JPH02182078A - Binarized picture input signal correction circuit - Google Patents

Abstract

PURPOSE:To discriminate the propriety of a picture accurately even lightness of an object is ununiform by inputting once a signal representing only the lightness of the object to a correction memory, comparing the signal with a picture signal for each picture element to obtain a corrected binarized data. CONSTITUTION:With a switch 3 thrown to the position 1' at first, an object such as a liquid crystal display device having no object to be tested as a character or a symbol is picked up by a video camera 1 to obtain a signal representing only the lightness of the object. The picture analog signal is converted into an n-bit digital signal by an A/D converter 2 and stored in a prescribed address of a correction memory 4 in response to the address output of a counter 7. Then the switch 3 is thrown to the position 2', the object having the sample 10 be tested is picked up by the video camera 1, the picture analog signal is converted into an n-bit digital signal by the A/D converter 2 and the digital signal is inputted to a B input of a digital comparator 5. Simultaneously, a correction signal representing only the lightness of the object stored in the correction memory 4 is inputted to an A input of the digital comparator 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a correction circuit for a binary image input signal of a subject with non-uniform illumination light, and in particular, the present invention relates to a correction circuit for a binary image input signal of a subject with non-uniform illumination light, and in particular, the present invention relates to a correction circuit for correcting a binary image input signal of a subject with non-uniform illumination light. The present invention relates to a binarized image input correction circuit that can accurately determine an image by removing .

[Conventional technology]

Recently, with the development of image processing technology, it has become possible to inspect various test objects by converting image signals using a video camera and digitally processing the signals. For example, video cameras have come to be used instead of visual inspection to check whether symbols such as various letters and numbers displayed on a liquid crystal display such as a camera are accurate. In this case, the image signal representing the symbol on the liquid crystal display is compared with the boundary value for each pixel, a binary signal is created corresponding to whether or not there is an image in each pixel, and the image is determined based on this. There is.

[Problem to be solved by the invention]

However, the brightness of the illumination light on the subject is not always constant, and may be affected by reflections from nearby mechanical equipment, human movement, or a decrease in the illumination light due to deterioration of the lighting equipment itself. The brightness of the illumination light varies. In order to completely prevent this, it is necessary to ensure that the brightness of the subject does not change due to the large number of lighting equipment. However, this has the problem of requiring a large-scale lighting device.

Therefore, an object of the present invention is to provide a binarized image input correction circuit that can eliminate the influence of fluctuations in the brightness of illumination light on a subject without requiring a large-scale illumination device. .

[Means to solve the problem]

As a result of intensive research for the above purpose, the present inventor has determined that in order to remove the influence of the brightness of the illumination light on the subject from the image signal,
The inventors have discovered that a binary image input signal can be created by comparing an image signal with a signal indicating only the brightness of illumination light on a subject, and have come up with the present invention.

That is, the binarized image input correction circuit of the present invention is a circuit that corrects a binarized image input signal according to the non-uniformity of the brightness of the illumination light on the subject. By comparing the image signal of the subject and the correction signal from the correction memory, a signal representing a state in which the influence of the brightness of the illumination light on the subject is removed from the image is obtained. , a digital comparator that outputs the correction method binary data, and a binary data memory that stores the correction method binary data.

[Examples and effects]

FIG. 1 shows a binarized image input correction circuit according to an embodiment of the present invention.

In the binarized image input correction circuit of the present invention, the video camera 1 that photographs a subject and outputs an image analog signal is
It is connected to an A/D converter 2, and the output of the A/D converter 2 is connected to a switch 3.

The switch 3 can be switched between ■ and ■, and when the switch 3 is turned to the ■ side, the digital signal from the A/D converter 2 is input to the correction memory 4. Further, the input terminal A of the digital comparator 5 is connected to the terminal (2) of the switch 3, and the input terminal B is connected to a line branched between the A/D converter 2 and the terminal (2) of the switch 3. Further, the output of the digital comparator 5 is connected to a binary data memory 6.

On the other hand, the clock signal input line is connected to the A/D converter 2 and also to the counter 7, and the address output line of the counter 7 is connected to the correction memory 4 and the binarized data memory 6, respectively. ing. Further, the input line of the read/write (R/W) signal is connected to a circuit (not shown) for operating the switch 3, a correction memory 4, and a binary data memory 6, respectively. Further, the clear signal input line is connected to the counter 7.

