JP4459506B2 - Automatic dimming device for endoscope and electronic endoscope device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an endoscope apparatus in which an endoscope (scope) is inserted into an organ such as a stomach and an image of a predetermined part can be observed, and in particular, observation is performed so that the brightness of a subject image is constant. The present invention relates to automatic light control for adjusting the amount of illumination light applied to a part.
[0002]
[Prior art]
In a conventional endoscope apparatus, the brightness of a subject (subject brightness) is detected based on an image signal corresponding to the subject image, and the amount of illumination light is adjusted in comparison with a reference value indicating the appropriate brightness of the subject. Is done. If the luminance value is larger than the reference value, the diaphragm is closed to reduce the light amount. Conversely, if the luminance value is smaller than the reference value, the diaphragm is opened to increase the light amount. As the value representing the brightness of the subject image to be compared with the reference value, an average luminance value indicating the average brightness of the entire subject or a peak value indicating the maximum luminance is applied, and the operator is provided in the processor. The reference value level can be changed by operating the switch.
[0003]
[Problems to be solved by the invention]
When the light intensity is adjusted by comparing the average luminance value with the reference value, halation (a state in which a part of the subject image is projected to be white due to being too bright) is likely to occur, which hinders inspection, treatment, and the like. On the other hand, when the light intensity is adjusted by comparing the peak luminance value with the reference value, the occurrence of halation can be suppressed, but the observed subject image tends to be dark overall. Although the brightness problem can be solved to some extent by changing the setting of the reference value level, it is difficult for the operator to change the setting of the reference value level during the endoscope operation. For this reason, it is difficult to always maintain the brightness of the subject at an appropriate level during the treatment.
[0004]
Accordingly, an object of the present invention is to obtain an electronic endoscope apparatus and an endoscope automatic light control apparatus that can perform light amount adjustment for maintaining the subject image at an appropriate brightness while suppressing the occurrence of halation.
[0005]
[Means for Solving the Problems]
An electronic endoscope apparatus according to the present invention is an electronic endoscope apparatus including a video scope having an image sensor and a processor to which the video scope is connected. The processor processes an image signal read from the image sensor. A video signal is output to a monitor or the like. The electronic endoscope apparatus according to the present invention, in order to obtain histogram data, histogram processing means for performing histogram processing based on an image signal read from the image sensor, and whether or not halation has occurred based on the histogram data. Halation detecting means for detecting. For example, a halation occurrence ratio indicating the ratio of the number of high-luminance pixels to the total number of pixels constituting the subject image is calculated based on the histogram data, and it is determined whether or not the halation occurrence ratio is a value other than 0. Thus, the halation may be detected. The luminance value indicating the brightness of the subject image is set to any value in the range of 0 to 255 as the luminance level, for example. The high luminance pixel is a pixel having a luminance value equal to or higher than the halation boundary luminance value, and the halation boundary luminance value is a luminance value that is a threshold value (boundary value) that is regarded as occurrence of halation. When the luminance value is in the range of 0 to 255, it is set to a value of approximately 200 to 230. Or you may set to any value of 220-230.
[0006]
In addition, the electronic endoscope apparatus includes a representative luminance value calculation unit that calculates a representative luminance value indicating the representative brightness of the subject image based on the image signal, and whether or not the representative luminance value is equal to or less than the reference luminance value. And representative luminance value determining means. For example, a luminance average value indicating the average brightness of the subject image or a peak luminance value that is the maximum luminance value in the entire subject image may be applied to the representative luminance value. The reference luminance value indicates a representative luminance value that serves as a reference for determining whether or not to adjust the light amount. For example, when the representative luminance value is a luminance average value, the reference luminance value is within a possible range of luminance values. The luminance value near the middle may be used as the reference luminance value. Regarding the light amount adjustment, the electronic endoscope apparatus includes a light amount adjustment unit that adjusts the amount of light that illuminates the subject so that the brightness of the subject image displayed on a monitor or the like is constant, and is provided at predetermined time intervals. Adjust the light intensity. For example, it may be performed in accordance with the readout period of the image signal for one frame, and the representative luminance value and the histogram data may be read out for each frame period, and the light amount may be adjusted in accordance with the readout.
