color conversion from the CMYG four-color image signal to the RGB three-color image signal.

  The image signal output from the image sensor 51 c is transmitted to the CDS / AGC circuit 52. The CDS / AGC circuit 52 performs correlated double sampling (CDS) and automatic gain control (AGC) on an image signal that is an analog signal. The image signal that has passed through the CDS / AGC circuit 52 is converted into a digital image signal by an A / D converter (A / D converter) 53. The A / D converted digital image signal is input to the processor device 16.

  The processor device 16 includes a reception unit 54, a light amount calculation unit 55, a DSP 56, a noise removal unit 58, a brightness instruction signal generation unit 59, an image processing switching unit 60, a normal image processing unit 62, and a first image processing unit 62. A special light image processing unit 63, a second special light image processing unit 64, a third special light image processing unit 65, and a video signal generation unit 66 are provided. The receiving unit 54 receives digital RGB image signals from the endoscope 12. The received RGB image signal is transmitted to the light amount calculation unit 55 and also to the calibration circuit 30 in the light source control unit 27. The light amount calculation unit 55 calculates the light amount of each illumination light based on the digital image signal received by the reception unit 54. The calculated light amount is sent to the brightness instruction signal generation unit 59.

  The brightness instruction signal generation unit calculates a target light amount based on the light amount calculated by the light amount calculation unit 55, and generates a brightness instruction signal n based on the calculated target light amount. In the brightness instruction signal, the target light quantity increases as the number of bits increases. The generated brightness instruction signal n is sent to the observation mode circuit 29 of the light source device.

  The DSP 56 performs gamma correction and color correction processing on the image signal received by the receiving unit 54. The noise removing unit 58 removes noise from the image signal by performing noise removal processing (for example, a moving average method, a median filter method, etc.) on the image signal subjected to gamma correction or the like by the DSP 56. The image signal from which noise has been removed is transmitted to the image processing switching unit 60.

  The image processing switching unit 60 transmits the RGB image signal to the normal image processing unit 62 when the mode switching SW 13a is set to the normal observation mode, and when it is set to the first special light observation mode. Transmits the RGB image signal to the first special light image processing unit 63, and when the second special light observation mode is set, transmits the RGB image signal to the second special light image processing unit 64, If the 3 special light observation mode is set, the RGB image signal is transmitted to the third special light image processing unit 65. When the calibration mode is set, the RGB image signal is converted from the luminance linear table creation unit 61, the normal image processing unit 62, the first special light image processing unit 63, the second special light image processing unit 64, the first 3 is transmitted to the special light image processing unit 65.

  The luminance linear table creation unit 61 includes a luminance linear signal generation unit 61a and a luminance linear table creation association unit 61b. The luminance linear signal generation unit 61a is based on the RGB image signal obtained when the light amount linear light is emitted and the brightness instruction signal n transmitted from the light amount linear light control unit 47 when the light amount linear light is emitted. A luminance linear RGB image signal in which the signal value of the RGB image signal changes linearly with respect to the brightness instruction signal n is generated. The luminance linear table creation associating unit 61b creates a luminance linear table by associating the RGB image signal with the luminance linear RGB image signal.

  The luminance linear table includes a normal observation mode luminance linear table LNT1, a first special light observation mode luminance linear table LNT2, a second special light observation mode luminance linear table LNT3, and a third special light observation mode luminance linear table LNT4. There are four. The luminance linear table LNT1 for normal observation mode stores an RGB image signal obtained when the first light amount linear light is emitted and a luminance linear RGB image signal obtained by the luminance linear signal generation unit 61a when the light is emitted. The luminance linear table LNT2 for the first special light observation mode associates and stores the RGB image signal obtained when the second light amount linear light is emitted and the luminance linear RGB image signal obtained by the luminance linear signal generation unit 61a when the light is emitted. ing.

