JPH06319694A - Color drift correcting device - Google Patents

Abstract

PURPOSE:To provide a color drift correcting device capable of correcting even a portion having large motion with the color near the color of an original object, resolving a color drift, and obtaining an image having no sense of incompatibility. CONSTITUTION:A color drift correcting device is constituted of a color change detection section 1 comparing image signals having a time difference from the color image signals obtained by an image pickup means photographing an object in sequence and detecting the change point of an image corresponding to a color drift, a corrected image forming section 2 generating the histogram of the color distribution from the color image signals, computing the representative color from the provided color distribution, calculating the color drift correction data for correcting the color drift, and producing the corrected image corrected with the color drift of an image, and a synthesis section 3 switching the original image to the corrected image and outputting it when the color drift is detected on the original image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates data for color misregistration correction based on the color distribution created by a color distribution creating means,
The present invention relates to a color shift correction device that performs color shift correction.

[0002]

2. Description of the Related Art A frame sequential electronic endoscope captures R, G, B three primary color images one by one every 1/60 seconds. Therefore, when a moving object is imaged, R,
Since the three primary colors G and B cannot be captured, the colors of the object are separated. This separated state is called color shift.

The method of correcting the color shift according to Japanese Patent Publication No. 52-9095 compares the original signal and the three-field delay signal, that is, each primary color signal of the original signal and the original color signal of the same color three fields before and comparing the difference. When the signal exceeds a certain value, it is determined that the position is the motion position of the image causing color breakup, and the carrier signal is gain-controlled and band-controlled by this motion position determination signal (pulse) to determine the carrier color signal. Completely remove it at the moving position of the image or suppress it to reduce color breakup of the three primary colors.

Further, there is disclosed a field sequential color television image pickup system for reducing color breakup, in which two or more switching systems for switching to a bandpass filter having a narrower band may be used when the motion is large.

[0005]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 52-9095
In this case, since the band of the color signal is limited according to the color shift, the color becomes weaker in a portion having a large movement and becomes closer to a monochrome image, resulting in an unnatural image different from the original subject color.

The present invention has been made in view of the above points, and a color misregistration correction device capable of eliminating a color misregistration that is complementary to a color close to the original subject color even in a portion having a large motion and obtaining an image without a feeling of strangeness. The purpose is to provide.

[0007]

A change point or a change area of an image corresponding to a color misregistration is calculated by comparing image signals with a time difference from color image signals obtained by an image pickup means for picking up a subject in a frame sequential manner. Change portion calculating means, color distribution creating means for creating a color distribution from a color image signal of a subject, and color misregistration correction for calculating color misregistration correction data for color misregistration correction from the color distribution created by the color distribution creating means. A data calculation unit and a corrected image generation unit that corrects the color misregistration of the image using the color misregistration correction data are provided.

[0008]

Since the endoscopic image is an image inside the body cavity unlike the normal image, the colors forming the image are considerably deviated, so that the pixel density of a part of the color space becomes high. If a representative color having a high pixel density is searched for in the color space, the color shift image can be corrected with a color close to that in the body cavity.

That is, a representative color is generated from the color distribution created by the color distribution creating means, color shift correction data is calculated using this representative color, and correction is performed using this calculated color shift correction positive data. By doing so, a natural corrected image with no discomfort can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 relate to an embodiment of the present invention.
2 shows the basic configuration of the color misregistration correction device according to the first embodiment, FIG. 2 shows the configuration of the color change detection part, FIG. 3 shows the structure of the corrected image creation part, and FIG. 4 is the color misregistration correction device of the first embodiment. 5 shows the flow of histogram creation, FIG. 6 shows an explanatory diagram for obtaining the representative color of the maximum value of the number of pixels frequency from the color space histogram, and FIG. 7 and FIG. Reference numeral 8 shows an explanatory diagram for obtaining a lookup table of a representative color.

As shown in FIG. 1, a color shift correcting apparatus 10 of the first embodiment has a color change detecting section 1 for detecting a color change pixel such as a color shift from an input original image signal, and a color shift detecting section. It is composed of a corrected image creation unit 2 that creates a corrected image of a color change portion and a combining unit 3 that combines the original image and the corrected image based on the color change detection unit 1.

