JPH1132238A - Image-receiving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image free of flickers by comparing two images or over photographed at different times, detecting parts different by a prescribed value between the images as a flickered part and composing the parts of the respective images with the flickered parts removed from them as effective parts. SOLUTION: Two images are received at a time deviation, an absolute value of a difference is calculated for each pixel as to the two images, and pixels with the absolute value over a prescribed value are used for ineffective parts and marked to generate an intermediate image. The parts not discriminated as the ineffective parts are left as the effective parts. Whether or not the intermediate part has ineffective parts is discriminated, and when no ineffective part exists in the intermediate part, the intermediate part is outputted as a final acquired image. When the ineffective part is exists in the intermediate part, one image is received again, ineffective part is detected and the effective parts are embedded in the ineffective part of the intermediate image to obtain a new intermediate image. The operation is repeated until the ineffective part is not found out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (CR)
T), imaging of an image displayed on a display device using a liquid crystal display, a plasma display, an electroluminescence display, or the like by a TV camera (color / monochrome) or another two-dimensional image pickup device.

[0002]

2. Description of the Related Art When an image of a display device is picked up by a TV camera, a vertical synchronization frequency of the two does not match.
Asynchronous noise occurs. This is called flicker or flicker noise. Flicker noise is observed as a horizontal bright or dark stripe pattern on the display screen, and an image different from the originally displayed pattern is taken. Will be.

[0003] In the patent of Japanese Patent Publication No. 7-82813,
It describes that image capture is performed by detecting and removing flicker noise. In this patent, as a method of detecting the flicker noise, it is assumed that the light emission distribution of the light emitting surface of the CRT in one image is substantially constant, and the light emitting portion is binarized by one threshold value. A portion where the level is equal to or higher than the threshold is detected and removed as a flicker portion.

[0004]

The above patent assumes that the light emitting surface has a uniform light emission intensity distribution. However, the emission intensity distribution on the CRT display surface cannot be regarded as constant due to luminance grading. Also, it is good if a pattern with no pattern is displayed like a monochromatic raster screen, but if any pattern is displayed, it does not have a constant light emission intensity distribution, so flickering at a certain threshold Cannot be detected by threshold processing.

[0005]

According to the present invention, two or more pieces of image data captured at different times are compared, and a portion having a value that differs by a certain value or more between the images is detected as a flicker portion. Thereafter, by combining only the portion excluding the flicker portion in each image as an effective portion, an image from which flicker has been removed can be obtained.

Alternatively, flicker is removed by comparing three or more pieces of image data captured at different times and taking a median value for each pixel between those images.

When an interlaced TV camera is used, its characteristics can be used. That is, since the images included in the interlaced ODD output and the EVEN output are captured at different timings, the TV camera outputs, ODD and EVE, are output.
If the synthesized image of N is examined, flicker is included in one of ODD and EVEN in a certain portion of flicker, and is not included in the remaining one, so that an output whose value differs by a certain value or more every 1H line may be obtained. High in nature. For this state, for example, a difference filter of two adjacent pixels in the V direction is applied to calculate the absolute value, and a portion where the value is higher than a certain value can be determined to be flicker. In this case, it is assumed that the pattern to be imaged does not include a high-frequency component that changes every 1H line. Also, basically, in the present invention, it is assumed that images captured at a plurality of different timings hardly change over time due to causes other than flicker, so that the present invention is suitable for capturing a display on which a moving image is displayed. No

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. FIG. 2 shows the configuration of the image capturing device according to the present invention. In FIG. 1, reference numeral 1 denotes a two-dimensional image capturing device such as a TV camera, and reference numeral 2 denotes an image input device that receives an output from the one image capturing device. The image input device 2 includes an A / D converter 3 and an image memory 4. Reference numeral 5 denotes an image processing device that executes the image capturing method according to the present invention. In this image capturing method, with such a device configuration, an image from which flicker has been removed is obtained from a plurality of images captured at different timings in time.

A processing method for obtaining an image from which flicker has been removed in the image processing apparatus 5 of FIG. 2 will be described with reference to the flowchart shown in FIG. First, in step 102, two images are captured at different times. Then 104
Calculates the absolute value of the difference between the two images for each pixel, and creates an intermediate image in which a pixel portion whose value is equal to or greater than a predetermined value is marked as an “invalid portion”. . The part that is not determined as an invalid part is a valid image and is left as an “effective part” in the intermediate image. Thereafter, steps 106, 108, 110, and 112 are repeated until the effective screen fills the entire image.

At 106, it is determined whether or not there is an invalid portion in the intermediate image. If there is no invalid portion, the image is output as a final acquired image. If there is an invalid portion, the process proceeds to 108.
At 108, one image is captured again. Next, at 110, this image is compared with the previous image in the same manner as at 104, and the invalid portion of the new image is determined. If the effective portion of the new image overlaps the invalid portion of the intermediate image, which has been determined in step 106 as to whether or not there is an invalid portion, the effective portion is embedded in the intermediate image to be a new intermediate image. Thereafter, by repeating steps 106 to 112, when the invalid portion finally disappears from the intermediate image, at 114, the intermediate image without this invalid portion is output as the final captured image, and the process ends.