[0007]
The light amount adjusting means according to the present invention reduces the light amount when halation occurs, and based on the difference between the representative luminance value and the reference luminance value when the representative luminance value is equal to or less than the reference luminance value. Increase the amount of light. For example, when the light source unit has a configuration in which a diaphragm is provided between a light source such as a halogen lamp and an incident end of an optical fiber bundle provided in the videoscope, the light quantity is increased by opening or closing the diaphragm, Decrease. In the case where the light emitting diode is provided at the tip of the video scope, the amount of light is increased or decreased by adjusting the amount of current sent to the light emitting diode.
[0008]
Regarding the light amount reduction, since the light amount is adjusted by detecting the presence or absence of halation instead of using the average luminance value, a subject image without halation can be displayed on a monitor or the like. Further, regarding the increase in the amount of light, since the light amount is adjusted based on the difference between the representative luminance value and the reference luminance value, an appropriate brightness is maintained without darkening the subject image.
[0009]
Considering that halation is never generated, it is preferable that the light amount control means preferentially decreases the light amount regardless of the representative luminance value when halation occurs.
[0010]
When using forceps for treatment or the like, halation is likely to occur. In this case, if the light amount is reduced every time the occurrence of halation is detected, the entire subject image becomes dark. Therefore, it is desirable that the light amount control means decrease and increase the light amount based on the difference between the representative luminance value and the reference luminance value when using forceps.
[0011]
In the endoscope automatic light control device of the present invention, in order to obtain histogram data, histogram processing means for performing histogram processing based on an image signal corresponding to a subject image, and whether halation occurs based on the histogram data A halation detecting means for detecting whether or not, a representative luminance value calculating means for calculating a representative luminance value indicating representative brightness of the subject image based on the image signal, and a representative luminance value based on the representative luminance value. Representative luminance value determining means for determining whether or not the reference luminance value is equal to or less than the reference luminance value shown, and based on the presence / absence of halation, the representative luminance value, and the reference luminance value, the subject image has a suitable brightness And a light amount adjusting means for adjusting the light amount of the light for illuminating at predetermined time intervals, and the light amount adjusting means reduces the light amount when halation occurs. , When the representative luminance value is equal to or lower than the reference luminance value is characterized by increasing the amount of light based on a difference between the reference luminance value with a representative luminance value.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an electronic endoscope apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a block diagram of an electronic endoscope apparatus according to the first embodiment. The electronic endoscope apparatus is an apparatus for performing an examination, an operation, or the like on an internal organ such as a stomach. When the examination or the like is started, a video scope is inserted into the body for photographing an observation site.
[0014]
The electronic endoscope apparatus includes a video scope 50 having a CCD 54 as an image sensor and a processor 10 that processes an image signal sent from the video scope 50, and a monitor 32 ′ that displays a subject image is provided in the processor 10. Connected. The video scope 50 is detachably connected to the processor 10, and a keyboard 34 ′ is connected to the processor 10.
[0015]
The light emitted from the light source lamp 12 enters the incident end 51A of the optical fiber bundle 51 provided in the video scope 50 through a condenser lens (not shown). The optical fiber bundle 51 is an optical fiber that transmits the light emitted from the lamp 12 to the distal end side of the videoscope 50 having the observation site, and the light passing through the optical fiber bundle 51 is emitted from the emission end 51B. Thereby, the observation site S is irradiated with light.