  The luminance linear table LNT3 for the second special light observation mode associates and stores the RGB image signal obtained when the third light amount linear light is emitted and the luminance linear RGB image signal obtained by the luminance linear signal generation unit 61a during the emission. ing. The luminance linear table LNT4 for the third special light observation mode associates and stores the RGB image signal obtained at the time of the fourth light amount linear light emission and the luminance linear RGB image signal obtained by the luminance linear signal generation unit 61a at the time of this light emission. ing. These luminance linear tables are stored in luminance linear conversion units in the normal image processing unit 62, the first special light image processing unit 63, the second special light image processing unit 64, and the third special light image processing unit 65.

  The normal image processing unit 62 generates a normal image in which the observation target is expressed in a normal biological color tone. As shown in FIG. 15, the normal image processing unit 62 includes a luminance linear conversion unit 62a that converts the RGB image signal into a signal whose signal value changes linearly with respect to the brightness instruction signal n, and a luminance linear conversion unit A color correction processing unit 62b that performs color correction processing on the RGB image signal, a gradation conversion processing unit 62c that performs gradation conversion processing on the color-corrected image signal, and a tone-converted image signal A color enhancement processing unit 62d that performs various color enhancement processing and a structure enhancement unit 62e that performs structure enhancement processing such as sharpness and contour enhancement on the color enhancement processed image signal.

  The luminance linear conversion unit 62a includes a normal observation luminance linear table LNT1. In the luminance linear conversion unit 62a, the luminance linear RGB image signal corresponding to the RGB image signal is specified with reference to the normal observation luminance linear table LNT1. The luminance linear RGB image signal is sent to the color correction processing unit 62b.

式（１）において「Ｒ、Ｇ、Ｂ」はＲＧＢ画像信号を示しており、「Ｒ´、Ｇ´、Ｂ´」は色補正済みのＲＧＢ画像信号を示しており、「ｋ１１〜ｋ３３」はマトリックス係数を示している。この色補正済みのＲＧＢ画像信号に基づいて画像表示を行うことにより、ユーザーが予め設定した色である目標色を画像上で表示することが可能となる。The color correction processing unit 62 b includes a matrix calculation unit 67 and a matrix coefficient setting unit 68. The matrix calculation unit 67 corrects the color of the luminance linear RGB image signal by matrix calculation represented by the following formula (1). Thereby, a color-corrected RGB image signal is obtained.

In Expression (1), “R, G, B” indicates an RGB image signal, “R ′, G ′, B ′” indicates a color-corrected RGB image signal, and “k11 to k33” are The matrix coefficient is shown. By performing image display based on the color-corrected RGB image signal, it is possible to display a target color, which is a color preset by the user, on the image.

  The matrix coefficient setting unit 68 sets matrix coefficients k11 to k33 in the calibration mode. The matrix coefficient setting unit 68 sets the matrix coefficients k11 to k33 so that the image signal (RGB image signal) obtained when the color chart equivalent color light is emitted becomes the target image signal (RGB image signal). To do. As described above, by setting the matrix coefficient in the calibration mode, even if the endoscope 12 is replaced and the spectral sensitivity of the imaging sensor 51c of the endoscope 12 is changed, the endoscope 12 after the replacement is changed. An appropriate matrix coefficient can be set. Thereby, even if the endoscope 12 is replaced, the color on the image can be matched with the target color.

  The relationship between the color chart equivalent color light and the target RGB image signal is stored in advance in a table (not shown) in the matrix coefficient setting unit 68. The target RGB image signal is generated in advance by a target signal generation unit (not shown) in the processor device 16. The target signal generation unit generates a target RGB image signal based on target color data input by the user via the console 19.

  The first special light image processing unit 63 generates a first special light image in which blood vessels on the observation target are emphasized. The second special light image processing unit 64 generates a second special light image that emphasizes blood vessels on the observation target and secures the same brightness as that of the normal image. The third special light image processing unit 65 generates a third special light image that is a pseudo color image of the oxygen saturation of blood hemoglobin to be observed. The images generated by these image processing units 62 to 65 are sent to the video signal generation unit 66.

