JPH01150986A - Picture quality inspection device - Google Patents

Abstract

PURPOSE:To improve detecting performance and to obtain a simple and high- speed processing by making feature quantity remarkable and compressing data by projection by obtaining a marginal distribution partially and executing a differential processing for the compressed data. CONSTITUTION:A video signal S1 by a reference white light image-picked up with an image pickup device 2, which is an inspection object, is quantized at a decoder 3 and stored in a picture memory 4. Next, a marginal distribution f(Px, y) of respective partial areas, which are indicated with oblique lines in a figure (a), is obtained in order to obtain a partial marginal distribution project ed in an X-axis direction. The f(Px, y) is smoothed in order to eliminate noises, and the sum of products Sy of the differential value of the f(Px, y) is obtained. For the partial marginal distribution projected in a Y-axis direction, the same processing is executed, and Sx is obtained by replacing the values of (x) and (y) of the respective processings and repeating the processings. Thereafter, the Sx and the Sy are compared with a previously set threshold, the existence and absence of the unevenness of density is discriminated, and the decided result is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image quality inspection device that inspects the presence or absence of density unevenness such as spots in a video signal of an imaging device or the like.

(Prior Art) For example, as a CCD color image sensor, one is known in which three primary color filters of red, blue, and green are attached to each CCD image sensor, and an image is divided into three primary colors and read. However, if the attachment of the filter is uneven or incomplete,
Color unevenness (density unevenness) occurs in the obtained video signal, making it impossible to obtain a high-quality image.

As mentioned above, typical conventional methods for detecting density unevenness that fundamentally exists in a video signal include density histograms, marginal distribution, and differential processing. However, in peripheral distribution, etc., where the entire image is processed uniformly, the density changes are averaged out, making it impossible to detect them well. For example, regarding density unevenness that extends over the entire screen in a diagonal band shape as shown in Figure 4(a), the peripheral distribution projected in the X-axis direction is found to be flat as shown in Figure 4(b). , and the change is not noticeable.

On the other hand, with the differential method that extracts local density changes, if there is a clear difference between the density unevenness and the background, the boundary can be detected using a small differential filter of about 3x3.
As shown in Figure (C), when the density changes slowly and the boundary between the density unevenness and the background is unclear, processing must be performed using a large differential filter, which requires a huge amount of calculation. Ru.

(Problems to be Solved by the Invention) As described above, the conventional method has a problem in that a large amount of calculation is required to detect density unevenness.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide an image quality inspection device that can perform high-speed processing using a simple method.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides an apparatus for inspecting the presence or absence of density unevenness contained in a video signal of an object to be inspected, such as an imaging device. a storage means for quantizing a video signal from the inspection object, which is an image of a reference white light source, and storing it in XxY areas; and several parts preset in a band shape from the areas of this storage means. means for reading out a video signal of a region; means for determining a peripheral distribution of density in a preset projection direction for the video signal of each partial region obtained from the partial region extracting means; Detecting density unevenness from the video signal, comprising means for calculating the amount of change in density for each region, and means for comparing the value of the amount of change with a preset threshold value to determine the presence or absence of density unevenness. It is characterized by
・ (Function) This invention improves detection performance by partially taking marginal distributions, making feature values more prominent, compressing data by projection, and performing differential processing on the compressed data. We aim to simplify and speed up processing.

(Embodiment) FIG. 1 shows the configuration of an embodiment of the apparatus according to the present invention.

The image quality inspection device 10 of this embodiment captures the video signal S1 of the imaging device 2 that captures the irradiation light of the light box 1, and examines density unevenness such as spots contained in the video signal S1 in consideration of human visual characteristics. It is used for detection.

One light box, with a white light source as a reference light source,
White light is irradiated toward the imaging device 2 to be inspected.

The imaging device 2 is, for example, a CCD color image sensor, and is configured with a red, blue, or green color filter attached to each pixel. As mentioned above, due to non-uniformity or imperfection when attaching these color filters to each element, the video signal of the imaging device 2 fundamentally contains the image shown in FIG. 4(a). There is a possibility that band-like density unevenness may be included.

The image quality inspection device 10 includes a decoder 3 that samples and quantizes the video signal S1 from the imaging device 2, and a decoder 3 that samples and quantizes the video signal S1 from the imaging device 2, and converts the quantized video signal into an XxY-256x25
6, and a density unevenness memory 4 that can perform the process shown in FIG. It includes a detection control section 5 and a display section 6 formed of a CRT display that displays the video signal s1 as an image and displays the position of the detected density unevenness.

This embodiment has the above-mentioned structure, and its operation will be explained below with reference to FIG. 2 and subsequent drawings. , on the flowchart in Figure 2! The image is captured by the imaging device 2 to be inspected so that
The video signal S1 based on the reference white light thus obtained is quantized by the decoder 3 and stored in the image memory 4. The size of the image is i:XxY-256x256 (
pixels).

Next, in order to obtain the partial peripheral distribution projected in the X-axis direction, the peripheral distribution of each partial area indicated by diagonal lines in Fig. 3(a) is calculated by adding 8°y K±0 to (x −1~25B, y −33,97,181,
225) (D is the density of the pixel indicated by X+'l)l
Find y. f(P) is smoothed by x,y to remove noise and becomes f(P)−-Σ f(P)158°y
K, -2X" k -y (X-3~254.
5). and the sum of products S of the differential values of f(P).

-y (x = 33 ~ 224. y -33,97,1
81,225) (h is a certain threshold).

The above processing is an explanation of the partial marginal distribution projected in the X-axis direction, but by repeating the X+Y values of each process, Similar processing is performed on the partial marginal distribution projected onto , and S is obtained.

Then, the ratio y of S and S to a preset threshold value is The presence or absence of density unevenness is determined by comparing the images, and the judgment results are displayed.

[Effects of the Invention] As explained above, according to the present invention, it can also be used as a tooth quality testing device! This makes it possible to quickly produce test strips with density-based unevenness through simple processing.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a flowchart showing the processing procedure of an embodiment of the invention, Fig. 3 is a block diagram of the image memory, and Fig. 4 shows density unevenness. FIG. 2 is a diagram illustrating the characteristics of the system and an example of processing according to a conventional method. 1 ・・・・・・・・・Light box 2・・・・・・
...... Imaging device 3 ......
・Decoder 4 - Image memory 5 ・
......Density unevenness detection control section 6...
...Display section

Claims (3)

[Claims] (1) A device that inspects the presence or absence of density unevenness contained in a video signal of an inspection target such as an imaging device, which quantizes the video signal from the inspection target that captures an image of a reference white light source and performs X×Y a partial area extracting means for extracting a preset area of the area of the storing means; a marginal distribution calculating means for calculating a marginal distribution of concentration for each extracted partial area; a change calculation means for calculating the amount of change in the peripheral distribution of each partial area; and if the calculated amount of change in the peripheral distribution of each partial area is greater than or equal to a preset value, the area is determined to be an uneven density area; 1. An image quality inspection device comprising: determination means for determining the quality of an image. (2) The image quality inspection device according to claim 1, wherein the partial area extracting means extracts strips in two directions, vertical and horizontal. (3) The image quality inspection apparatus according to claim 1, wherein the change amount calculation means is expressed by the sum of products of differential values.