[0016]
The light reflected at the observation site S passes through the objective lens (not shown) and reaches the light receiving surface of the CCD 54, whereby an image of the observation site S is formed on the light receiving surface of the CCD 54. In this embodiment, a single plate simultaneous type is applied as a color imaging method, and yellow (Ye), cyan (Cy), magenta (Mg), and green (G) color elements are checked on the light receiving surface of the CCD. Complementary color filters (not shown) arranged in a line are arranged so as to correspond to the respective pixels on the light receiving surface. In the CCD 54, the image signal of the subject image corresponding to the color passing through the complementary color filter is generated by photoelectric conversion, and the image signal for one frame or one field is sequentially read out at predetermined time intervals according to the color difference line sequential method. As the color television system, for example, the NTSC system is applied, and image signals for one frame (one field) are sequentially read out every 1/30 (1/60) second interval and sent to the processor 10.
[0017]
The signal processing circuit 20 of the processor 10 includes a CCD gain control circuit that controls the gain of the image signal output from the CCD 54, a timing circuit that adjusts the timing (delay time) of reading the image signal, and R, R, G and B gain control circuits for performing G and B gain control, gamma correction circuits for performing gamma correction, color matrix circuits for generating luminance signals, color difference signals, and the like are included (both shown in the figure). Not shown). Various processes are performed on the image signal input to the signal processing circuit 20 in each circuit, and as a result, a video signal is generated. The generated video signal is output to the monitor 32 ′ as a video signal such as an NTSC composite signal, a Y / C separation signal (S video signal), or an RGB separation signal, whereby a subject image is displayed on the monitor 32 ′.
[0018]
A CPU (Central Processing Unit) 24 controls the entire processor 10 and outputs a control signal to each circuit such as a signal processing circuit 20 constituted by an IC chip and stores a program for executing light amount adjustment and the like. ROM (not shown). A data rewritable EEPROM 57 is provided in the video scope 50, and data relating to the characteristics of the video scope 50 is stored in the EEPROM 57 in advance. When the video scope 50 is connected to the processor 10, the data stored in the EEPROM 57 is sent to the processor 10 and stored in the memory 26.
[0019]
A series of panel switches 30 are provided on the front panel of the processor 10, and processing corresponding to an operation on the panel switches 30 is executed. The up switch 30A and the down switch 30B are switches for setting a reference luminance value to be described later. When the operator operates the up switch 30A and the down switch 30B, a signal corresponding to the operation is sent to the CPU 24. A reference value is set based on the transmitted signal. When a key operation is performed to display character information such as patient information on the monitor 32 'on the keyboard 34', a signal corresponding to the operation of the keyboard 34 'is input to the CPU 24, and a CRTC (CRT A control signal is sent to the controller 22. Then, a character signal corresponding to the key operation is output from the CRTC 22 and superimposed on the video signal. In addition, date / time data is read from the RTC (Real Time Clock) 28 by the CPU 24, and a character signal corresponding to the current date / time is output from the CRTC 22.
[0020]
A diaphragm 34 is provided between the incident end 51 </ b> A of the light guide 51 and the light source 12, and the diaphragm 34 is opened and closed by driving the motor 33. The motor 33 is a stepping motor and is driven (rotated) in accordance with a pulse signal sent from the aperture control circuit 32. Therefore, the driving amount of the diaphragm 34, that is, the amount of change in the opening of the diaphragm 34 follows the pulse signal. In the present embodiment, the number of pulses required to drive the diaphragm 34 from fully open to fully closed is 240. In the signal processing circuit 20, a luminance signal for one frame is generated based on the transmitted image signal and is sent to the histogram circuit 23. In the histogram circuit 23, histogram data relating to the brightness of the subject image is generated based on the transmitted luminance signal and output to the CPU 24. A control signal is output to the aperture control circuit 32 based on the histogram data, and the aperture 34 is opened and closed so that the brightness of the subject image is constant. A forceps channel (not shown) for inserting forceps (not shown) used for treatment or the like is formed in the video scope 50, and forceps are inserted as necessary.
[0021]
FIG. 2 is a diagram showing a main routine executed by the CPU 24 in the processor 10.
[0022]
In step S101, initial setting of the CPU 24 and initial setting of variables are performed. In step S102, processing relating to the panel switch 30 is performed, and when a predetermined switch is operated, processing for the switch is executed. In step S103, processing relating to the keyboard 34 'is performed, and when a predetermined key is operated, processing for that key operation is executed.