  Although not shown in the drawing, the first special light image processing unit 63, the second special light image processing unit 64, and the third special light image processing unit 65 are each provided with a linear luminance as in the normal image processing unit 62. A conversion unit, a color correction processing unit, a gradation conversion processing unit, a color enhancement processing unit, and a structure enhancement unit are provided. Each luminance linear conversion unit includes a luminance linear signal generation unit and an association unit as in the luminance linear conversion unit 62a, and the color correction processing unit, like the color correction processing unit 62b, is a matrix calculation unit. And a matrix coefficient setting unit.

  The video signal generation unit 66 converts the image input from each of the image processing units 62 to 65 into a video signal for display on the monitor 18 as a displayable image. Based on this converted video signal, the monitor 18 displays a normal image in the normal observation mode, displays a first special light image in the first special light observation mode, and displays a second special light in the second special light observation mode. A light image is displayed, and the third special light image is displayed in the third special light observation mode.

  Next, the calibration method of the present invention will be described with reference to the flowchart of FIG. First, the light source device 14 and the processor device 16 are turned on. Then, the endoscope 12 is attached to the light source device 14 and the processor device 16. Then, the distal end portion 12d of the endoscope 12 is inserted into the integrating sphere ST that is a reference subject. The mode switching SW 13a is operated to set the calibration mode. Further, the console 19 is operated to set the RGB gain of the imaging sensor 51c of the endoscope 12 to the default.

  Next, according to the flow shown in FIG. 17, a dimming table and a luminance linear table for the normal observation mode are created, and matrix coefficients for the normal observation mode are set. First, in order to create a dimming table for the normal observation mode, a calibration sequence for the normal observation mode is performed. In this calibration sequence, the B-LED 20, the G-LED 21, the R-LED 22, the first special light LED 23, and the second special light LED 24 are turned on, and the light source control signal VB [m] to be applied to each of the LEDs 20 to 24, Blue light, green light, red light, first special light, and second special light are emitted by gradually changing the number of bits of VG [m], VR [m], VSA [m], and VSB [m]. Change intensity and time. Each time the number of bits is changed, the imaging sensor 51c performs imaging in the integrating sphere ST, and outputs an RGB image signal from the imaging sensor 51c.

Then, it is determined whether or not the signal ratio between the RGB image signals output from the image sensor 51c matches the set signal ratio r1: g1: b1 for the normal observation mode. If the set signal ratio r1: g1: b1 is met, the light source control signals VB1 ^* , VG1 ^* , VR1 ^* , VSA1 ^* , VSB1 ^* applied to the LEDs 20 to 24 at that time are set as specific light source control signals. On the other hand, if the set signal ratio r1: g1: b1 does not coincide, the light source control signal applied to the LEDs 20 to 24 at that time is not used as the specific light source control signal.

Next, a table creation sequence for the normal observation mode is performed. First, the specific light source control signals VB1 ^* , VG1 ^* , VR1 ^* , VSA1 ^* , and VSB1 ^* are compared with each other to identify the largest one. Here, assuming that the specific light source control signal VB1 ^* is the largest, the light source control signal VB [m] of the B-LED 20 is set as the reference light source control signal. Next, the control signal ratio calculation unit 46b obtains control signal ratios VG1 ^* / VB1 ^* , VR1 ^* / VB1 ^* between the specific light source control signal VB1 ^* and the specific light source control signals VG1 ^* , VR1 ^* .