FIG. 3 illustrates the above procedure using an example.
It is. In FIG. 3, a shaded portion is an invalid portion. First, in step 102, two images 301 and 302 are captured. The image 301 has flicker at the top, and 302 has flicker at the center.
Next, in step 104, the flicker portion included in both 301 and 302 is recognized as an invalid area, and an intermediate image (A) of 303 is created. Next, in step 106, since the intermediate image (A) contains an invalid portion, the process proceeds to step 108. Then, the third image 304 is captured, and the procedure 11
At 0, the image 304 and the image 302 are compared, and an image 305 in which the flicker portions of both are determined to be invalid is created.

Then, in step 112, 3 of the portions invalid in the intermediate image (A) 303 and valid in the image 305
By embedding the image portion on the image 05 in the intermediate image (A) 303, the intermediate image (B) 306 is synthesized.
Here, returning to step 106, it is determined that there is still an invalid portion.
Import 7 Image 307 and image 304 in step 110
Are compared, an image 308 is created as before, and
In, a portion that is invalid on the image 306 and valid on the image 308 is embedded in the image 306 to create an intermediate image 309. Here, when the procedure returns to step 106, it is determined that there is no invalid portion, and the procedure proceeds to step 114, where the image 309 is output as the final captured image, and the entire process is completed.

In this example, four images are captured to obtain an image from which flicker has been removed. However, depending on the vertical synchronizing frequency on the display side and the imaging timing on the camera side, flickering is performed after capturing a larger number of images. Will be removed.

Next, another embodiment will be described with reference to FIGS. 4 and 5. FIG. The configuration of the image capturing device is the same as that of FIG. 2, but the TV camera is limited to an interlaced type. First, in step 402 of FIG. 4, the first image is fetched, subjected to a difference filter, and an image having the absolute value of the output is created. The difference filter used here is g (i, j) = f (i, j + 1) −f (i, j) when the input image is f (i, j) and the output image is g (i, j). ).
Where i is the abscissa of the image and j is the ordinate. At this time,
A waveform 502 in FIG. 5 schematically shows an arbitrary vertical luminance distribution of the input image. A jagged waveform appears between the two dotted lines. This is a diagram in which flicker is applied to only one of ODD and EVEN, and the value greatly fluctuates every other pixel in the vertical direction. I have.

Therefore, when the absolute value is obtained by applying the above-described difference filter, the output increases only in a portion where flicker is applied as shown in a waveform 504. Therefore, the part is marked as an invalid part and an intermediate image is formed as shown in FIG.
This is the procedure 404. Next, the procedure proceeds to step 406, and since there is an invalid portion in the intermediate image, the procedure proceeds to the following steps 408 and 410. Here, the same processing as the previous steps 402 and 404 is repeated again. If the vertical distribution of the captured image at this time is as shown by a waveform 506 in FIG. 5, the output obtained by applying the difference filter and taking the absolute value is as shown by a waveform 508. Step 40 to the invalid part of
By embedding a non-invalid part of the image taken in 8, a final image having no invalid part is obtained as shown by a waveform 510 in FIG. Note that, depending on the vertical synchronization frequency on the display side, the imaging timing on the camera side, and the like, flicker is removed after a larger number of images are captured.

Another embodiment will be described below. N (N is 3 or more) images are captured. Let the coordinates of each pixel be (i,
j). The captured N images are _represented by f _k (i, j) (k = 1,
2, ..., N). n number sequences {f _k }
The process of taking the median of (k = 1, 2,..., N) is med
_When it is decided to express _k {f _k }, the next image g (i, j) is calculated and output.

[0017]

(Equation 1)

As a result, if N is appropriately increased, almost no flicker portion having an abnormal value is obtained.

[0019]

According to the above-described image capturing method, even if the target image contains shading or a picture,
By determining and removing a flicker portion by using a plurality of images captured at different times, an image without flicker can be synthesized and output.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a processing procedure according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of an image capturing device according to the present invention.

FIG. 3 is a diagram exemplifying a state in which an invalid flicker portion is removed by the processing procedure shown in FIG. 1 of the present invention.

FIG. 4 is a flowchart illustrating a processing procedure according to another embodiment of the present invention.

FIG. 5 is a view exemplifying a state in which an invalid flicker portion is removed by the processing procedure shown in FIG. 4 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Two-dimensional image imaging device, 2 ... Image input device, 3 ... A /
D converter, 4 ... Image memory, 5 ... Image processing device.

Claims (3)

[Claims] 1. A two-dimensional imaging device such as a TV camera,
When capturing a display such as a CRT, two or more images are captured, an abnormal value portion in each image is detected by comparing them, and an image obtained by removing the abnormal value portion from each image is combined. An image capturing method characterized by obtaining an image without an abnormal value portion. 2. An interlaced TV camera provides a CR
When capturing a display such as T, a single image is captured, a difference filter that outputs the difference between two pixels arranged in the vertical direction is applied to the entire image, and the absolute value is obtained for each pixel. If there is no such part (pixel), the captured image at this time is output as the final captured image. If there is a part with a certain value or more, it is deleted as an abnormal pixel part, and the next one image is newly captured. Similarly, the abnormal value portion is deleted, these two images are superimposed, and if there is no abnormal value portion, it is output as the final captured image. If the abnormal value portion still remains, the following 1 Repeat the series of operations of capturing images, deleting outliers, and superimposing images until there are no outliers.
An image capturing method characterized by outputting the result as a final captured image. 3. A two-dimensional imaging device such as a TV camera,
When capturing an image on a display such as a CRT, three or more images are captured, and one image is configured by taking the median of the luminance values of the plurality of images for each pixel of the imaging device. Image capture method.