Endoscope system and operation method thereof

Abstract

To provide an endoscope system capable of acquiring still images in a plurality of lighting modes without requiring a troublesome operation by a user, and an operation method thereof.SOLUTION: When a still image acquisition operation OP is performed, a light source control part 22 switches a lighting mode at least once in a still image acquisition period TP of acquiring a still image, and acquires a still image to be observed for each lighting mode. After the still image acquisition period TP, the light source control part 22 switches to a normal mode being a lighting mode before the still image acquisition operation OP.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an endoscope system for acquiring still images in multiple illumination modes and a method of operating the same. [Background technology]

[0002] In an endoscope system, an observation target is irradiated with illumination light from an endoscope, and an image of the observation target is captured by an imaging sensor of the endoscope to obtain an RGB image signal, which is then displayed on a display. In addition to the normal observation mode, a special light mode with a different wavelength band is also used to emphasize superficial blood vessels and deep blood vessels, and the resulting image is displayed on a display (for example, Patent Documents 1 and 2).

[0003] If a region of particular interest appears during the observation, the doctor switches the illumination mode to normal light or special light and continues the observation. If necessary, the doctor can also record still images in the current illumination mode by operating the freeze button (still image capture switch) on the endoscope. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3586157 [Patent Document 2] Patent No. 2686089 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Documents 1 and 2, when capturing still images of the same area of ​​interest in multiple illumination modes, it is necessary to sequentially record the still images while sequentially switching between illumination modes, which results in the time-consuming task of changing illumination modes and operating the freeze button multiple times to capture still images.

[0006] An object of the present invention is to provide an endoscope system and an operation method thereof that can acquire still images in a plurality of illumination modes without requiring the user to perform operations. [Means for solving the problem]

[0007] The endoscopic system of the present invention comprises a light source unit that emits illumination light, a first processor that controls the illumination light according to an illumination mode, an endoscope having an imaging sensor, and a second processor that processes images obtained by imaging an object to be observed with the imaging sensor, and there are multiple illumination modes, each of which has a different wavelength component of the illumination light.When a still image acquisition operation is performed, the first processor switches the illumination mode at least once during the still image acquisition period in which a still image is acquired, and acquires a still image of the object to be observed for each illumination mode.After the still image acquisition period, the first processor switches to the illumination mode that was used before the still image acquisition operation.

[0008] Preferably, before a still image acquisition operation is performed, the first processor controls the illumination light to be continuously emitted. Preferably, the illumination pattern of the illumination mode that is performed when a still image acquisition operation is performed can be changed by setting.

[0009] Preferably, the second processor switches the imaging parameters of the imaging sensor from the first imaging parameters to second imaging parameters different from the first imaging parameters during the still image acquisition period, and returns the imaging parameters to the first imaging parameters after the still image acquisition period.

[0010] It is preferable that the first processor switches the light source parameters of the illumination light from the first light source parameters to second light source parameters different from the first light source parameters during the still image acquisition period, and returns the light source parameters to the first light source parameters after the still image acquisition period.

[0011] The light source parameter is preferably at least one of a duty ratio of the illumination light and a light emission cycle of the illumination light. Preferably, the second processor acquires a plurality of still images each time the illumination mode is switched during the still image acquisition period, and stores the still image with the least blur among the plurality of still images in the storage memory as the still image to be saved.

[0012] The second processor preferably stores the plurality of still images acquired for each lighting mode during the still image acquisition period in a temporary storage memory, and deletes the still images in the temporary storage memory when saving the still images to be saved. The light source unit preferably has a plurality of semiconductor light sources that emit illumination light having different wavelength components.