Then, the light source control signal VB1 [n] for the brightness step n of the B-LED 20 is set based on the light source control signal VB [m] of the B-LED 20 that is the reference light source control signal. Based on the light source control signal VB1 [m] for the brightness step n and the control signal ratios VG1 ^* / VB1 ^* , VR1 ^* / VB1 ^* , the light source control signal VR1 [n] for the brightness step n of the R-LED 22 and G The light source control signal VG1 [n] for the brightness step n of the LED 21 is obtained. Further, based on the light source control signal VB1 [m] for the brightness step n and the ratios W1 and W2, the light source control signal VSA1 [n] for the brightness step n of the first special light LED 23 and the second special light LED 24. The light source control signal VSB1 [n] for brightness step n is obtained.

  Next, the B1 dimming table is created by associating the light source control signal VB [m] for the brightness step n with the brightness instruction signal n corresponding to the brightness step n. The G1 dimming table, R1 dimming table, SA1 dimming table, and SB1 dimming table are created in the same procedure as the B1 table. These five dimming tables are combined with the B control signal correction table 39, the G control signal correction table 40, the R control signal correction table 41, the SA control signal correction table 42, and the SB control signal correction table 43, respectively. The combined tables TB1, TG1, TR1, TSA1, and TSB1 are stored in the memory 31 in the light source controller.

  Next, a luminance linear table for the normal observation mode is created. First, the brightness instruction signal n is increased bit by bit from “1” as the minimum bit to “N” as the maximum bit, and each time the number of bits of the brightness instruction signal n is increased, the combination table TB1, TG1, With reference to TR1, TSA1, and TSB1, the LEDs 20 to 24 are driven by the light source control signal corresponding to the brightness instruction signal n. Thereby, the first light quantity linear light whose light quantity changes linearly is emitted in a state where the white balance is maintained. Each time the light quantity is changed by increasing the number of bits of the brightness instruction signal n, the imaging sensor 51c performs imaging in the integrating sphere ST, and the brightness instruction signal n is converted into a luminance linear table creation unit in the processor device. To 61.

  Then, based on the RGB image signal obtained when the first light quantity linear light is emitted and the brightness instruction signal n transmitted from the light quantity linear light control unit 47 when the light quantity linear light is emitted, the brightness instruction signal is obtained. A luminance linear RGB image signal in which the signal value of the RGB image signal changes linearly with respect to n is obtained. Then, the RGB image signal and the luminance linear RGB image signal are associated with each other to create the normal observation mode luminance linear table LNT1. The created luminance linear table LNT1 is stored in the luminance linear conversion unit 62a of the normal image processing unit 62.

  Next, matrix coefficients k11 to k33 used in the color correction processing unit 62b are set. First, the LEDs 20 to 24 are controlled to emit blue light, green light, red light, first special light, and second special light at a predetermined light amount ratio, thereby generating color chart equivalent color light. The color subject equivalent color light is irradiated to the white subject portion WST in the integrating sphere ST, and the white subject portion WST is imaged by the imaging sensor 51c. Then, the matrix coefficients k11 to k33 are set so that the image signal (RGB image signal) output from the imaging sensor 51c becomes the target image signal (RGB image signal). This completes the preparation of the dimming table for the normal observation mode, the creation of the luminance linear table, and the setting of the matrix coefficients for the normal observation mode.

  Next, in the same procedure as described above, a dimming table and a luminance linear table for the first special light observation mode are created, and a matrix coefficient for the first special light observation mode is set. The G2 dimming table, the SA2 dimming table, and the SB2 dimming table for the first special light are combined with the G control signal correction table, the SA control signal correction table, and the SB control signal correction table, respectively. These are stored as TSA2 and TSB2 in the memory 31 in the light source controller. The luminance linear table LNT2 for the first special light observation mode is stored in the luminance linear conversion unit of the first special light image processing unit 63.

  Next, in the same procedure as described above, a dimming table and a luminance linear table for the second special light observation mode are created, and a matrix coefficient for the second special light observation mode is set. The G3 dimming table, the R3 dimming table, the SA3 dimming table, and the SB3 dimming table for the second special light are respectively a G control signal correction table, an R control signal correction table, an SA control signal correction table, and an SB control. A combined table TG3, TR3, TSA3, and TSB3 is stored in the memory 31 in the light source control unit in combination with the signal correction table. The luminance linear table LNT3 for the second special light observation mode is stored in the luminance linear conversion unit of the second special light image processing unit 64.