[0023]
In step S104, clock processing is performed, data corresponding to the date / time is read from the RTC 28, and the date / time is displayed on the monitor 32 ′. In step S105, processing related to the video scope 50 is performed. In step S106, other processing is performed. Steps S102 to S106 are repeatedly executed until the main power supply of the processor 10 is turned off.
[0024]
FIG. 3 is a diagram showing an interrupt routine for executing the automatic dimming process. In the present embodiment, automatic light control processing is performed by interrupting the main routine every 1/30 seconds in accordance with image signal reading for one frame.
[0025]
In step S201, histogram data (see FIG. 4) relating to the brightness of the subject image for one screen is generated in the histogram circuit 23 and read out by the CPU 24. The histogram is sent from the signal processing circuit 20 (FIG. 1) to the histogram circuit 23 (FIG. 1), with the horizontal axis representing the luminance value of each pixel constituting the subject image displayed on the monitor 32 ′. A graph is shown in which the vertical axis represents the number of pixels (frequency) corresponding to each luminance value on the horizontal axis of all pixels constituting the luminance signal for one frame. In the present embodiment, the brightness of the subject image is set to any value in the range of 0 to 255 as the luminance value. When step S201 is executed, the process proceeds to step S202.
[0026]
In step S202, values of a constant vp1 representing the halation occurrence ratio, a variable vp2 representing the high luminance pixel ratio, and a variable vm representing the luminance average value are calculated based on the histogram data. The halation occurrence ratio vp1 indicates the ratio of pixels having a luminance equal to or higher than the halation boundary luminance value (constant CB1) among all the pixels constituting the subject image. The halation boundary luminance value CB1 is a luminance value that is considered to cause halation on the screen of the monitor 32 ′ if it is equal to or greater than this value, and is set to, for example, 227 here (see FIG. 4). The high luminance pixel ratio vp2 indicates the ratio of pixels having a luminance equal to or higher than the high luminance boundary luminance value (variable CB2) among all the pixels constituting the subject image. The high luminance boundary luminance value CB2 is a luminance value that is regarded as high luminance if it is equal to or higher than this value, and is set to 197, for example (see FIG. 4). The average luminance value vm is calculated by dividing the sum of the multipliers of the number of pixels in each luminance value and the luminance value by the total number of pixels in one frame, as shown by the following equation. Here, j represents a luminance value, and nj represents the number of pixels having the luminance value j (frequency).
vm = (Σnj × j) / Σnj (j = 0 to 255) (1)
When step S202 is executed, the process proceeds to step S203.
[0027]
In step S203, it is determined whether or not the calculated halation occurrence rate vp1 is greater than the reference halation rate (constant CP1). The reference halation rate CP1 is a rate that becomes a reference for executing the light amount adjustment. If the halation occurrence rate vp1 is larger than the reference halation rate CP1, the light amount is decreased. Here, the reference halation ratio CP1 is set to 1% in consideration of minimizing the occurrence of halation. That is, the occurrence of halation is detected even if halation occurs in a very small part of the subject image. If it is determined in step S203 that the calculated halation occurrence rate vp1 is greater than the reference halation rate CP1, the process proceeds to step S204.
[0028]
In step S204, a control signal for driving the diaphragm 34 by a predetermined amount is output to the diaphragm control circuit 32 so that the subject image has an appropriate brightness. In the present embodiment, the drive amount of the diaphragm 34 is proportional to the rotation number of the motor 33, and the rotation amount of the motor 33 follows the number of pulses output from the diaphragm control circuit 32. As shown in FIG. 5, in the present embodiment, the number of pulses when the amount of light is reduced is determined from a table T1 showing the correspondence between the number of pulses and the high luminance ratio vp2. That is, the number of pulses, that is, the driving amount of the diaphragm 34 is determined based on the value of the high luminance ratio vp2 calculated in step S202. When step S204 is executed, the process proceeds to step S205.