As shown in FIG. 2, the color change detection unit 1 receives a luminance signal Y from two R, G and B signals and two color signals C.
A matrix circuit 11 for calculating r and Cb, four field delay memories 12a and 12b for delaying the calculated color signals Cr and Cb signals by four fields, respectively, and four field delayed color signals Cr and Cb and the matrix circuit 11
Difference detection circuits 13a and 13b for detecting the difference between the color signals Cr and Cb calculated in
It is composed of a logical sum circuit 14 for calculating the logical sum of the detection results of b.

The change point detection signal output from the logical sum circuit 14 is input to the corrected image creating unit 2 for use in selecting pixels without color shift, and is also input to the synthesizing unit 3 for inputting the original image and the corrected image. Used for switching.

As shown in FIG. 3, the corrected image creating section 2 uses the result of the color change detecting section 1 as an original image (input R,
G and B signals), a histogram creation circuit 21 that creates a histogram for one field, a CPU block 22 that creates a representative color from the histogram data of this histogram creation circuit 21, and a color that creates a correction color from the original image. It is composed of a conversion unit 23 and a calculation unit 24 that matrix-calculates the luminance signal Y of the original image and the correction color of the color conversion unit 23 to create a correction image. The calculation unit 24 outputs the correction image.

The histogram creating circuit 21 selects the R, G, B signals input and the signal read from the last image field memory 212.
1 and the field memory 212 for the last image that stores the signal selected by the selector 211 for one field
And a histogram LSI 213 that creates a color distribution from signals for one field stored in the last image field memory 212.

The CPU block 22 is a histogram LSI
A representative color is selected from the histogram data created in step 213 to create a lookup table.

The color conversion means 23 inputs R, G, B
Field memory 2 that delays the signal by one field time
31a, 231b, 231c, and a look-up table 23 for recording the representative colors selected by the CPU block 22.
2a to 232f, multipliers 233a to 233f that weight the converted colors, and adders 234a and 23 that add the color signals weighted by the multipliers 233a to 233f.
4b and.

Further, the calculation section 24 includes a matrix circuit 11
A field memory 241 for delaying the luminance signal Y created in step 1 by one field time, and adders 234a and 234b.
A matrix circuit 24 for creating an image from the color signal created in step S1 and the luminance signal Y delayed in the field memory 241.
The color signals R ', G', and B'of the corrected image output from the calculation unit 24 are input to the synthesis unit 3.

The synthesizing unit 3 switches the original image and the corrected image calculated by the matrix circuit 242 on the basis of the color shift detection result of the color change detecting unit 1, and the color shift occurs even if the color shift exists. Output few images. This synthesizer 3
Is composed of, for example, an analog switch.

FIG. 4 shows an electronic endoscope apparatus 71 equipped with the color misregistration correction apparatus 10 of the first embodiment.

This electronic endoscope device 71 is an electronic endoscope 72.
And a light source unit 73 that supplies illumination light to the electronic endoscope 72.
And a video processor 75 including a signal processing unit 74 that performs signal processing for the image pickup means of the electronic endoscope 72,
The color monitor 76 displays the video signal output from the video processor 75.

The electronic endoscope 72 has an elongated and flexible insertion portion 77, for example, and a large-diameter operation portion 78 is connected to the rear end of the insertion portion 77. A flexible universal cable 79 extends laterally from the vicinity of the rear end of the operation portion 78, and a connector 80 is provided at the tip end of the cable 79.

The connector 80 is connected to the video processor 75.
By connecting to the electronic endoscope 72 from the light source unit 73
The frame-sequential illumination light is supplied to the light guide 81. That is, the white illumination light of the lamp 82 is passed through the R, G, and B color transmission filters 84R, 84G, and 84B provided in the rotary filter 84 that is rotationally driven by the motor 83, so that the R, G, and B frame sequential illumination is performed. It becomes light and the light guide 8
The light is emitted forward from the tip surface of 1.

A subject such as a diseased part illuminated by the field-sequential illumination light is imaged by the objective lens 85 at the tip end on the CCD 86 arranged on the focal plane thereof and photoelectrically converted. This CCD8
The image signal photoelectrically converted by applying a drive signal from the driver 87 to 6 is read out, amplified by the amplifier 88, converted into a digital signal by the A / D converter 89, and further converted by the selector 91 into the R signal. , G, B memories 92R, 92G, 92B are sequentially stored.

The R, G, B memories 92R, 92G, 9
The image data sequentially stored in 2B are read out at the same time,
After being input to the color misregistration correction apparatus 10 of the first embodiment and subjected to color misregistration correction, it is converted into an analog color signal by the D / A converter unit 94, and is input to the color monitor 76 together with a synchronization signal (not shown), and the subject image Is displayed in color.