[0013] The present invention provides an operating method for an endoscopic system having a light source unit that emits illumination light, a first processor that controls the illumination light in accordance with an illumination mode, an endoscope having an imaging sensor, and a second processor that processes images obtained by imaging an object to be observed with the imaging sensor, wherein there are multiple illumination modes and the wavelength components of the illumination light differ for each illumination mode, wherein when a still image acquisition operation is performed, the first processor switches the illumination mode at least once during a still image acquisition period in which a still image is acquired, and acquires a still image of the object to be observed for each illumination mode, and after the still image acquisition period, the first processor switches to the illumination mode that was used before the still image acquisition operation. [Effects of the Invention]

[0014] According to the present invention, still images can be acquired in a plurality of lighting modes without requiring the user to perform any complicated operations. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of an endoscope system. [Figure 2] FIG. 2 is a block diagram showing the functions of the endoscope system. [Figure 3] FIG. 1 is an explanatory diagram showing broadband light. [Figure 4] FIG. 4 is an explanatory diagram showing a first illumination light. [Figure 5] FIG. 10 is an explanatory diagram showing a second illumination light. [Figure 6] 10A and 10B are explanatory diagrams showing the illumination light emission control when a still image acquisition operation is performed. [Figure 7] FIG. 10 is an image diagram showing a light emission pattern setting screen. [Figure 8] 10A and 10B are explanatory diagrams showing imaging control when a still image acquisition operation is performed. [Figure 9] 10A and 10B are explanatory diagrams showing imaging control and light emission control when the imaging sensor is a global shutter type. [Figure 10] 10A and 10B are explanatory diagrams showing imaging control and light emission control when the imaging sensor is of a rolling shutter type. [Figure 11] FIG. 10 is an explanatory diagram showing storage control of a storage still image. [Figure 12] 10A and 10B are explanatory diagrams showing another embodiment of illumination light emission control when a still image acquisition operation is performed. [Figure 13] 1 is a flowchart showing a series of steps of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1, an endoscopic system 10 of the present invention includes an endoscope 11, a light source device 12, a processor device 13, a display 14, and a user interface (UI) 15. The endoscope 11 is optically connected to the light source device 12 and electrically connected to the processor device 13. The light source device 12 supplies illumination light to the endoscope 11. Although the light source device 12 and the processor device 13 are separate entities, they may be integrated into one device.

[0017] The endoscope 11 illuminates the subject with illumination light, captures an image of the subject, and acquires an endoscopic image. The endoscope 11 has an insertion section 11a that is inserted into a living body (inside a subject) that has the subject, and an operation section 11b that is provided at the base end of the insertion section 11a. A bending section 11c and a tip section 11d are provided at the tip side of the insertion section 11a. The bending section 11c is bent in a desired direction by operating the operation section 11b. The tip section 11d irradiates the subject with illumination light and receives reflected light from the subject to capture an image of the subject. The operation section 11b has a mode change switch 11e that is used for mode change operation, a zoom operation section 11f that is used for zoom operation, and a still image acquisition switch 11g.

[0018] The processor device 13 is electrically connected to the display 14 and the user interface 15. The processor device 13 receives image signals from the endoscope 11 and performs various processes based on the image signals. An external recording unit (not shown) for recording images, image information, etc. may be connected to the processor device 13. The display 14 outputs and displays images of a subject and image information, etc., which have been image-processed by the processor device 13. The user interface 15 has a keyboard, mouse, touchpad, microphone, foot pedal, etc., and has the function of accepting input operations such as function settings.

[0019] As shown in FIG. 2, in the endoscope system 10, the light source device 12 transmits emitted illumination light to the endoscope 11 via a light guide LG (Light Guide), and the endoscope 11 transmits an image signal captured using the illumination light to the processor device 13, and the processor device 13 generates an image to be displayed on the display 14 and performs image analysis.

[0020] The light source device 12 includes a light source unit 20 that emits one or more illumination lights and a light source control unit 22 that controls the illumination lights according to an illumination mode. The light source unit 20 preferably includes multiple semiconductor light sources that emit illumination lights having different wavelength components. For example, the light source unit 20 includes a purple semiconductor light source that emits purple light, a blue semiconductor light source that emits blue light, a green semiconductor light source that emits green light, and a red semiconductor light source that emits red light. The semiconductor light sources are preferably laser diodes (LDs) or light emitting diodes (LEDs). The light emitted by the light source unit 20 is incident on a light guide LG. The light source control unit 22 is configured by a first processor. Details of the illumination mode and the control of the illumination light will be described later. The light guide LG is built into the endoscope 11 and the universal cord. The universal cord is a cord that connects the endoscope 11 to the light source device 12 and the processor device 13. The light guide 29 propagates light from the light source unit 20 to the tip portion 11 d of the endoscope 11 .