[0029]
In step S205, the light quantity reduction execution presentation variable vc is set to zero. However, the light quantity reduction execution presentation variable vc is a variable indicating whether or not the light quantity reduction processing has been performed, and is set to 0 when the light quantity reduction is performed, and is set to 1 when the light quantity reduction is not performed. In step S205, the light quantity increase execution presentation variable vc2 is set to 1. The light quantity increase execution presentation variable vc2 is a variable that indicates whether or not the light quantity increase processing has been performed, and is set to 0 when the light quantity increase is performed, and is set to any one of 1 to C2 when it is not performed. Is done. However, the light quantity increase processing counter constant is represented by “C2”. The light quantity increase process counter constant C2 corresponds to a period in which the diaphragm 34 is not driven to prevent hunting after the light quantity is reduced. Here, the light quantity increase process counter constant C2 is set to 6. Therefore, the light quantity increase execution presentation variable vc2 also has a function as a counter that counts the number of interrupts in the interrupt routine so that the diaphragm 34 is not driven immediately after the light quantity is reduced. When step S205 is executed, the interrupt routine ends.
[0030]
On the other hand, if it is determined in step S203 that the calculated halation occurrence rate vp1 is not greater than the reference halation rate CP1, the process proceeds to step S206, where it is determined whether the luminance average value vm is smaller than the reference luminance value CM. . The reference luminance value CM is a luminance value serving as a reference for maintaining the appropriate brightness of the subject image, and is set to 128 here. When it is determined in step S206 that the average luminance value vm is not smaller than the reference luminance value CM, the subject image can be regarded as appropriate brightness, and thus the process proceeds to step S214, where the light quantity increase execution presentation variable vc2 is the light quantity increase processing counter constant C2. Set to a value. When step S214 is executed, the interrupt routine ends.
[0031]
On the other hand, when it is determined in step S206 that the average luminance value vm is smaller than the reference luminance value CM, the process proceeds to step S207, and it is determined whether or not the light quantity reduction execution presentation variable vc is zero. If it is determined that the light quantity reduction execution presentation variable vc is 0, if the diaphragm 34 is driven to increase the light quantity immediately after the diaphragm 34 is driven to reduce the light quantity, the diaphragm 34 may enter a hunting state. From step S213, the diaphragm 34 is not driven. When the light quantity reduction execution presentation variable vc is set to 1 in step S213, the interrupt routine ends.
[0032]
On the other hand, if it is determined in step S207 that the light quantity decrease execution presentation variable vc is not 0, the process proceeds to step S208, and it is determined whether or not the light quantity increase execution presentation variable vc2 is greater than or equal to the value of the light quantity increase processing counter constant C2. The When it is determined that the light quantity increase execution presentation variable vc2 is not greater than or equal to the value of the light quantity increase processing counter constant C2, the process proceeds to step S211, and it is determined whether or not the light quantity increase execution presentation variable vc2 is zero. If it is determined that the light quantity increase execution presentation variable vc2 is not 0, the process proceeds to step S212 without driving the diaphragm 34 in order to prevent hunting of the diaphragm 34. In step S212, 1 is added to the light quantity increase execution presentation variable vc2. Therefore, in this embodiment, the light quantity increase is not executed until “C2-1” times after the light quantity reduction is performed. When step S212 is executed, the interrupt routine ends.
[0033]
On the other hand, if it is determined in step S208 that the light quantity increase execution presentation variable vc2 is greater than or equal to the value of the light quantity increase processing counter constant C2, or if it is determined in step S211 that the light quantity increase execution presentation variable vc2 is 0, the light quantity increase is executed. The process proceeds to step S209. In step S209, a control signal is sent to the diaphragm control circuit 32 based on the difference between the luminance average value vm and the reference luminance value CM so that the diaphragm 34 opens to a predetermined opening. Here, the number of pulses corresponding to the drive amount (variation amount) of the diaphragm 34 is determined based on the table T2 shown in FIG. When step S209 is executed, the process proceeds to step S210, and the light quantity increase execution presentation variable vc2 is set to 0 to indicate that the light quantity has been increased. When step S210 is executed, the interrupt routine ends.
