JP2003284682A - Automatic light adjustment device for endoscope and endoscopic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the quantity of light so as to keep a subject in a proper brightness while inhibiting the occurrence of halation. <P>SOLUTION: The electronic endoscope equipped with a video scope 50 having CCD 54 and a processor 10 has a histogram circuit 23, a light source lamp 12 and a diaphragm 34 set up between the light source lamp 12 and an edge of an incidence 51A of an optical fiber bundle 51. The hitstogram circuit 23 produces histogram data from image signals in accordance with the subject image. A frequency of halation and an average value of luminance based on the histogram data are calculated before the presence and absence of the halation occurrence are detected; the diaphragm 34 is closed so as to reduce the quantity of light to be illuminated on the subject when the halation exists. The diaphragm 34 is opened, however, to increase the quantity of light when the halation does not exist and an average value of luminance is lower than a reference value of luminance. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope apparatus capable of observing an image of a predetermined portion by inserting an endoscope (scope) into an organ such as a stomach, and more particularly to the brightness of a subject image. The present invention relates to automatic light control for adjusting the amount of illumination light applied to an observation site so that the light intensity is constant.

[0002]

2. Description of the Related Art In a conventional endoscope apparatus, the brightness of a subject (luminance of the subject) is determined based on an image signal corresponding to a subject image.
Is detected, and the light amount of the illumination light is adjusted by comparing with a reference value indicating appropriate brightness of the subject. If the brightness value is larger than the reference value, the diaphragm is closed to reduce the light amount, and conversely, if the brightness value is smaller than the reference value, the diaphragm is opened to increase the light amount. As a 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,
Alternatively, the peak value representing the maximum brightness is applied, and the operator can set the level of the reference value by operating the switch provided in the processor.

[0003]

When the light amount is adjusted by comparing the average luminance value with the reference value, halation (a state in which a part of the subject image is too bright and appears white) is likely to occur. It interferes with the treatment. On the other hand, when the light intensity is adjusted by comparing the peak brightness value with the reference value, halation can be suppressed, but the observed subject image tends to be dark as a whole. 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 while operating the endoscope. For this reason, it becomes difficult to always maintain the brightness of the subject at an appropriate brightness while performing a treatment or the like.

Therefore, it is an object of the present invention to provide an electronic endoscope apparatus and an automatic light control apparatus for an endoscope, which can adjust the light quantity for keeping the image of a subject at an appropriate brightness while suppressing the occurrence of halation. To do.

[0005]

An electronic endoscope apparatus according to the present invention is an electronic endoscope apparatus including a videoscope having an image pickup device and a processor to which the videoscope is connected. The image signal read from is processed and a video signal is output to a monitor or the like. In order to obtain histogram data, the electronic endoscope apparatus of the present invention determines whether or not halation has occurred based on the histogram processing means for performing histogram processing based on the image signal read from the image sensor and the histogram data. Halation detection means for detecting. For example, based on the histogram data, the halation occurrence ratio indicating the ratio of the number of high-luminance pixels to the total number of pixels forming the subject image is calculated, and it is determined whether the halation occurrence ratio is a value other than 0. Halation may be detected by this. The brightness value indicating the brightness of the subject image is set to any value in the range of 0 to 255 as the brightness level, for example. The high-brightness pixel is a pixel having a brightness value equal to or higher than the halation boundary brightness value, and the halation boundary brightness value is a brightness value serving as a threshold value (boundary value) regarded as occurrence of halation. When the brightness value is in the range of 0 to 255, it is set to any value of approximately 200 to 230. Alternatively, it may be set to any value of 220 to 230.

Further, the electronic endoscope apparatus has a representative brightness value calculating means for calculating a representative brightness value indicating a typical brightness of a subject image based on the image signal, and the representative brightness value is equal to or less than the reference brightness value. And a representative luminance value discriminating means for discriminating whether or not. As the representative brightness value, for example, a brightness average value indicating the average brightness of the subject image or a peak brightness value that is the maximum brightness value in the entire subject image may be applied. The reference brightness value indicates a representative brightness value that serves as a reference for determining whether or not to adjust the light amount. For example, when the representative brightness value is a brightness average value, within the range that the brightness value can take. The brightness value near the middle may be used as the reference brightness value. Regarding the light amount adjustment, the electronic endoscope apparatus includes a light amount adjusting unit that adjusts the light amount of the light that illuminates the subject so that the brightness of the subject image displayed on a monitor or the like becomes constant, and at a predetermined time interval. Adjust the light intensity. For example, it suffices to perform it in accordance with the read period of the image signal for one frame, and read the representative luminance value and the histogram data for each frame period,
The light amount may be adjusted accordingly.

