JPH01279689A - Color dislocation preventing device - Google Patents

Abstract

PURPOSE:To easily obtain a still picture having the small quantity of color dislocation with a simple configuration by detecting the picture having the smallest quantity of the color dislocation out of either plural frames or plural field pictures recorded in a recording means by a picture staticizing instruction. CONSTITUTION:The quantity of the color dislocation in the whole of a picture can be obtained by extracting only picture element signals, the outputs of which from a subtracter 45 become approximately 0, at a window comparator 50 and executing integration by an integrator (3)51 for the whole of the picture. Consequently, the output of the integrator (3)51 indicates the quantity of the color dislocation. In order or detect the picture in which the output of the integrator (3)51 indicating the quantity of the color dislocation becomes the minimum, the output of the integrator (3)51 is digitized by an A/D converter 52 and inputted to a comparator 54. Thereafter, the respective quantities of the color dislocations in five pictures are successively compared, and the value of the integrator (3)51 obtained when the picture is the one having the minimum color dislocation is digitized and recorded in a register 53 at the end. Further, a timing control circuit 55 outputs a picture memory number corresponding to the picture having the minimum quantity of the color dislocation based on the contents of the register 53.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for preventing color shift of still images in an endoscope imaging device using a color sequential illumination method.

[Conventional technology]

In recent years, solid-state imaging devices such as CCDs have been installed at the tip of endoscopes.
An endoscopic imaging device has been developed that sequentially illuminates the inside of a body cavity with three colors of light: red, green, and blue, takes color images of the inside of the body cavity, and performs diagnosis based on the color image displayed on a monitor device. . To capture one color image using this method, it is necessary to capture component images of three colors, which takes time and tends to cause color shift in the image due to subject movement or camera shake.

As a means to prevent this color shift, Japanese Patent Application Laid-Open No. 1983-71790 filed by the present applicant discloses a means for detecting color shift in images based on the difference between images taken at different times by an imaging means. It has been proposed that the imaging speed of the imaging means is controlled according to the output of the detection means. According to this method, the operating speed of the imaging means changes depending on the operating speed of the subject, and it is possible to prevent color shift from occurring even in the case of a fast-moving subject.

[Problem to be solved by the invention]

By the way, the color shift prevention means in the endoscopic imaging device proposed in the above publication is designed to prevent color shift in moving images, and when observing still images on a monitor device, conventionally, endoscopic imaging When a static instruction is given to the device, the imaging means is unconditionally static based on the instruction to obtain a still image. Therefore, if a still instruction is given at a time when the positions of the subject and the endoscope tip are moving relative to each other, color shift will occur in the still image. This color shift makes it difficult to see the original image of the subject, so there is a risk that the observer may miss a lesion or the like.

In order to obtain a still image without color shift, there is a problem in that a complicated operation of repeating a freeze instruction and a freeze release is required until a still image without color shift is obtained. In addition, when a color shift occurs in a still image, a method has been proposed in which the color shift is corrected using image processing to remove the color shift, but this method not only requires large-scale equipment but also cannot correct the peripheral areas of the image. There were drawbacks.

The present invention has been made in order to solve the above-mentioned problems when obtaining still images using conventional endoscopic imaging devices. An object of the present invention is to provide a color shift prevention device in a mirror imaging device.

[Means and operations for solving the problem] In order to solve the above-mentioned problems, the present invention provides an image stilling instruction means, a means for recording a plurality of frames or field images, and an image stilling instruction means for recording a plurality of frames or field images. A color shift prevention device in an endoscope imaging device using a color sequential illumination method, comprising means for detecting an image with the smallest amount of color shift among a plurality of frame or field images recorded in the recording means according to an instruction. It constitutes.

The subject of an endoscope is mainly a living body, and the subject often moves due to the subject's heartbeat and breathing, but both heartbeat and breathing have cycles, and at certain times the subject will either stand still or move. becomes very small. Then, almost no color shift occurs in the photographed image at this point. Therefore, when multiple frame or field images are recorded, there is a very high possibility that some of them include images with almost no color shift, and the image with the least amount of color shift is detected. By selectively displaying, a still image with less color shift can be easily obtained. This eliminates the need for complicated operations of repeatedly instructing and releasing the stillness, and as a result, the examination time can be shortened and the patient's pain can be alleviated.

〔Example〕

Examples will be described below. FIG. 1 is a block diagram showing an embodiment of a color misregistration prevention device in an endoscope imaging device according to the present invention. In the figure, ■ is an electronic endoscope, and an objective lens 2 is disposed at the tip thereof, and an image pickup element 3 made of a COD or the like is provided at the imaging position. Reference numeral 4 denotes a light guide made of glass fiber or the like, which is used to introduce illumination light into the living body.