[0034]
Thus, according to the first embodiment, the halation occurrence ratio vp1 and the average luminance value vm are calculated based on the histogram data. When the occurrence of halation is detected from the value of the halation occurrence rate vp1, the diaphragm 34 is closed by a predetermined amount in order to reduce the amount of light. When halation does not occur and the average luminance value vm is smaller than the reference luminance value CM, the diaphragm 34 is opened by a predetermined amount in order to increase the amount of light. Note that the amount of light may be increased in the subsequent step when the average brightness value vm is equal to or smaller than the reference luminance value CM in step 206.
[0035]
Next, a second embodiment will be described. In the second embodiment, the light amount adjustment is performed in consideration of a state where forceps are inserted into the forceps channel in the video scope 50. Other configurations are the same as those in the first embodiment.
[0036]
FIG. 6 is a diagram showing an interrupt routine for executing automatic light control processing in the second embodiment.
[0037]
The execution of steps S301 and S302 is the same as the execution of steps S201 and S202 in FIG. 3, respectively. That is, histogram data is generated, and a halation occurrence ratio vp1, a high luminance pixel ratio vp2, and a luminance average value vm are calculated. When step S302 is executed, the process proceeds to step S303.
[0038]
In step S303, it is determined whether or not the forceps use state variable vf is zero. The forceps use state variable vf is a variable indicating whether or not the forceps are used. The forceps use state variable vf is set to 1 when the forceps are used, and the forceps is used when the forceps is not used. The use state variable vf is set to 0. In the present embodiment, when the operator uses forceps, the keyboard 34 ′ is operated to set use of forceps. Then, the forceps use state variable vf is set to 1 or 0 according to the operation on the keyboard 34 '. When it is determined in step S303 that the forceps use state variable vf is 0, the process proceeds to step S304, and light amount adjustment similar to that in the first embodiment is performed. That is, execution of step S304 is the same as execution of step S203 to step S214. When step S304 is executed, the interrupt routine ends. On the other hand, when it is determined in step S303 that the forceps use state variable vf is not 0, the process proceeds to step S305.
[0039]
In step S305, it is determined whether or not the difference (| vm−CM |) between the average luminance value vm and the reference luminance value CM is larger than the allowable value CA. The allowable value CA indicates an allowable range in which the brightness of the subject image can be regarded as appropriate. If it is determined that the difference between the average luminance value vm and the reference luminance value CM is not larger than the allowable value CA, the interrupt routine is terminated without driving the diaphragm 34. On the other hand, if it is determined that the difference between the luminance average value vm and the reference luminance value CM is larger than the allowable value CA, the process proceeds to step S306 to execute the light amount adjustment.
[0040]
In step S306, it is determined whether or not the average luminance value vm is larger than the reference luminance value CM. If it is determined that the average luminance value vm is larger than the reference luminance value CM, the process proceeds to step S307, and a control signal is sent to the aperture control circuit 32 so that the aperture 34 is closed by a predetermined amount. At this time, the pulse signal corresponding to the driving amount of the diaphragm 34 is calculated based on the table T1 in FIG. On the other hand, if it is determined that the luminance average value vm is not larger than the reference luminance value CM, the process proceeds to step S308, and a control signal is sent to the aperture control circuit 32 so that the aperture 34 is opened by a predetermined amount. At this time, the pulse signal corresponding to the driving amount of the diaphragm 34 is calculated based on the table T2 in FIG. When step S307 or step S308 is executed, the interrupt routine ends.
[0041]
As described above, according to the second embodiment, when the forceps are used, the light amount reduction and the light amount increase are executed based on the difference between the luminance average value vm and the reference luminance value CM.
[0042]
In the first and second embodiments, the average luminance value vm is applied. However, as a representative value indicating the brightness of the subject image, a peak value or the like may be applied instead of the average luminance value.