[0021] The endoscope 11 is provided with an illumination optical system 30 and an imaging optical system 40. The illumination optical system 30 has an illumination lens 32, and illumination light propagated by the light guide LG is irradiated onto a subject via the illumination lens 32. The imaging optical system 40 has an objective lens 42, a zoom lens 43, and an imaging sensor 44. Reflected light of the illumination light returning from the subject irradiated with the illumination light is incident on the imaging sensor 44 via the objective lens 42 and the zoom lens 43. As a result, an image of the subject is formed on the imaging sensor 44, which is a color imaging sensor.

[0022] The imaging sensor 44 has B pixels with blue color filters, G pixels with green color filters, and R pixels with red color filters. An imaging control unit 45 controls the imaging sensor 44. The imaging control unit 45 is composed of a second processor together with a central control unit 49 of the processor device 13. The image formed on the imaging sensor 44 is transmitted as an image signal to the processor device 13 via a CDS / AGC (Correlated Double Sampling / Automatic Gain Control) circuit 46 and an A / D (Analog / Digital) converter 48.

[0023] In the processor device 13, programs for each process are incorporated in a program memory (not shown). A central control unit 49 formed by the second processor executes the programs in the program memory to realize the functions of an image signal acquisition unit 50, a DSP (Digital Signal Processor) 51, a noise reduction unit 52, an image processing unit 53, an output control unit 54, a still image acquisition unit 55, and a still image storage control unit 56. Information such as an image output from the output control unit 54 is displayed on the display 14. The processor device 13 is also provided with a storage memory 58 and a temporary storage memory 59.

[0024] The image processing unit 53 and the output control unit 54 acquire and store still images, and also control image display based on illumination mode control in conjunction with the light source control unit 22. These will be described in detail later. Note that images based on image display control based on illumination mode control include a normal image as an image in normal mode, a superficial vessel enhancement image as an image in superficial vessel enhancement mode, and a deep vessel enhancement image as an image in deep vessel enhancement mode.

[0025] The illumination modes and illumination light control are described below. There are multiple illumination modes, each with a different illumination light emission pattern. The illumination modes include at least a normal mode that emits broadband light such as white light, a superficial vessel enhancement mode that emits first illumination light containing many short-wavelength components such as purple and blue to emphasize superficial blood vessels, and a deep vessel enhancement mode that emits second illumination light containing many medium-wavelength components such as green to emphasize deep blood vessels.

[0026] In the normal mode, as shown in Fig. 3, when blue light B, green light G, and red light R are emitted as illumination light, the blue light B, green light G, and red light R are emitted as broadband light with approximately the same light intensity. In the superficial vessel enhancement mode, as shown in Fig. 4, when purple light V, blue light B, green light G, and red light R are emitted, the light intensities of the purple light V and blue light B as the first illumination light are made higher than those of the green light G and red light R. In the deep vessel enhancement mode, as shown in Fig. 5, when blue light B, green light G, and red light R are emitted, the light intensities of the green light G and red light R as the second illumination light are made higher than those of the blue light B.

[0027] Light source control and image control during the still image acquisition operation will be described below. The still image acquisition operation is performed by operating the still image acquisition switch 11g. When the still image acquisition operation is performed, the light source control unit 22 switches the illumination mode at least once during the still image acquisition period in which the still image is acquired, and the still image acquisition unit 55 acquires a still image of the observation target for each illumination mode. After the still image acquisition period, the light source control unit 22 switches to the illumination mode before the still image acquisition operation. The still image acquisition period starts with the still image acquisition operation and ends when all of the preset illumination mode switching patterns have been executed. Furthermore, the illumination mode before the still image acquisition operation is set to the normal mode, and only broadband light is continuously emitted. However, this is not limited to this, and other illumination light, such as the first illumination light or the second illumination light, may be continuously emitted.

[0028] Specifically, as shown in Fig. 6, if the light source control unit 22 controls the illumination mode in the normal mode before performing the still image acquisition operation OP, then by performing the still image acquisition operation OP, the light source control unit 22 switches from the normal mode CM to the superficial blood vessel enhancement mode to control the emission of illumination light during the still image acquisition period TP, and also switches from the superficial blood vessel enhancement mode to the deep blood vessel enhancement mode to control the emission of illumination light. Accordingly, the still image acquisition unit 55 acquires a still image in the normal mode, a still image in the superficial blood vessel enhancement mode, and a still image in the deep blood vessel enhancement mode. These acquired still images are stored in the storage memory 58.