In the circuit configured as described above, correction of the binary image input signal is performed as follows. First, with the switch 3 turned to ■, a test object, such as a liquid crystal display without characters or symbols, is photographed by the video camera 1, and a signal representing only the brightness of the object is obtained. As shown at 8 in FIG. 2, the signal representing only the brightness of the object is composed of signals representing the brightness of each pixel constituting the object IO. For example, set the subject 10 to
n and 0 to m to create mxn pixels of Aoo to Amn, and a signal representing the brightness of each pixel is obtained from the video camera 1 as an image analog signal.

This image analog signal is converted to n by the ^/D converter 2.
It becomes a bit digital signal and is stored at a predetermined address in the correction memory 4 according to the address output of the counter 7.

Next, turn the switch 3 toward ■, photograph the subject with the test object using the video camera l, convert the image analog signal into an n-bit digital signal through the ^/D converter 2, and output it to the digital comparator 5. Enter. At the same time, a correction signal representing only the brightness of the subject stored in the correction memory 4 is input to the digital comparator 5 A. Here, as shown in FIG.
corresponds one-to-one with a signal representing only the brightness of For example, the signal of pixel Akl, which is a signal representing only the brightness of the subject 10, corresponds to pixel Bkl of the image signal, so Akl and Bk
By comparing l, the presence or absence of an image can be determined.

Here, in order to completely eliminate the influence of the brightness of the subject 10 and to accurately determine the presence or absence of an image, the correction signal from the correction memory 4 is input to the digital comparator 5 at a level of 1/2. is preferable. By doing so, the correction signal from the correction memory 4 will be located between the case of "with image" and the case of "no image" of the image signal.

As a result, if we focus on pixels Akl and Bkl, for example,
If there is no image for the subject, Bki! >A) Cj! Therefore, if there is an image, Bki''<Aki'. Therefore, the presence or absence of an image can be accurately determined.

The output of the digital comparator 5 is corrected binary data, and the image of the subject 10 is displayed depending on the presence or absence (H or L) of the image at each pixel. The corrected binarized data is stored in the binarized data memory 6, and a decision circuit (not shown) decides whether or not the image in the subject 10 is appropriate. When the image determination is completed, the counter 7 is cleared by a clear signal, and inspection of another object is started.

As detailed above, in the binarized image input correction circuit of the present invention, a signal representing only the brightness of the subject is once input into the correction memory, and this signal is compared with the image signal for each pixel. Since the corrected binarized data is obtained, even if the brightness of the subject is uneven, it is possible to accurately determine whether the image is suitable or not.

In addition, since the correction signal from the correction memory 4 is input to the digital comparator 5 at a level of 172, when comparing the image signal with a signal representing only the brightness of the subject, an error will occur in determining the presence or absence of an image. Never.

〔Effect of the invention〕

As described in detail above, the binarized image input correction circuit of the present invention performs correction for each pixel, so the accuracy of the binarized data is significantly improved. Furthermore, by obtaining correction data at an appropriate time, it is possible to cope with changes in illumination over time.

By using the binarized image input correction circuit of the present invention having such characteristics, accurate image determination can be performed without requiring a large-scale illumination device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a binarized image input correction circuit according to an embodiment of the present invention, and FIG. 2 shows a state where an object is divided into pixels, and A is a case where there is no object. B is a case with a test object. 1...Video camera 2...^/D converter 3...Switch 4...Correction memory 5...Digital comparator 6...Binarization data memory 7...Counter 10...Subject

Claims (2)

[Claims] (1) A circuit that corrects a binary image input signal according to the non-uniformity of the brightness of the illumination light on the subject, and a correction memory that stores a signal representing only the brightness of the illumination light on the subject;
A digital camera that outputs, as corrected binary data, a signal representing a state in which the influence of the brightness of the illumination light on the subject is removed from the image by comparing the image signal of the subject with the correction signal from the correction memory. A circuit comprising a comparator and a binarized data memory that stores the corrected binarized data. (2) The binarized image input correction circuit according to claim 1, wherein a signal having a level 1/2 of the correction signal is input to the digital comparator.