  Next, in the same procedure as described above, a dimming table and a luminance linear table for the third special light observation mode are created, and a matrix coefficient for the third special light observation mode is set. The SB4 dimming table and the SC4 dimming table for the third special light are stored in the memory 31 in the light source control unit as combined tables TSB4 and TSC4 in combination with the SB control signal correction table and the SC control signal correction table, respectively. The The luminance linear table LNT4 for the third special light observation mode is stored in the luminance linear conversion unit of the third special light image processing unit 65. This completes the calibration mode.

  Next, a flow for performing observation using the dimming table obtained by the calibration method of the present invention will be described with reference to the flowchart shown in FIG. First, the light source device 14 and the processor device 16 are turned on. Then, the distal end portion 12d of the calibrated endoscope 12 is inserted into the observation target. Then, the mode switching SW 13a is operated to set a desired observation mode. When the observation of the observation target is completed, the endoscope 12 is removed from the observation target, and the light source device 14 and the processor device 16 are turned off.

  When the normal observation mode is set, the combination tables TB1, TG1, TR1, TSA1, and TSB1 are read from the memory 31 of the light source device. These combination tables TB1, TG1, TR1, TSA1, and TSB1 are stored in the B-LUT 32, the G-LUT 33, the R-LUT 34, the first special light LUT 35, and the second special light LUT 36.

  The light source control unit 27 controls the light emission of the B-LED 20, the G-LED 21, the R-LED 22, the first special light LED 23, and the second special light LED 24 based on the LUTs 32 to 36. Thereby, blue light B, green light G, red light R, first special light SA, and second special light SB are emitted. By controlling the light emission based on the LUTs 32 to 36 in this way, white balance can be maintained regardless of what brightness instruction signal n is input to the light source control unit 27 (that is, the brightness instruction signal). n does not cause a color change).

  Further, the luminance linear conversion unit 62a in the normal image processing unit 62 of the processor device 16 converts the RGB image signal into the luminance linear RGB image signal based on the normal observation mode luminance linear table LNT1. In the luminance linear RGB image signal, the signal value of each image signal changes linearly with respect to the brightness instruction signal n. Further, the color correction processing unit 62b of the processor device 16 generates an RGB image signal for enabling display of the color of the endoscopic image with the target color by matrix calculation based on the matrix coefficients k11 to k33 for the normal observation mode. To do. Then, a normal image is displayed on the monitor 18 based on the RGB image signal that has undergone matrix calculation or the like.

  When the first special light observation mode is set, the combined tables TG2, TSA2, and TSB2 are read from the memory 31 of the light source device 14. These combination tables TG2, TSA2, and TSB2 are stored in the G-LUT 33, the first special light LUT 35, and the second special light LUT 36.

  The light source control unit 27 controls the light emission of the G-LED 21, the first special light LED 23, and the second special light LED 24 based on the LUTs 33, 35, and 36. As a result, green light G, first special light SA, and second special light SB are emitted. By controlling the light emission based on the LUTs 33, 35, and 36 as described above, the color balance can be maintained regardless of the brightness instruction signal n input to the light source control unit 27 (that is, the brightness). The color change does not occur due to the change of the instruction signal n).

  Further, the luminance linear conversion unit in the first special light image processing unit of the processor device 16 converts the RGB image signal into the luminance linear RGB image signal based on the first special light observation mode luminance linear table LNT2. In the luminance linear RGB image signal, the signal value of each image signal changes linearly with respect to the brightness instruction signal n. Further, the color correction processing unit of the processor device 16 generates an RGB image signal for enabling display of the color of the endoscopic image with the target color by matrix calculation based on the matrix coefficient for the first special light observation mode. . Then, the first special light image is displayed on the monitor 18 based on the RGB image signal subjected to the matrix calculation or the like.