The light amount adjusting means according to the present invention reduces the light amount when halation occurs, and when the representative luminance value is less than or equal to the reference luminance value, the difference between the representative luminance value and the reference luminance value. The amount of light is increased based on. For example, in the case where the light source unit has a diaphragm provided between a light source such as a halogen lamp and the incident end of an optical fiber bundle provided in the videoscope, the light quantity can be increased or decreased by opening and closing the diaphragm. Reduce. Further, in the case where the light emitting diode is provided at the tip of the videoscope, the amount of light is increased or decreased by adjusting the amount of current sent to the light emitting diode.

With respect to the reduction of the light quantity, the light quantity is adjusted by detecting the presence or absence of halation instead of using the average luminance value, so that a subject image without halation can be displayed on a monitor or the like. With respect to the increase in the light amount, the light amount is adjusted based on the difference between the representative luminance value and the reference luminance value, so that the subject image does not become dark and appropriate brightness is maintained.

Considering that the halation is never generated, it is desirable that the light amount control means preferentially reduce the light amount regardless of the representative luminance value when the halation occurs.

When forceps are used for treatment, halation is likely to occur. In this case, if the light amount is reduced each time the occurrence of halation is detected, the entire subject image becomes dark. Therefore, when using forceps, it is desirable that the light amount control means decrease or increase the light amount based on the difference between the representative luminance value and the reference luminance value.

In order to obtain histogram data, the automatic light control device for an endoscope of the present invention produces a halation based on the histogram processing means for performing the histogram processing based on the image signal corresponding to the subject image and the histogram data. Halation detection means for detecting whether or not
Representative brightness value calculating means for calculating a representative brightness value representing a typical brightness of the subject image based on the image signal, and whether the representative brightness value is equal to or lower than a reference brightness value representing a reference representative brightness value. Based on the representative luminance value discriminating means for discriminating between the presence and absence of halation, the representative luminance value and the reference luminance value, the light amount of the light illuminating the subject is adjusted to a predetermined time so that the brightness of the subject image becomes appropriate brightness. A light amount adjusting means for adjusting each interval is provided, and the light amount adjusting means reduces the light amount when halation occurs, and when the representative luminance value is equal to or less than the reference luminance value, the representative luminance value and the reference The feature is that the amount of light is increased based on the difference from the brightness value.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An electronic endoscope apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an electronic endoscope apparatus according to the first embodiment. The electronic endoscope device is a device for performing an inspection, an operation, or the like on an organ in the body such as the stomach, and when the inspection or the like is started, a videoscope is inserted into the body for photographing an observation site.

In the electronic endoscope apparatus, CC is used as an image pickup device.
Videoscope 50 having D54, and processor 1 for processing image signals sent from the videoscope 50
0 and a monitor 32 ′ for displaying a subject image is connected to the processor 10. The video scope 50 is detachably connected to the processor 10, and a keyboard 34 'is connected to the processor 10.

The light emitted from the light source lamp 12 is incident on an incident end 51A of an optical fiber bundle 51 provided in the videoscope 10 via 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 tip side of the videoscope 50 having the observation site, and the light that has passed through the optical fiber bundle 51 is emitted from the emission end 51B. As a result, the observation site S is irradiated with light.

The light reflected at the observation site S reaches the light receiving surface of the CCD 54 through an objective lens (not shown), and an image of the observation site S is formed on the light receiving surface of the CCD 54. In the present embodiment, the single-plate simultaneous type is applied as a color imaging method, and yellow (Ye), cyan (Cy), magenta (Mg), and green (G) color elements are in a checkered pattern 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, an image signal of a subject image corresponding to a color passing through a complementary color filter is generated by photoelectric conversion, and an 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 a color television system, for example, N
The TSC system is applied, and image signals for one frame (one field) are sequentially read out at intervals of 1/30 (1/60) seconds and sent to the processor 10.