[0029] It is preferable that the illumination pattern of the illumination mode executed when a still image acquisition operation is performed can be changed by setting. Specifically, when the user interface 15 is operated to set the setting change mode, an illumination pattern setting screen 60 is displayed on the display 14 as shown in FIG. 7. The illumination pattern setting screen 60 displays the illumination pattern of the illumination mode executed when a still image acquisition operation is performed. Specifically, the illumination pattern setting screen 60 displays that the illumination patterns of the illumination modes are normal mode, superficial blood vessel emphasis mode, and deep blood vessel emphasis mode in this order. On the illumination pattern setting screen 60, the order of the modes can be changed by changing the settings (for example, changing the order to superficial blood vessel emphasis mode, deep blood vessel emphasis mode, and normal mode). Furthermore, the number of modes can be increased or decreased by changing the settings. For example, the deep blood vessel emphasis mode can be eliminated and changed to normal mode and superficial blood vessel emphasis mode.

[0030] Preferably, the imaging control unit 45 switches the imaging parameters of the imaging sensor 44 from the first imaging parameters to second imaging parameters different from the first imaging parameters during the still image acquisition period TP, and returns the imaging parameters to the first imaging parameters after the still image acquisition period TP. Specifically, the imaging parameters include a frame rate (fps (flames per second)). In this case, if the first imaging parameter is 60 fps (flames per second) and the second imaging parameter is 90 fps, as shown in FIG. 8, before the still image acquisition period TP, images in the normal mode are captured at 60 fps. After the still image acquisition period TP begins, images in the normal mode, superficial blood vessel enhancement mode, and deep blood vessel enhancement mode are each captured at 90 fps. Then, after the still image acquisition period TP, images in the normal mode are captured at 60 fps. Other imaging parameters include analog gain and digital gain applied to images. The imaging parameters may be switched by the central control unit 49 instead of the imaging control unit 45.

[0031] If the imaging sensor 44 is of the global shutter type, signals are read out from the imaging sensor 44 instantaneously, as shown in Fig. 9, and therefore, during still image acquisition during the still image acquisition period TP, the broadband light in the normal mode, the first illumination light in the superficial blood vessel enhancement mode, and the second illumination light in the deep blood vessel enhancement mode can be switched instantaneously without a shading period after the exposure period TE. On the other hand, if the imaging sensor 44 is of the rolling shutter type, signals are read out sequentially from the imaging sensor 44, as shown in Fig. 10, and therefore, during still image acquisition during the still image acquisition period TP, the illumination light in the normal mode, the first illumination light in the superficial blood vessel enhancement mode, and the second illumination light in the deep blood vessel enhancement mode are switched after a certain shading period TS has elapsed after the exposure period TE.

[0032] Preferably, the light source control unit 22 switches the light source parameter of the illumination light during the still image acquisition period TP from a first light source parameter to a second light source parameter different from the first light source parameter, and returns the light source parameter to the first light source parameter after the still image acquisition period TP. Specifically, the light source parameter may be a duty ratio. In this case, if the first duty ratio is set as the first light source parameter and the second duty ratio, which is shorter than the first duty ratio, is set as the second light source parameter, as shown in FIGS. 9 and 10 , before the still image acquisition period TP, broadband light in normal mode is emitted at a first duty ratio DT1. After the still image acquisition period TP begins, broadband light in normal mode, first illumination light in superficial blood vessel enhancement mode, and second illumination light in deep blood vessel enhancement mode are emitted at a second duty ratio DT2, respectively. Then, after the still image acquisition period TP ends, broadband light in normal mode is emitted at the first duty ratio DT1.

[0033] Another light source parameter is the light emission cycle of the illumination light. As described above, since the frame rate is switched outside or within the still image acquisition period TP, the light source control unit 22 also switches the light emission cycle of the illumination light to match the switched frame rate. By using this light emission cycle as a unit, the light intensity of the illumination light is increased or decreased, thereby performing dimming control so that the image has appropriate brightness.

