JPS6238988A - Correction device for illuminance unevenness - Google Patents

Abstract

PURPOSE:To obtain a binary-coded signal representing correctly an object to be recognized by providing a threshold memory that generates a threshold corresponding to the brightness of illumination on the object to be recognized at a threshold setting means. CONSTITUTION:An X-Y table 5 is moved so that the part A to be recognized of an object 3 to be recognized is image-formed at a center 12 on the image forming area 1a of an image pickup element 1, and a picture signal is written on a picture data memory 7 through a binary-coded circuit 6 and also, is stored on a memory within a picture process part 8 as a reference pattern. Next, the part A to be recognized is shifted to an original point 13 moving the X-Y table 5, and calculating the threshold having the best matching characteristic with the reference pattern against the image-formed part A to be recognized, it is written on a threshold memory 9. Following that, it is shifted in the same operation as the scan of a scanning line, the optimum threshold of the whole image-forming area 1a can be obtained. At the next, the content of the threshold memory 9 is impressed on the binary-coded circuit 6, and also, picture data impressed on it, and through the picture data memory 7, it is outputted after a prescribed conversion process at the picture process part 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an illuminance unevenness correction device for correcting illuminance unevenness in an image processing device.

[Conventional technology]

FIG. 3 is a typical schematic configuration diagram showing a conventional image processing apparatus that recognizes whether characters are correctly stamped at the correct position on an object to be recognized.

In the figure, (/) is the image sensor, (c) is the V lens (3) for focusing the light to the image sensor (1), which will be described later, is the object to be recognized, and (ql is the object to be recognized (,?) It is a light source that provides light to the

Furthermore, although not shown in the first drawing, in the image processing apparatus shown in FIG.

A means for changing the threshold value of the processing circuit in accordance with the image signal level of the image sensor is employed.

The conventional image processing device is configured as described above, and the object to be recognized (3) is brightly illuminated by light from the light source (4=1). The passed light enters the image sensor (C) with a distribution corresponding to the reflection intensity of the letters ABC and the background.The image sensor (1) sequentially receives this reflected light on its light receiving surface. This light-receiving surface is scanned by a synchronizing signal and converted into an image signal, that is, an electrical output signal, and this image signal is sent to an image processing section (not shown).

[Problem that the invention seeks to solve]

With conventional image processing devices, when a character is accurately printed and the printing density is the same throughout, the image signal level of one character should be uniform, but in reality, the illumination characteristics of the light source and the lens Due to mutual influences such as the optical characteristics of the image pickup device and the sensitivity characteristics of the image pickup device, the signal level changes depending on the position where the image is formed on the image pickup device even for characters of the same density. Furthermore, in the above-mentioned case, if you simply binarize with a single fixed threshold value, due to the influence of each of the characteristics mentioned above, the image will be formed at the center position of the image sensor and at a peripheral position shifted from the center. The 1:l value conversion signal changed from when the image was read, and the image was observed as different from the characters printed on the object to be recognized. Furthermore, if the latter method in the conventional configuration described above is adopted, the threshold value changes depending on the history of the image signal of the image sensor. The problem was that it was not represented in the

This invention was made to solve the above-mentioned problems, and it is possible to accurately represent the object to be recognized regardless of uneven illuminance, no matter where the image of the object is formed on the image sensor. The purpose is to obtain a co-valued signal.

[Means for solving problems]

In the illuminance unevenness correction device according to the present invention, a threshold value memory for threshold data is provided in the threshold value setting means, and a threshold value for correcting illuminance unevenness determined in advance by an image processing unit is stored in advance in this threshold value memory. The threshold value for sequentially extracting one image when reading one image is made variable.

[For production]

In the illuminance unevenness correction device according to the present invention, the output of approximately the center of the object to be recognized obtained by the image sensor is stored as a reference pattern in the image processing unit using a bottom value signal, and a threshold value that is consistent with this reference pattern is imaged. The threshold value is calculated by the image processing unit in the entire area of the element, and after storing this threshold value in the threshold value memory, when reading one image, the illuminance unevenness is corrected by the threshold value of the deformation taken out sequentially, and the image of the object to be recognized is can be expressed accurately.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the figures.
The figure is a schematic configuration diagram partially showing a block diagram of an image processing device including an illuminance unevenness correction device of the present invention. In the figure, (1) is an image sensor, (, 2) is a lens placed in front of this image sensor (1), (3) is an object to be recognized that faces this lens (2), and (4) is a light source that illuminates the object to be recognized (3), and (S) is an
Y table, [t] is a co-value conversion circuit for converting the image signal output from the image sensor (1) into a U-value conversion signal, (7
) is an image data memo IJ connected to the binarization circuit (6) to store the 2@ conversion data, (g'1 is an image data memo IJ connected to the image data memory (4) and used to perform various image processing. A processing unit (9) is a threshold memory that stores threshold data applied from the image processing unit (rl); (10)
is connected to the image sensor (c, This is Sobe.