The signal processing circuit 20 of the processor 10 includes:
A CCD gain control circuit for controlling the gain of the image signal output from the CCD 54, a timing circuit for adjusting the timing (delay time) of reading the image signal, an R for controlling the R, G, B gains for white balance adjustment, A G and B gain control circuit, a gamma correction circuit for performing gamma correction, a color matrix circuit for generating a luminance signal, a color difference signal, and the like are included (all 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 separated signal (S video signal), an RGB separated signal, etc., whereby a subject image is displayed on the monitor 32'.

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 including an IC chip, and a ROM (not shown) storing a program for performing light amount adjustment and the like. Have. The data rewritable EEPROM 57 is provided in the video scope 50.
Is provided, 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.

A series of panel switches 30 are provided on the front panel of the processor 10, and processing corresponding to the operation on the panel switches 30 is executed. The up switch 30A and the down switch 30B are switches for setting a reference brightness value, which will 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 2
Sent to 4. A reference value is set based on the signal sent. When a key operation is performed on the keyboard 34 'to display character information such as patient information on the monitor 32', a signal corresponding to the operation of the keyboard 34 'is changed to C.
It is input to PU24 and CRTC (CR
A control signal is sent to the T controller) 22. And
A character signal corresponding to a key operation is output from the CRTC 22 and superimposed on a video signal. Further, the date and time data is read from the RTC (Real Time Clock) 28 by the CPU 24, and the character signal according to the current date and time is output from the CRTC 22.

Incident end 51A of light guide 51 and light source 1
2 is provided with a diaphragm 34 for adjusting the amount of light irradiated to the subject S, and the diaphragm 34 is a motor 3
It is opened and closed by the drive of 3. The motor 33 is a stepping motor and is driven (rotated) according to the pulse signal sent from the aperture control circuit 32. Therefore, the drive amount of the diaphragm 34, that is, the change amount of the opening degree 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. The signal processing circuit 20 generates a luminance signal for one frame based on the image signal sent, and sends it to the histogram circuit 23. The histogram circuit 23 generates histogram data regarding the brightness of the subject image based on the transmitted luminance signal, and outputs the histogram data to the CPU 24. Then, 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 becomes constant. In the videoscope 50,
A forceps channel (not shown) for inserting forceps (not shown) used in treatment or the like is formed, and forceps is inserted as necessary.

FIG. 2 is a diagram showing a main routine executed by the CPU 24 in the processor 10.

In step S101, the CPU 24 and the variables are initialized. In step S102, a process regarding the panel switch 30 is performed, and when a predetermined switch is operated, the process for the switch is performed. In step S103, the keyboard 34 '
Is performed and a predetermined key is operated,
The process corresponding to the key operation is executed.

In step S104, clock processing is performed, data corresponding to the date and time is read from the RTC 28, and the date and time are displayed on the monitor 32 '. In step S105, processing relating to the video scope 50 is performed. Then, 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.

FIG. 3 is a diagram showing an interrupt routine for executing automatic light control processing. In this embodiment, the automatic dimming process is performed by interrupting the main routine every 1/30 seconds in accordance with the reading of the image signal for one frame.

In step S201, the histogram circuit 23 generates data of a histogram (see FIG. 4) relating to the brightness of the subject image for one screen, and the CPU 24
Read by. Histogram monitor 32 '
The luminance signal of one frame sent from the signal processing circuit 20 (FIG. 1) to the histogram circuit 23 (FIG. 1) with the horizontal axis representing a possible luminance value of each pixel forming the subject image displayed in FIG. 4 is a graph in which the vertical axis represents the number (frequency) of pixels corresponding to each luminance value on the horizontal axis of all the pixels constituting the. In the present embodiment, the brightness of the subject image is set to any value in the range of 0 to 255 as the brightness value.
When step S201 is executed, the process proceeds to step S202.

In step S202, the variable vp representing the halation occurrence rate is calculated based on the histogram data.
1, each value of the variable vp2 representing the high-luminance pixel ratio and the variable vm representing the average luminance value is calculated. The halation occurrence rate vp1 indicates the proportion of pixels having a luminance equal to or higher than the halation boundary luminance value (variable CB1) among all the pixels forming the subject image. Halation boundary brightness value CB
1 is a luminance value that is considered to cause halation on the screen of the monitor 32 'if it is equal to or larger than this value,
Here, it is set to, for example, 227 (see FIG. 4). The high-brightness pixel ratio vp2 indicates the ratio of pixels having a brightness equal to or higher than the high-brightness boundary brightness value (variable CB2) among all the pixels forming the subject image. High brightness boundary brightness value CB2
Is a luminance value that is considered to be high luminance if it is greater than or equal to this value, and is set to 197 here (see FIG. 4). The brightness average value vm is calculated by dividing the sum of the number of pixels at each brightness value and the multiplier of the brightness value by the total number of pixels in one frame, as shown in the following equation. However, j indicates a brightness value, and nj indicates the number (frequency) of pixels having the brightness value j. vm = (Σnj × j) / Σnj (j = 0 to 255) (1) When step S202 is executed, the process proceeds to step S203.