Reference numeral 5 denotes a color filter disk provided with red, green, and blue transmission filters, which is rotatably arranged opposite to one end surface of the light guide 4, and is connected to and driven by a motor 6. It has become.

Reference numeral 7 denotes an illumination lamp composed of a xenon lamp or the like, and is connected to a lamp drive circuit 8. 9 is a condensing lens,
It is arranged at a position where the light emitted from the lamp 7 is focused on one end surface of the light guide 4 via the color filter disk 5.

Reference numeral 10 denotes an image stilling switch, which is provided in the operation section of the electronic endoscope 1 and connected to an image stilling control circuit 11. Reference numeral 12 denotes a video circuit including a drive circuit for an image sensor such as a CCD, a video amplifier, etc., to which the image sensor 3 is connected. The output of the video circuit 12 is connected to an A/D converter 13, and the output of the A/D converter 13 is connected to a common terminal of a changeover switch 14 formed of a semiconductor switch or the like. Each switching terminal of the changeover switch 14 is connected to an image memory (r) 15 composed of a semiconductor memory or the like. Image memory (g) 16° image memory (bH7) are connected to each other.

Image memory (r)15. Each output terminal of the image memory (gH6, image memory (bH7) is further connected to an image memory input switch (r) 18.Image memory person Kasuinochi (g)
19. Image memories (R1-R5) 21 to 251 image memories (Gl
~G5) 26~305 Image memory (Bl~B5) 31~
It is connected to 35. Image memory (R1-R5) 21
Each output end of ~25 is an image memory output inch (r) 3
6 to the D/A converter (R) 37, and each output terminal of the image memories (Gl to G5) 26 to 30 is connected to the D/A converter (R) 37 via the image memory output switch (g) 3B. (
G) 39, and further image memory (Bl-85) 31~
Each output end of 35 is an image memory output inch (b) 40
are respectively connected to a D/A converter (B) 41 via.

The R (red) image signal output from the D/A converter 37 is input to the R input terminal of the color monitor 42 .

On the other hand, the G (green) image signal output from the D/A converter 39 is input to the G input terminal of the color monitor 42 and the color shift comparison means 43. Similarly, the B (blue) image signal output from the D/A converter 41 is sent to the color monitor 42.
and the color shift comparison means 43. The output of the color shift comparison means 43 is sent to the image selection control circuit 44.
The output terminal of the image selection control circuit 44 is connected to the image memory output switch (r, g, b).
36.38.40(7) Connected to each control input terminal.

Next, the operation of the color misregistration prevention device in the endoscopic imaging device configured as described above will be explained.

The white light emitted from the lamp 7 passes through the color filter disk 5 which is rotationally driven by the motor 6, and becomes sequential color light of R, C; and H, and is transmitted to the electronic endoscope 1.
The light is incident on one end face of the light guide 4. The color sequential light incident on the end surface of the light guide 4 is transmitted within the light guide 4, reaches the tip of the electronic endoscope 1, and is emitted from the other end surface of the light guide 4. The emitted color sequential light illuminates a subject such as the stomach wall, and an image of the subject is formed on an image sensor 3 by an objective lens 2. The image sensor 3 is a video circuit 12
and its output is driven by the video circuit 12
is converted into a video signal by

The output of the video circuit 12 is digitized by the A/D converter 13, and the digital image data is stored in the image memory (r) 15° while being switched for each R, G, and B component image data by the changeover switch 14. Memory (g
)16. Each image is input and recorded in the image memory (b) 17. The changeover switch 14 is configured to be sequentially switched in synchronization with the rotation of the color filter disc 5 in accordance with the color of the color-sequential light.

Next, image memory (r) 15. Each image data recorded in the image memory (g) 16° and image memory (b) 17 is stored in the image memory (r, g, b) 18.1
9. Via 20, the image memory (R1) 21. Image memory (G1)26. The image is transferred to the image memory (Bl) 31 at high speed.

This transfer operation is performed using the synchronization signal period of the television. Image memory (R1) 2L image memory (G
l)26. The image data transferred to the image memory (Bl) 31 is read out in synchronization with the synchronization signal of the television, and is read out by the image memory output switch (r, g).

b) D/A converter (R) 3 via 36.38.40
7. D/A converter (G) 39. D/A converter (B)
41, the signal is converted into an analog signal and displayed on a color monitor 42. Normally, the above transfer is performed frame by frame, so a moving image can be observed on the TV monitor 24.