  When the second special light observation mode is set, the combined tables TG3, TR3, TSA3, and TSB3 are read from the memory 31 of the light source device 14. These combination tables TG3, TR3, TSA3, and TSB3 are stored in the G-LUT 33, the R-LUT 34, the first special light LUT 35, and the second special light LUT 36.

  The light source control unit 27 controls the light emission of the G-LED 21, the R-LED 22, the first special light LED 23, and the second special light LED 24 based on the LUTs 33 to 36. As a result, green light G, red light R, first special light SA, and second special light SB are emitted. By controlling the light emission based on the LUTs 33 to 36 in this way, the color balance can be maintained regardless of what brightness instruction signal n is input to the light source control unit 27 (that is, the brightness instruction signal). n does not cause a color change).

  Further, the luminance linear conversion unit in the second special light image processing unit of the processor device 16 converts the RGB image signal into the luminance linear RGB image signal based on the second special light observation mode luminance linear table LNT3. In the luminance linear RGB image signal, the signal value of each image signal changes linearly with respect to the brightness instruction signal n. Further, the color correction processing unit of the processor device 16 generates an RGB image signal for enabling display of the color of the endoscopic image with the target color by matrix calculation based on the matrix coefficient for the second special light observation mode. . Then, the second special light image is displayed on the monitor 18 based on the RGB image signal subjected to the matrix calculation or the like.

  When the third special light observation mode is set, the combined tables TSB4 and TSC4 are read from the memory 31 of the light source device 14. The combined tables TSB4 and TSC4 are stored in the second special light LUT 36 and the third special light LUT 37.

  Then, the light source control unit 27 controls the light emission of the second special light LED 24 and the third special light LED 25 based on the LUTs 36 and 37. As a result, the second special light SB and the third special light SC are emitted. By controlling the light emission based on the LUTs 36 and 37 in this way, the color balance can be maintained regardless of what brightness instruction signal n is input to the light source control unit 27 (that is, the brightness instruction signal). n does not cause a color change).

  In addition, the luminance linear conversion unit in the third special light image processing unit of the processor device 16 converts the RGB image signal into a luminance linear RGB image signal based on the third special light observation mode luminance linear table LNT4. In the luminance linear RGB image signal, the signal value of each image signal changes linearly with respect to the brightness instruction signal n. Further, the color correction processing unit of the processor device 16 generates an RGB image signal for enabling display of the color of the endoscopic image with the target color by matrix calculation based on the matrix coefficient for the third special light observation mode. . Then, the third special light image is displayed on the monitor 18 based on the RGB image signal subjected to the matrix calculation or the like.

  In the above-described embodiment, the combined table, luminance linear table, and matrix coefficient for each observation mode obtained in the calibration mode are used as the scope ID of the endoscopes 12 and 100 (denoted as “ID” in FIG. 1). It is preferable to store them in the memory 31 in the light source device 14 in association with each other. When the calibrated endoscopes 12 and 100 are attached to the light source device 14 and the processor device 16, the scope ID of the endoscopes 12 and 100 is an ID reading unit (indicated as “RD” in FIG. 1). It is preferable that the combined table, luminance linear table, and matrix coefficient for each observation mode corresponding to the read scope ID are read from the memory 31 and used.

  In the above embodiment, the calibration of the present invention is performed for an endoscope having a color imaging sensor. In addition to this, the present invention is applied to a monochrome plane sequential endoscope. Calibration may be performed.