In step S203, the calculated halation occurrence rate vp1 is the reference halation rate (variable C
It is determined whether it is larger than P1). The reference halation ratio CP1 is a ratio serving as a reference for executing the light amount adjustment, and if the halation occurrence ratio vp1 is larger than the reference halation ratio CP1, the light amount is reduced.
Here, the reference halation ratio CP1 is set to 1% in consideration of maximizing 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. When it is determined in step S203 that the calculated halation occurrence rate vp1 is larger than the reference halation rate CP1, the process proceeds to step S204.

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 this embodiment, the driving amount of the diaphragm 34 is proportional to the rotation speed of the motor 33, and the rotation amount of the motor 33 is proportional to the rotation amount of the motor 33.
2 according to the number of pulses output. As shown in FIG.
In the present embodiment, the number of pulses when the light amount is reduced is determined from the 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.

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 it is not performed. Furthermore, step S
At 205, the light amount increase execution presentation variable vc2 is set to 1. The light amount increase execution presentation variable vc2 is a variable indicating whether or not the process of increasing the light amount is performed, and is set to 0 when the light amount increase is performed, and is set to any of 1 to C2 when the light amount increase processing is not performed. To be done. However, the light amount increase processing counter constant is represented by "C2". Light amount increase processing counter constant C2
Corresponds to a period in which the diaphragm 34 is not driven to prevent hunting after the light amount is reduced, and the light amount increasing process counter constant C2 is set to 6 here. Therefore, the light amount increase execution presentation variable vc2 also has a function as a counter that counts the number of interrupts of the interrupt routine so that the diaphragm 34 is not driven immediately after the light amount is reduced. When step S205 is executed, the interrupt routine ends.

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, step S203.
In 206, it is determined whether the average brightness value vm is smaller than the reference brightness value CM. The reference brightness value CM is a reference brightness value for maintaining the proper brightness of the subject image, and is set to 128 here. Step S20
If it is determined in 6 that the average brightness value vm is not smaller than the reference brightness value CM, the subject image can be regarded as appropriate brightness, so the process proceeds to step S214, and the light amount increase execution presentation variable vc2 is the value of the light amount increase processing counter constant C2. Is set to. When step S214 is executed, the interrupt routine ends.

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 the light amount reduction execution presentation variable v
It is determined whether or not c is 0. When 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 decrease the light quantity, the diaphragm 34 may be in a hunting state. From step S without driving the diaphragm 34
Proceed to 213. When the light amount reduction execution presentation variable vc is set to 1 in step S213, the interrupt routine ends.

On the other hand, if it is determined in step S207 that the light amount decrease execution presentation variable vc is not 0, the process proceeds to step S208, and it is determined whether or not the light amount increase execution presentation variable vc2 is equal to or larger than the light amount increase processing counter constant C2. Is judged. When it is determined that the light quantity increase execution presentation variable vc2 is not greater than or equal to the light quantity increase processing counter constant C2,
In step S211, the light amount increase execution presentation variable vc2
Is determined to be 0 or not. When it is determined that the light amount 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. Then, in step S212, 1 is added to the light amount increase execution presentation variable vc2. Therefore, in the present embodiment, “C2-
Up to "1" times, the light amount increase is not executed. Step S21
When 2 is executed, the interrupt routine ends.

On the other hand, if it is determined in step S208 that the light quantity increase execution presentation variable vc2 is equal to or greater than the light quantity increase processing counter constant C2, or in step S211 that the light quantity increase execution presentation variable vc2 is 0,
In order to increase the light amount, the process proceeds to step S209. In step S209, a control signal is sent to the aperture control circuit 32 based on the difference between the average brightness value vm and the reference brightness value CM so that the aperture 34 opens to a predetermined opening. Here, the number of pulses according 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 amount increase execution presentation variable vc2 is set to 0 to indicate that the light amount has been increased. When step S210 is executed, the interrupt routine ends.