Incidentally, the above-mentioned co-value converting circuit C6) 1 image data memo January 7).

The image processing unit (t), threshold value memo IJ (?1, etc.) constitute a threshold value setting means (//).

In the illuminance unevenness correction device configured as above,
First, by 1 manual operation, the recognized part (
Operate the drive motor (not shown) to position the X-Y table ( The image signal of the image sensor (1) at this time is written to the image data memory (7) via the λ value conversion circuit (6), and the image signal of the image sensor (1) near the center of the image sensor (1) is written to the image data memory (7). The @ pattern is used as a reference pattern in the memory (
(not shown).

Next, in response to the tilting signal from the control unit (10), the X-Y table (stage) is moved so that the recognized part C of the recognized object (3) is aligned with the image sensor (1) shown in FIG. When it is moved to the origin position indicated by the symbol (/3) in the imaging area (/a).

The threshold value that has the best consistency with the previously stored reference pattern for the recognized part (Al) imaged at this origin (/3) is determined by the image processing unit Ig, and the threshold value in the threshold memory (9
) is written to. This threshold value writing operation needs to be performed over the entire imaging area (/a) of the image sensor (1), and the X-Y table (S) is
), the optimum threshold value for the entire imaging area (/a) can be determined by moving it as indicated by the symbol (Al...) in Figure 2 using the same operation as the scanning operation of the scanning line. can get.

Next, after one or more threshold value writing operations are completed, when performing a normal recognition operation, the contents of each threshold value ij are written into the threshold value memory (9) in synchronization with the scanning cycle of the image sensor (1).
In addition to applying the voltage to the λ value converting circuit Al, this λ value converting circuit (6
) is applied with image data based on the image of the object to be recognized (3), and image signals based on the threshold values of the λ value conversion circuit (Al) are written into the image data memory (4). ) is image data that has already been corrected for illuminance unevenness, and the image processing unit (r) performs a predetermined conversion process using the data and outputs the processing result to a display device (not shown). The person can see an image having exactly the same shading as the recognized part (sword) formed on the recognized object (3).

〔Effect of the invention〕

As described above, according to the present invention, before recognizing the object, a threshold value for correcting illuminance unevenness on the object to be recognized is determined in advance, this threshold value is stored in the threshold value memory, and then the image sensor is used during normal recognition processing. By outputting the contents of the threshold memory to the λ value converting circuit in synchronization with the scanning operation of This has the effect of allowing good image processing. Furthermore, the time required to design and adjust the optical system can be greatly reduced.

[Brief explanation of the drawing]

FIG. 1 is a partial block diagram showing an image processing apparatus including an embodiment of the present invention, and FIG. 2 shows the operation of an X-Y table when creating threshold data in an embodiment of the present invention. FIG. 3 is a diagram schematically showing the main parts of a conventional image processing apparatus. (C is the image sensor, (3) is the object to be recognized, (!rl is X-
Y table, (t) is a λ value conversion circuit, and (7) is an image data memory. (fl is the image processing unit, (9) is the threshold memory, and (10) is the mlJl unit. In the figure, the same reference numerals indicate the same or equivalent parts.
−family ho

Claims (4)

[Claims] (1) In a device that binarizes an image signal obtained by an image sensor using a threshold value from a threshold value setting means, the threshold value setting means sets a threshold value according to a brightness distribution of illumination on an object to be recognized. An illuminance unevenness correction device characterized by having a threshold value memory for generating. (2) The threshold value setting means has an image processing unit for storing an image signal output of the object to be recognized obtained by the image sensor as a reference pattern through a binarization circuit, and The illuminance unevenness correction device according to claim 1, characterized in that the image processing unit determines a threshold value that is consistent with the reference pattern, and stores this threshold value in the threshold memory. . (3) The illuminance unevenness correction device according to claim 2, further comprising an image data memory for writing an image signal from the image sensor through the binarization circuit. (4) The illuminance unevenness correction device according to claim 1, further comprising an X-Y table controlled by a control unit to move the object to be recognized in the X-Y direction.