Note that the above embodiment includes the following technical idea regarding luminance linear conversion.
[Additional Item 1]
A plurality of semiconductor light sources that emit a plurality of illumination lights in different wavelength ranges, a light source control unit that controls each semiconductor light source with a light source control signal, and the brightness of each illumination light in N stages (N is an integer of 2 or more) An endoscope having a brightness instruction signal generation unit for generating a brightness instruction signal n for instructing the light source control unit to perform control to be changed at step n (n is an integer from 1 to N). In a calibration method for a mirror system,
A light amount linear light emitting step for controlling the plurality of semiconductor light sources to emit light amount linear light in which light amounts of the plurality of illumination lights change linearly with respect to the brightness instruction signal n;
An image signal acquisition step of capturing a reference subject illuminated with the light amount linear light with an image sensor and acquiring an image signal at the time of light amount linear light emission;
A luminance linear signal generation step for generating a luminance linear image signal whose signal value changes linearly with respect to the brightness instruction signal n based on the brightness instruction signal n and the light amount linear light emission image signal;
A calibration method, comprising: an association step of creating an intensity linear table by associating the light quantity linear light emission image signal and the intensity linear image signal.

[Additional Item 2]
The calibration method according to claim 1, wherein the plurality of semiconductor light sources include an R-LED that emits red light, a G-LED that emits green light, and a B-LED that emits blue light.

[Additional Item 3]
The plurality of semiconductor light sources include a first special light LED that emits a first special light having a first wavelength band at least partially different from the red light, the green light, and the blue light, and the red light, the green light, and the blue light. And a plurality of special light LEDs including at least a second special light LED that emits a second special light having a second wavelength band that is at least partially different from the first special light. 2. The calibration method according to 2.

[Additional Item 4]
The endoscope system includes a normal observation mode in which at least the R-LED, G-LED, and B-LED are lit to emit white light, and at least the first and second special light LEDs are lit. Has a special observation mode that emits light,
4. The calibration method according to item 3, wherein the luminance linear table is created for each observation mode.

[Additional Item 5]
Using the luminance linear table obtained by the calibration method according to any one of appendices 1 to 4, converting an image signal obtained by imaging an observation target with the imaging sensor into the luminance linear image signal. Endoscope system characterized by.

[Additional Item 6]
A storage unit that associates and stores the luminance linear table and the scope ID of the endoscope;
The endoscope system according to claim 5, further comprising an ID reading unit that reads a scope ID of the endoscope.

[Additional Item 7]
A plurality of semiconductor light sources that emit a plurality of illumination lights in different wavelength ranges, a light source control unit that controls each semiconductor light source with a light source control signal, and the brightness of each illumination light in N stages (N is an integer of 2 or more) An endoscope having a brightness instruction signal generation unit for generating a brightness instruction signal n for instructing the light source control unit to perform control to be changed at step n (n is an integer from 1 to N). In the mirror system,
A light amount linear light control unit for controlling the plurality of semiconductor light sources in order to emit light amount linear light in which light amounts of the plurality of illumination lights change linearly with respect to the brightness instruction signal n;
An image signal acquisition unit that captures an image signal of a reference subject illuminated with the light amount linear light with an imaging sensor and acquires an image signal at the time of light amount linear light emission; and
A luminance linear signal generation unit that generates a luminance linear image signal whose signal value linearly changes with respect to the luminance instruction signal n based on the luminance instruction signal n and the light amount linear light emission image signal;
An endoscope system comprising: an association unit that creates an intensity linear table by associating the light amount linear light emission image signal and the intensity linear image signal.

10 Endoscope system 12,100 Endoscope 20 B-LED
21 G-LED
22 R-LED
23 First special light LED
24 Second special light LED
25 Third special light LED
48 Color chart equivalent color light control unit 62 Color correction processing unit 67 Matrix operation unit 68 Matrix coefficient setting unit (condition setting unit)
WST White subject (white reference subject)

Claims (10)