[0043]
Regarding the configuration for adjusting the amount of light, instead of adjusting the amount of light incident on the optical fiber bundle by opening and closing the aperture, the current supplied to the light emitting diode is controlled in a configuration in which the light emitting diode is provided at the tip of the videoscope. The amount of light applied to the subject may be adjusted by the above. Moreover, you may apply the structure which performs light quantity adjustment mentioned above with respect to the light source device for endoscopes instead of an electronic endoscope apparatus.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to perform light amount adjustment for maintaining the subject image at an appropriate brightness while suppressing the occurrence of halation.
[Brief description of the drawings]
FIG. 1 is a block diagram of an electronic endoscope apparatus according to a first embodiment.
FIG. 2 is a diagram showing a main routine executed by a CPU in the processor.
FIG. 3 is a diagram showing an interrupt routine for executing an automatic dimming processing operation;
FIG. 4 is a diagram showing a histogram relating to the brightness of a subject image.
FIG. 5 is a diagram showing a table relating to pulse number setting for driving a motor.
FIG. 6 is a diagram showing an interrupt routine for executing an automatic light control processing operation in the second embodiment.
[Explanation of symbols]
10 processor
24 CPU
32 Aperture control circuit
33 Motor
34 Iris
50 video scope
54 CCD (Image sensor)
vp1 halation rate
vp2 High luminance pixel ratio
vm Average brightness value (representative brightness value)
CM reference brightness value

Claims (4)

An electronic endoscope apparatus comprising a video scope having an image sensor and a processor to which the video scope is connected,
Histogram processing means for performing histogram processing based on an image signal read from the image sensor in order to obtain histogram data relating to the brightness of the subject image;
Halation detection means for detecting whether halation has occurred based on the histogram data;
Representative luminance value calculating means for calculating a representative luminance value indicating the average brightness of the subject image based on the image signal;
Representative luminance value determining means for determining whether or not the representative luminance value is equal to or lower than a reference luminance value indicating a representative representative luminance value;
Based on the presence / absence of the halation detected by the halation detection means, the representative luminance value, and the reference luminance value, a predetermined amount of light for illuminating the subject is set so that the subject image has an appropriate brightness And a light amount adjusting means for adjusting every time interval,
The light amount adjusting means reduces the light amount when halation occurs, and when the halation does not occur and the representative luminance value is smaller than the reference luminance value, the representative luminance value and the The amount of light is increased based on the difference from the reference luminance value, but no halation is generated, and when the representative luminance value is equal to or greater than the reference luminance value, the increase / decrease in the amount of light is not adjusted. An electronic endoscope device. The electronic endoscope apparatus according to claim 1, wherein the light amount adjusting unit preferentially reduces the light amount regardless of the representative luminance value when halation occurs. 2. The electronic endoscope apparatus according to claim 1, wherein the light amount adjusting unit decreases and increases the light amount based on a difference between the representative luminance value and the reference luminance value when using forceps. Histogram processing means for performing histogram processing based on an image signal corresponding to the subject image in order to obtain histogram data relating to the brightness of the subject image;
Halation detection means for detecting whether halation has occurred based on the histogram data;
Representative luminance value calculating means for calculating a representative luminance value indicating the average brightness of the subject image based on the image signal;
Representative luminance value determining means for determining whether or not the representative luminance value is equal to or lower than a reference luminance value indicating a representative representative luminance value;
Based on the presence / absence of the halation detected by the halation detection means, the representative luminance value, and the reference luminance value, a predetermined amount of light for illuminating the subject is set so that the subject image has an appropriate brightness And a light amount adjusting means for adjusting every time interval,
The light amount adjusting means reduces the light amount when halation occurs, and when the halation does not occur and the representative luminance value is smaller than the reference luminance value, the representative luminance value and the The amount of light is increased based on the difference from the reference luminance value, but no halation is generated, and when the representative luminance value is equal to or greater than the reference luminance value, the increase / decrease in the amount of light is not adjusted. Automatic dimming device for endoscope.

Images