[0034] When the light source parameter is the light emission period, if the first light source parameter is the first light emission period and the second light source parameter is a second light emission period longer than the first light emission period, as shown in FIG. 10 , before the still image acquisition period TP, broadband light in normal mode is emitted at a first light emission period LP1. After the still image acquisition period TP, broadband light in normal mode, first illumination light in superficial blood vessel enhancement mode, and second illumination light in deep blood vessel enhancement mode are emitted at a second light emission period LP2, respectively. Then, after the still image acquisition period TP, broadband light in normal mode is emitted at the first light emission period LP1. Note that the second light emission period is longer than the first light emission period, but it may also be shorter. Furthermore, even if the imaging sensor 44 uses a global shutter system, light emission control may be performed using different first and second light emission periods outside or within the still image acquisition period TP.

[0035] During the still image acquisition period TP, the still image saving control unit 56 acquires a plurality of still images each time the lighting mode is switched, and saves the still image with the least blur among the plurality of still images as a still image to be saved in the saving memory 58. In this case, the still image saving control unit 56 saves the plurality of still images acquired for each lighting mode during the still image acquisition period TP in the temporary saving memory 59, and deletes the still images in the temporary saving memory when saving the still images to be saved.

[0036] 11, when switching between normal mode, superficial blood vessel enhancement mode, and deep blood vessel enhancement mode during still image acquisition period TP, 10 frames of still images are acquired for each of the normal mode, superficial blood vessel enhancement mode, and deep blood vessel enhancement mode. When 10 frames of still images for each mode are stored in temporary storage memory 59, the still images in temporary storage memory 59 are deleted before storage. As a result, all still images acquired before still image acquisition period TP are cleared from temporary storage memory and excluded from selection of still images to be stored based on blur.

[0037] When 10 frames of still images for each mode are saved in temporary storage memory 59 during still image acquisition period TP, the still image with the least blur among the 10 frames of still images for normal mode saved in temporary storage memory 59 is saved as the still image for normal mode to be saved in storage memory 58. Similarly, based on the blur, still images for saving in superficial blood vessel enhancement mode and still images for saving in deep blood vessel enhancement mode are saved in storage memory 58. Note that as for the method of reflecting blur, there is a method of determining blur when the edge components of an image are below a certain value, as well as a method of determining blur when the high frequency components of an image are below a certain value.

[0038] In the above embodiment, the mode before the still image acquisition operation is also executed during the still image acquisition period, as in the normal mode, but the mode before the still image acquisition operation does not have to be executed during the still image acquisition period. For example, as shown in Figure 12, if the mode before the still image acquisition operation is the normal mode, the normal mode is not executed during the still image acquisition period TP, and only the layer blood vessel enhancement mode and the deep blood vessel enhancement mode are executed.

[0039] Next, a series of steps in the present invention will be described with reference to the flowchart in Figure 13. Before the still image acquisition period TP in which a still image is acquired, broadband light is illuminated on the object of observation in normal mode, and an image in normal mode is displayed on the display 14. The still image acquisition period TP is entered by operating the still image acquisition switch 11g. During the still image acquisition period TP, the light source control unit 22 switches the illumination mode at least once and acquires a still image of the object of observation for each illumination mode. The acquired still images are saved in the storage memory 58. After the still image acquisition period TP, the light source control unit 22 switches back to normal mode.

[0040] In the above embodiment, the hardware structure of processing units that perform various processes, such as the light source control unit 22, the image signal acquisition unit 50, the DSP 51, the noise reduction unit 52, the image processing unit 53, the output control unit 54, the still image acquisition unit 55, and the still image storage control unit 56, is made up of various processors as shown below. The various processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes software (programs) and functions as various processing units, a GPU (Graphical Processing Unit), a programmable logic device (PLD), which is a processor whose circuit configuration can be changed after manufacture, such as an FPGA (Field Programmable Gate Array), and a dedicated electrical circuit, which is a processor having a circuit configuration designed specifically for performing various processes.

[0041] A single processing unit may be configured with one of these various processors, or may be configured with a combination of two or more processors of the same or different types (e.g., multiple FPGAs, a combination of a CPU and an FPGA, or a combination of a CPU and a GPU). Also, multiple processing units may be configured with a single processor. Examples of multiple processing units configured with a single processor include, first, a configuration in which one processor is configured with a combination of one or more CPUs and software, as typified by client or server computers, and this processor functions as multiple processing units. Second, a configuration in which a processor is used to realize the functions of an entire system including multiple processing units on a single IC (Integrated Circuit) chip, as typified by a system-on-chip (SoC). In this way, the various processing units are configured with one or more of the above-mentioned various processors as a hardware structure.