Next, the operation of the color misregistration correction device 10 of the first embodiment will be described. Since the color change detection unit 1 compares the color signals having the time difference of four fields, the digital R, G, B signals are converted into color signals Cr, Cb by the matrix circuit 11. The color signals normally use R-Y and B-Y, but when the calculation is performed with 8 bits for each of R, G, and B, it becomes 9 bits.
The color signal that can be stored in the 8-bit width is Cr,
It is indicated by Cb.

The two color signals Cr and Cb are input to the 4-field delay memories 12a and 12b and delayed by 4 field time. In the difference detection circuits 13a and 13b, the color signals Cr output from the matrix circuit 11 without being delayed,
Cb and the color signals Cr and Cb delayed by the four-field delay memories 12a and 12b are respectively subtracted, and if the result is positive, positive side comparison is performed, and if negative, negative side comparison is performed.

A color change is detected by comparing each with a predetermined value. Note the color signal Cr, so either because they are composed of two kinds of Cb is that there was a color change if put out the determination of the discrepancies two difference detection circuit 13a, 13
The output of b is synthesized by the logical sum circuit 14 to detect a pixel having a color change, and the logical sum circuit 14 outputs a change point detection signal when a pixel having a color change is detected. This change point detection signal is output to (the histogram creating circuit 21 of) the corrected image creating unit 2 and the synthesizing unit 3.

The histogram creating circuit 21 first uses the selector 211 to create a histogram of the color space from the pixel data of the image for one field without color shift, and the first image is stored by the selector 211. The image of the field memory 212 for selection is selected by the change point detection signal, and the selected pixels having no color change are stored in the field memory 212 for last image.

The histogram LSI 213 creates a color space histogram by using the upper 3 bits of each 8 bits of R, G, B of the image data for one field stored in the last image field memory 212. In addition,
The field memory 213, which stores pixel data of an image for one field without color misalignment, has no content if read out because it has, for example, a FIFO structure. Therefore, it is fed back to the selector 211 and a pixel without color misregistration immediately before the color misalignment occurs. Memorize

In the CPU block 22, R, G, B = 8
Work to select a representative color from a × 8 × 8 color space. Normal,
When a representative color is selected, the color space is often connected by one line, but this representative color calculation method passes three lines through the color space in order to select two colors from one color.

The reason therefor is that one of R, G, and B is missing in the color where the color shift occurs, and in the worst case, an image may be formed with one color. This is because there is no choice but to estimate the two colors. Unlike the normal image, the endoscopic image is an image inside the body cavity, and the colors forming the image are considerably deviated, so that it is possible to estimate one or two colors.

This representative color calculation method will be described with reference to the flowchart of FIG. First, the color space histogram is read out as shown in step S1, then the maximum value (color with the maximum frequency) is selected from each color plane as shown in step S2, and for the maximum values R, G, B, step S3 is performed. The color signals Cr and Cb are calculated as shown in.

Then, as shown in step S4, the color signal C
After interpolating the values of r and Cb into 8-bit gradation, step S
5, lookup tables 232a-232
Write to f. Look-up tables 232a-232
For f, the color signals Cr and Cb are estimated for each pair from one reference color.

Look-up tables 232a to 232f for estimating the color signals Cr and Cb from one reference color.
Will be further described with reference to FIGS. When estimating two colors from the reference one color from the color space, for example, when R is used as the reference, G and B are selected from the color space and R (original image color), G '(estimated color), B' ( 1) of estimated color
Become a pair.

The method is R, G, B as shown in FIG.
Histogram value (pixel count frequency value) at the color space coordinate position of
The color space coordinates of R (gradation of R) in the color space histogram corresponding to are divided into eight, for example, from 10H to F0H, and eight GB planes are prepared as shown in FIG. 6B.
The densest part in each plane is selected, and the G and B coordinate values of that part are recorded as the estimated color.

For example, if the highest density portion (maximum pixel number frequency value) is the thick frame portion shown in FIG. 6B on the G-B plane when R = F0H, the coordinates of G and B are shown. Since the positions are D0H and B0H, respectively, this is the estimated color.

The other 7 G-B planes are also searched to obtain data of 8 points for estimating G from R and data of 8 points for estimating B from R. This is also searched for on the RB plane and the RG plane, and a table as shown in FIG. 7 is created.