When observing the image while still, the operator presses the image stilling switch 10 to issue a stilling instruction. When the image stilling switch 10 is pressed, an image stilling instruction signal is sent to the image stilling control circuit 11.

The image stillness control circuit 11 includes an image memory input switch (r
, g, b) 18.19.20 is switched in advance for each preset camera frame or field, and the remaining R, G, and B component image data are transferred at different timings.
In this embodiment, 4) image memories (R2 to R5) 22
~25. Image memory (G2-G5) 27-3o.

The images are sequentially recorded in the image memories (B2-B5) 32-35.

When recording to all the image memories is completed, the image selection control circuit 44 transfers the image data at each timing to the image memories (R1-R5) 21 to 251 and the image memories (01 to G
5) 26-303 image memory (Bl-B5) 31-35
The images are sequentially selected and read out, and sent to the color shift comparing means 43.

The color shift comparison means 43 detects at which timing the R, G, and B image recorded among the five image groups has the least color shift, and outputs the detection result to the image selection control circuit 44. . The image selection control circuit 44 controls the image memory output switches (r, g, b) 36, 38, 40 so that the image with the least color shift is displayed based on the detection signal from the color shift comparing means 43. Control switching. As a result, a still image with the least color shift is observed on the color monitor 42-.

At this time, the observed still image is the one with the least color shift among the five images, and is an easy-to-see image. To cancel image freezing, the image freezing control circuit 11 may be reset using a release switch (not shown) or the like.

The subject of an endoscope is mainly a living body, and as mentioned earlier, the subject often moves due to the subject's heart, heartbeat, and breathing, but both heartbeat and breathing have a cycle, and at a certain timing the subject moves. becomes stationary or has very little movement. Therefore, as in the above embodiment, by comparing the amounts of color misregistration using the color misregistration comparison means and selecting and displaying the image with the least amount of color misregistration, a still image from which the effects of color misregistration have been practically removed can be obtained. Obtainable.

FIG. 2 is a block diagram showing a specific example of the configuration of the color shift comparing means 43 in the embodiment shown in FIG. 1 above.

When the relationship between the green (G) component and the blue (B) component of a normal endoscopic image is investigated, it is as shown in FIG. From this figure, it can be seen that the G component and B component of each pixel constituting the endoscopic image vary within a limited range around a straight line function. The variation varies depending on the subject, but many pixels exist near the center straight line. Therefore, it can be considered that the ratio of the G component to the B component of many pixels in a normal endoscopic image is approximately constant.

Also, depending on the subject, the G and B components may be distributed in a polygonal line, as shown in Figure 4. It can be said that the ratio between the component and the B component is almost constant.

The configuration example shown in FIG. 2 is designed to detect color shift from green and blue image signals based on the above fact. That is, the output of the D/A converter (G) 39 is inputted to one input terminal of the subtracter 45 and also inputted to the integrator (1) 46. (B)4
The output of 1 is input to the other input terminal of the subtracter 45 via the variable gain amplifier 47, and is also input to the integrator (2) 48. and integrator (1) 46
and each output of the integrator (2) 48 is connected to a variable gain amplifier 47
The output terminal of the gain control circuit 49 is connected to the gain control input terminal of the variable gain amplifier 47.

The output terminal of the subtracter 45 is connected to a window comparator 50. The output terminal of the window comparator 50 is connected to an integrator (3) 51, and the output of the integrator (3) 51 is input to an A/D converter 52.
The output of 2 is sent to a register 53 consisting of a semiconductor memory or the like.
At the same time as the signal is input to the comparator 54, it is manually input to the comparator 54. The register 53 and the comparator 54 are connected to a timing control circuit 55 that controls various timings including the register 53 and the comparator 54, and the timing control circuit 55 outputs the minimum color shift image number. It looks like this.

Next, the operation of the color shift comparing means 43 configured as described above will be explained. First, the zero image data for one field or one frame is integrated by the integrator (1) 46 via the D/A converter (G) 39. On the other hand, D/A converter (B) 4
1 and a variable gain amplifier 47, an integrator (2) 4B integrates three image data for one field or one frame. The outputs of the integrator (1) 46 and the integrator (2) 48 are compared in a gain control circuit 49.
The gain of the variable gain amplifier 47 is controlled so that the outputs of the side divider (1) 46 and the integrator (2) 4B are equal.