As described above, according to the first embodiment, the halation occurrence rate vp is calculated based on the histogram data.
1, the brightness average value vm is calculated. 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 to reduce the light amount. When halation does not occur and the average brightness value vm is smaller than the reference brightness value CM, the diaphragm 34 is opened by a predetermined amount to increase the light amount. Note that, when the average brightness value vm is equal to or smaller than the reference brightness value CM in step 206, the light amount may be increased in the subsequent step.

Next, a second embodiment will be described.
In the second embodiment, the light amount is adjusted in consideration of the state in which the forceps are inserted in the forceps channel in the videoscope 50. Other configurations are the same as those in the first embodiment.

FIG. 6 is a diagram showing an interrupt routine for executing the automatic light control processing in the second embodiment.

The execution of steps S301 and S302 is the same as the execution of steps S201 and S202 of FIG. 3, respectively. That is, the histogram data is generated, and the halation occurrence rate vp1, the high luminance pixel rate vp2, and the luminance average value vm are calculated. When step S302 is executed, the process proceeds to step S303.

In step S303, it is determined whether the forceps use state variable vf is 0 or not. The forceps use state variable vf is a variable indicating whether or not forceps are used, and when the forceps are used, the forceps use state variable vf is 1.
Is set to 0, and the forceps use state variable vf is set to 0 when the forceps are not used. In this embodiment, when the operator uses forceps, the keyboard 34 ′ is operated to set the 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 usage state variable vf is 0, the process proceeds to step S304, and the same light amount adjustment as in the first embodiment is performed. That is, the execution of step S304 is
This is the same as the execution of steps S203 to S214. When step S304 is executed, the interrupt routine ends. On the other hand, when it is determined that the forceps use state variable vf is not 0 in step S303, the process proceeds to step S305.

In step S305, the difference (| vm-CM |) between the average luminance value vm and the reference luminance value CM is the allowable value CA.
It is determined whether or not it is greater than. The allowable value CA indicates an allowable range in which the brightness of the subject image can be considered to be appropriate. When it is determined that the difference between the average brightness value vm and the reference brightness value CM is not larger than the allowable value CA, the interrupt routine ends without driving the diaphragm 34. On the other hand, when it is determined that the difference between the average brightness value vm and the reference brightness value CM is larger than the allowable value CA, the process proceeds to step S306 to execute the light amount adjustment.

In step S306, it is determined whether the average brightness value vm is larger than the reference brightness value CM. When it is determined that the average brightness value vm is larger than the reference brightness 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
It is calculated based on the table T1 in FIG. On the other hand, when it is determined that the average brightness value vm is not larger than the reference brightness 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 opens by a predetermined amount. At this time, the pulse signal corresponding to the drive 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.

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 average luminance value vm and the reference luminance value CM.

Although the average luminance value vm is applied in the first and second embodiments, a peak value or the like may be applied instead of the average luminance value as a representative value indicating the brightness of the subject image. Good.

Regarding the structure for adjusting the light amount, instead of adjusting the light amount of the light incident on the optical fiber bundle by opening and closing the diaphragm, in the structure in which the light emitting diode is provided at the tip of the videoscope, the current supplied to the light emitting diode is changed. You may adjust the light quantity of the light with which a to-be-photographed object is irradiated by controlling. Also, instead of the electronic endoscope device,
You may apply the structure which performs the above-mentioned light amount adjustment with respect to the light source device for endoscopes.

[0044]

As described above, according to the present invention, it is possible to perform the light amount adjustment for keeping the subject image at an appropriate brightness while suppressing the occurrence of halation.

[Brief description of 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 a processor.

FIG. 3 is a diagram showing an interrupt routine for executing an automatic light adjustment 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 view showing an interrupt routine for executing an automatic light adjustment processing operation according to the second embodiment.