However, what is obtained here is the R, G, B data for both input and output, and not the color data that is finally needed. Therefore, a matrix operation is performed to obtain R, Cr, C.
8 points of b, 8 points of G to Cr and Cb, and 8 points of B to Cr and Cb are obtained and the table of FIG. 8 is created. Next, interpolation processing is performed from the data of 8 points to 256 points, and the result is looked up in the lookup table 232.
a to 232f.

In the color conversion section 23, the look-up table 2 into which the representative colors selected by the CPU block 22 are written
3 sets of color data from 32a to 232f are multiplied by a multiplier 233a.
.About.233f and weighted and added for each color data to obtain color signals Cr and Cb.

Next, the calculation section 24 uses the correction circuit color signals Cr and Cb created by the color conversion section 23 and the luminance signal Y of the original image created by the matrix circuit 11 as a matrix circuit 242.
Then, matrix calculation is performed in order to obtain corrected images of R ', G', B '. The luminance signal Y is delayed by the field memory 241 and input to the matrix circuit 242 because one field time is required to create the color distribution.

The corrected image thus obtained and the original image are switched on the basis of the color change points, and the combined image is output, whereby the color shift can be corrected without weakening the color. When a color shift is detected in this way, the correction image is used for correction, so that a natural correction image with no discomfort can be corrected.

By setting the data for halation correction in the color space histogram for color shift correction in advance,
It is possible to satisfactorily correct the color shift based on halation.

Further, an image in which no color shift has occurred and an original image may be combined according to the amount of color shift. Further, the RY and BY signals having a time difference are compared, and if only one of the image signals is changed, only the changed color signal may be replaced with image data in which no color misregistration occurs. good.

Further, instead of linearly interpolating the data of 8 points for each color calculated from the color space, a one-dimensional LPF is used.
Alternatively, smoothing processing may be performed to obtain multiple gradations. Further, when interpolating the data of 8 points for each color calculated from the color space, 256-gradation data may be obtained by interpolating with a straight line passing through the middle between adjacent points. By interpolating between the data to be corrected, the flat part of the estimated data can be reduced and natural correction data can be obtained.

Further, since each correction data is estimated only in the upper bit and the lower bit outputs the original image as it is, even if the estimated data of 8 points is used as it is, since the correction color changes smoothly, a natural correction is performed. It becomes data. The number of divisions of the color space and the color plane is not limited to 8 * 8 * 8 and 16 * 16, and other division numbers may be used. Further, the color space and the color plane are other uniform color planes (such as the uv color plane) and the uniform color space (L *, a
*, B * or Y, RY, BY color spaces, etc.) may be used.

[0047]

As described above, according to the present invention, since the color distribution state is grasped and the correction color is selected, color correction is performed with a color close to the original subject color regardless of whether the movement is large or small. Therefore, even if color misregistration occurs, it is possible to perform highly accurate color misregistration correction without causing a feeling of strangeness.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a color misregistration correction device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a color change detection unit.

FIG. 3 is a block diagram showing a configuration of a corrected image creating unit.

FIG. 4 is a configuration diagram showing a configuration of an electronic endoscope apparatus including the color misregistration correction apparatus according to the first embodiment.

FIG. 5 is a flowchart of histogram creation.

FIG. 6 is an explanatory diagram for obtaining a representative color having a maximum value of pixel frequency from a color space histogram.

FIG. 7 is an explanatory diagram showing representative colors of R, G, and B.

FIG. 8: Color signals Cr, C corresponding to representative colors of R, G, B
Explanatory drawing which shows b.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Color change detection part 2 ... Corrected image creation part 3 ... Compositing part 10 ... Color shift correction device 11 ... Matrix circuit 12a, 12b ... 4 field delay memory 13a, 13b ... Difference detection circuit 14 ... Adder 21 ... Histogram creation part 22 ... CPU block 23 ... Color conversion unit 24 ... Arithmetic unit

Claims (1)

[Claims] 1. A changing portion calculating means for calculating a changing point or a changing area of an image corresponding to a color shift by comparing image signals having a time difference from a color image signal obtained by an image pickup means for picking up a subject in a frame sequential manner. A color distribution creating means for creating a color distribution from the color image signal of the subject; and a color misalignment correction data calculating means for calculating color misalignment correction data for color misregistration correction from the color distribution created by the color distribution creating means. And a corrected image generating unit that corrects the color shift of the image using the color shift correction data.