In an endoscope system calibration method including a color correction processing unit that performs color correction processing for converting a first color image signal into a second color image signal for enabling display of a target color.
Illumination light that generates a color chart equivalent color light that is a color chart color by combining a plurality of illumination lights by emitting a plurality of illumination lights having different wavelength bands from a plurality of semiconductor light sources at a specific light quantity ratio. Generation step;
An illumination step of illuminating a white reference subject with the color chart equivalent color light generated in the illumination light generation step;
An image signal acquisition step of capturing an image signal for first calibration by capturing an image of the white reference subject being illuminated with the color chart equivalent color light in the illumination step;
A condition setting step of setting conditions for the color correction processing based on the first calibration image signal acquired in the image signal acquisition step;
In the light quantity ratio-image signal table showing a relationship between a light quantity ratio between the plurality of illumination lights and an image signal obtained when the white reference subject is imaged with a plurality of illumination lights having the light quantity ratio, For color chart equivalent color light that sets a light quantity ratio corresponding to a second calibration image signal obtained when the color chart is imaged by the imaging sensor as the specific light quantity ratio necessary for light emission of the color chart equivalent color light A calibration method further comprising a light amount ratio setting step. The color correction process is a matrix operation for converting the first color image signal into the second color image signal;
2. The calibration method according to claim 1, wherein in the condition setting step, a matrix coefficient used for the matrix calculation is set based on the first calibration image signal acquired in the image signal acquisition step. In the condition setting step,
3. The calibration method according to claim 2, wherein the matrix coefficient is set so that the first calibration image signal acquired in the image signal acquisition step approaches a target image signal. Wherein the plurality of semiconductor light sources, the calibration of claims 1 to 3 any one of claims, characterized in that it has R-LED which emits red light, G-LED emitting green light, the B-LED that emits blue light Method. The plurality of semiconductor light sources include a first special light LED that emits a first special light having a first wavelength band at least partially different from the red light, the green light, and the blue light, and the red light, the green light, and the blue light. And a plurality of special light LEDs including at least a second special light LED that emits a second special light having a second wavelength band that is at least partially different from the first special light. 4. The calibration method according to 4 . The endoscope system includes a normal observation mode in which at least the R-LED, G-LED, and B-LED are lit to emit white light, and at least the first and second special light LEDs are lit. Has a special observation mode that emits light,
6. The calibration method according to claim 5 , wherein conditions for the color correction processing are set for each observation mode.   The endoscope system according to claim 2, wherein the matrix calculation is performed based on a matrix coefficient set by the calibration method according to claim 2. A storage unit for storing the matrix coefficient and the scope ID of the endoscope in association with each other;
The endoscope system according to claim 7 , further comprising an ID reading unit that reads a scope ID of the endoscope. In an endoscope system including a color correction processing unit that performs a color correction process for converting a first color image signal into a second color image signal for enabling display of a target color.
A plurality of semiconductor light sources emitting a plurality of illumination lights having different wavelength bands from each other;
A color that generates a color chart equivalent color light that is a color chart color by combining the plurality of illumination lights by controlling the plurality of semiconductor light sources so that the plurality of illumination lights are emitted at a specific light quantity ratio. A chart equivalent color light control unit;
An image signal acquisition unit that acquires an image signal for first calibration by imaging a white reference subject illuminated with the color chart equivalent color light by an imaging sensor;
A condition setting unit that sets conditions for the color correction processing based on the first calibration image signal acquired by the image signal acquisition unit;
There is a light quantity ratio-image signal table indicating a relationship between a light quantity ratio between the plurality of illumination lights and an image signal obtained when the white reference subject is imaged with a plurality of illumination lights having the light quantity ratio. And
In the table between the light quantity ratio and the image signal, the light quantity ratio corresponding to the second calibration image signal obtained when the color chart is imaged by the imaging sensor is specified as necessary for light emission of the color chart equivalent color light. An endoscope system characterized by being set as a light quantity ratio. The color correction process is a matrix operation for converting the first color image signal into the second color image signal;
The condition setting unit, based on the first image signal for calibration obtained by the image signal acquisition unit, according to claim 9, characterized in that it comprises a matrix coefficient setting unit for setting matrix coefficients used in the matrix operation Endoscope system.

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