As a result, in a normal endoscopic image, although the G component has a higher level than the B component, the G component and B component of the image signal input to the subtracter 45 are within the field or frame period. The integral values become equal. The subtracter 45 is D/
A pixel that outputs the difference between the output of the A converter (G) 39 and the output of the variable gain amplifier 47, but makes the output of the subtracter 45 almost 0 when no color shift occurs, that is, the G component;
There are many pixels in which the value obtained by multiplying the B component by the gain of the variable gain amplifier 47 is equal. On the other hand, when a color shift occurs, the number of pixels that cause the output of the subtracter 45 to be O is smaller than the above.

The window comparator 50 extracts only the pixel signals for which the output of the subtracter 45 is near O, and each time the integrator (3) 51 integrates the pixel signals for the entire screen, the amount of color shift for the entire screen is obtained. Therefore, the output of the integrator (3) 51 indicates the amount of color shift. In order to detect the image with the minimum output of the integrator (3) 51 indicating the amount of color shift, the output of the integrator (3) 51 is digitized by the A/D converter 52, and the previous comparison result is stored. The data is inputted to a comparator 54 for comparison with the contents of the register 53, which is currently being stored. Note that when comparing the first image, register 5
All you have to do is reset 3 and clear it to 0. The amount of color shift of the five images is compared sequentially, and finally the register 53 stores an integrator (
3) The value of 5] is digitized and recorded. Then, the timing control wholesale circuit 55 outputs the image memory number corresponding to the image with the smallest amount of color shift based on the contents of the register 53.

In the above embodiment, a configuration is shown in which a plurality of images are sequentially recorded in the image memory group after the image freeze switch 10 is pressed, but the present invention is not limited to this, and the image memory group Record multiple images sequentially or cyclically, and press the image freeze switch 1.
The configuration may be such that the image with the smallest amount of color shift is selected from a plurality of images immediately before the 0 operation. Since it takes some time for the operator to perform an image freeze operation, the freeze timing is delayed. The above method is useful because it can eliminate this delay.

Further, in the color shift comparison means shown in FIG. 2, the integrator (1) 46. Integrator (2)48. Although the integral is integrated over the entire screen using the integrator (3) 51, etc., in a normal electronic endoscope, the endoscope image area is only a part. Therefore, when performing various types of integration using each integrator described in Section 2,
It is necessary to exclude pixels other than those in the endoscopic image area. To this end, it is sufficient to generate a mask signal indicating the endoscopic image area and to control the function of the integrator accordingly.

Furthermore, color shift detection may not be performed on the entire endoscopic image, but may be performed only on the central part of the image or only on a specific scanning line, for example. In this case, it is sufficient to generate an appropriate mask signal and perform color shift detection only in a specific area.

Furthermore, in the color blur comparison means shown in FIG.
) component and the blue (B) component to detect color misregistration, the present invention is not limited to this, and may be configured to detect color misregistration using images of other color components. Furthermore, the configuration may be such that color shift is detected by using a two-color color component image whose contours have been enhanced or extracted after performing differential processing on the image or the like.

Furthermore, although video signals obtained from electronic endoscope devices are generally gamma-corrected, in the present invention, the video signals are linearized through a circuit with inverse gamma characteristics before being processed. It may be configured as follows.

Further, the color misregistration prevention device according to the present invention may be incorporated into an electronic endoscope device, or may be configured separately from the electronic endoscope device, and may be configured using a video signal obtained from the electronic endoscope device. The image freezing operation of the electronic endoscope device may be controlled from the outside by detecting color shift.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, the color shift amount detecting means detects an image with the least color shift and displays the image, so that a still image with little color shift is displayed. images can be easily obtained. Therefore, it is no longer necessary to perform complicated operations to repeatedly instruct the patient to stand still and release the patient from rest, thereby providing advantages such as shortening the examination time and reducing the patient's pain. Furthermore, compared to a method that corrects color misregistration, it is possible to provide a color misregistration prevention device that has a simple configuration and is small and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a color misregistration prevention device in an endoscope imaging device according to the present invention, and FIG.
FIGS. 3 and 4 are block diagrams showing an example of the configuration of the color shift comparison means in the figure, and are diagrams showing the distribution state of the green component and the blue component of each pixel constituting an endoscopic image. In the figure, ■ indicates an electronic endoscope, 3 indicates an image sensor, and 4 indicates a light guide.

Claims (1)

[Claims] 1. In an endoscopic imaging device using a color sequential illumination method,
An image stilling instruction means, a means for recording a plurality of frames or field images, and an image stilling instruction from the image stilling instruction means to determine the amount of color shift that is the largest among the plurality of frames or field images recorded in the recording means. 1. A color shift prevention device comprising: means for detecting an image with the least amount of color shift, and configured to select and display an image with the smallest amount of color shift based on a detection signal of the detection means.