[0042] Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit formed by combining circuit elements such as semiconductor elements, and the hardware structure of the memory unit is a storage device such as an HDD (Hard Disc Drive) or an SSD (Solid State Drive). [Explanation of symbols]

[0043] 10 Endoscopy System 11 Endoscopy 11a Insertion part 11b Operation section 11c Curved section 11d Tip 11e Mode switch 11f Zoom control 11g Still image capture switch 12 Light source device 13 Processor unit 14 Display 15 User Interface 20 Light source section 22 Light source control unit 30 Illumination optical system 32 Lighting lens 40 Imaging optical system 42 Objective Lens 43 Zoom Lens 44 Image sensor 45 Imaging control unit 46 CDS / AGC circuit 48 A / D converters 50 Image signal acquisition unit 51 DSP 52 Noise reduction section 53 Image processing section 54 Output control section 60 Lighting pattern setting screen LG Light Guide B blue light G green light R red light OP Still image acquisition operation TP still image acquisition period TE exposure period TS Dark period DT1 1st duty ratio DT2 Second duty ratio LP1 First light emission cycle LP2 Second light emission cycle

Claims

1. an endoscope including a light source unit that emits illumination light, a first processor that controls the illumination light in accordance with an illumination mode, an endoscope having an image sensor, and a second processor that processes an image obtained by capturing an image of an observation target with the image sensor; There are a plurality of illumination modes, and the wavelength component of the illumination light differs for each illumination mode; when a still image acquisition operation is performed, the first processor switches the illumination mode at least once during a still image acquisition period for acquiring a still image, and acquires a still image of the observation target for each illumination mode; After the still image acquisition period, the first processor switches to the illumination mode before the still image acquisition operation.

2. The endoscope system according to claim 1 , wherein the first processor controls the illumination light to be emitted continuously before the still image acquisition operation is performed.

3. The endoscope system according to claim 1 , wherein the light emission pattern of the illumination mode that is performed when the still image acquisition operation is performed can be changed by settings.

4. 2. The endoscope system according to claim 1, wherein the second processor switches the imaging parameters of the imaging sensor during the still image acquisition period from first imaging parameters to second imaging parameters different from the first imaging parameters, and returns the imaging parameters to the first imaging parameters after the still image acquisition period.

5. 2. The endoscope system according to claim 1, wherein the first processor switches the light source parameters of the illumination light during the still image acquisition period from first light source parameters to second light source parameters different from the first light source parameters, and returns the light source parameters to the first light source parameters after the still image acquisition period.

6. The endoscope system according to claim 5 , wherein the light source parameter is at least one of a duty ratio of the illumination light and a light emission cycle of the illumination light.

7. 2. The endoscope system according to claim 1, wherein the second processor acquires a plurality of still images during the still image acquisition period each time the illumination mode is switched, and stores the still image with the least blur among the plurality of still images in a storage memory as a still image to be saved.

8. the second processor stores the plurality of still images acquired for each lighting mode during the still image acquisition period in a temporary storage memory; 8. The endoscope system according to claim 7, wherein when the still image for storage is stored, the still image in the temporary storage memory is deleted.

9. 9. The endoscope system according to claim 1, wherein the light source unit includes a plurality of semiconductor light sources that emit the illumination light having wavelength components different from each other.

10. An operation method for an endoscope system comprising: a light source unit that emits illumination light; a first processor that controls the illumination light in accordance with an illumination mode; an endoscope having an image sensor; and a second processor that processes an image obtained by capturing an image of an observation target with the image sensor, wherein there are a plurality of illumination modes, and the wavelength components of the illumination light differ for each illumination mode, when a still image acquisition operation is performed, the first processor switches the illumination mode at least once during a still image acquisition period for acquiring a still image, and acquires a still image of the observation target for each illumination mode; A method for operating an endoscope system, wherein after the still image acquisition period, the first processor switches to the illumination mode before the still image acquisition operation.

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