[Explanation of symbols]

10 processors 24 CPU 32 Aperture control circuit 33 motor 34 Iris 50 video scope 54 CCD (imaging device) vp1 halation rate vp2 High brightness pixel ratio vm average brightness value (representative brightness value) CM reference brightness value

[Procedure amendment]

[Submission date] November 29, 2002 (2002.11.
29)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The light emitted from the light source lamp 12 is incident on an incident end 51A of an optical fiber bundle 51 provided in the videoscope 50 via 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 tip side of the videoscope 50 having the observation site, and the light that has passed through the optical fiber bundle 51 is emitted from the emission end 51B. As a result, the observation site S is irradiated with light.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

In step S202, a constant vp representing the halation occurrence rate is calculated based on the histogram data.
1, each value of the variable vp2 representing the high-luminance pixel ratio and the variable vm representing the average luminance value is calculated. The halation occurrence rate vp1 indicates the proportion of pixels having a luminance equal to or higher than the halation boundary luminance value (constant CB1) among all the pixels forming the subject image. Halation boundary brightness value CB
1 is a luminance value that is considered to cause halation on the screen of the monitor 32 'if it is equal to or larger than this value,
Here, it is set to, for example, 227 (see FIG. 4). The high-brightness pixel ratio vp2 indicates the ratio of pixels having a brightness equal to or higher than the high-brightness boundary brightness value (variable CB2) among all the pixels forming the subject image. High brightness boundary brightness value CB2
Is a luminance value that is considered to be high luminance if it is greater than or equal to this value, and is set to 197 here (see FIG. 4). The brightness average value vm is calculated by dividing the sum of the number of pixels at each brightness value and the multiplier of the brightness value by the total number of pixels in one frame, as shown in the following equation. However, j indicates a brightness value, and nj indicates the number (frequency) of pixels having the brightness value j. vm = (Σnj × j) / Σnj (j = 0 to 255) ... (1) When step S202 is executed, the process proceeds to step S203.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

In step S203, the calculated halation occurrence rate vp1 is the reference halation rate (constant C
It is determined whether it is larger than P1). The reference halation ratio CP1 is a ratio serving as a reference for executing the light amount adjustment, and if the halation occurrence ratio vp1 is larger than the reference halation ratio CP1, the light amount is reduced.
Here, the reference halation ratio CP1 is set to 1% in consideration of maximizing 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. When it is determined in step S203 that the calculated halation occurrence rate vp1 is larger than the reference halation rate CP1, the process proceeds to step S204.

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Claims (4)

[Claims] 1. An electronic endoscope apparatus comprising a videoscope having an image pickup device and a processor to which the videoscope is connected, wherein the electronic endoscope device is read from the image pickup device in order to obtain histogram data relating to the brightness of a subject image. Histogram processing means for performing histogram processing based on the image signal, halation detection means for detecting whether or not halation is occurring based on the histogram data, and a representative image of a subject image based on the image signal. Representative brightness value calculating means for calculating a representative brightness value indicating the brightness, and a representative brightness value determining means for determining whether or not the representative brightness value is equal to or less than a reference brightness value indicating a standard representative brightness value. The presence or absence of the halation detected by the halation detection means, the representative luminance value and the reference luminance value Based on the light intensity adjusting means for adjusting the light intensity of the light for illuminating the subject at predetermined time intervals so that the brightness of the subject image becomes appropriate brightness, and the light intensity adjusting means generates halation. Decrease the amount of light,
When the representative brightness value is less than or equal to the reference brightness value,
An electronic endoscope apparatus, wherein the amount of light is increased based on a difference between the representative luminance value and the reference luminance value. 2. The electronic endoscope apparatus according to claim 1, wherein the light amount control means preferentially reduces the light amount regardless of the representative luminance value when halation occurs. 3. When the light quantity control means uses forceps,
The light amount is decreased or increased based on a difference between the representative brightness value and the reference brightness value.
The electronic endoscope apparatus according to item 1. 4. Histogram processing means for performing histogram processing based on an image signal corresponding to the subject image to obtain histogram data relating to the brightness of the subject image, and whether halation has occurred based on the histogram data. Halation detection means for detecting whether or not, a representative luminance value calculation means for calculating a representative luminance value indicating a representative brightness of the subject image based on the image signal, and a representative luminance value with the representative luminance value as a reference Based on the representative luminance value discriminating means for discriminating whether or not it is less than or equal to the reference luminance value, the presence or absence of the halation detected by the halation detecting means, and the representative luminance value and the reference luminance value. A light intensity adjustment hand that adjusts the light intensity of the light that illuminates the subject so that the brightness of the image is appropriate. With the door, the light amount adjusting means decreases the amount of light when the halation occurs,
When the representative brightness value is less than or equal to the reference brightness value,
An automatic light control device for an endoscope, wherein the light amount is increased based on a difference between the representative brightness value and the reference brightness value.