JPH0460888A - Picture processor - Google Patents

Abstract

PURPOSE:To attain normal correction even in case that a sheet of paper is carried as being skewed by updating reference level information by gradation level information, and correcting picture information on the basis of the stored reference level information. CONSTITUTION:The contents of the reference level information is updated by the gradation level information, and simultaneously, the picture information generated by a picture information generating means is corrected on the basis of the stored reference level information. Namely, the image sensor 7 of an input part 1 moves by the portion of the width of a picture element to the direction of an arrow mark in relation to a business form 6, and scans next one line portion, and gradation data of the obtained picture information is inputted to a shading correcting part 5, and simultaneously, a data comparing part 3 compares white level data stored in a white level memory 2 and the gradation data with each other, and stores the data of a larger level newly in the address of the white level memory 2. Thus, even in case that the sheet of paper is carried as being skewed, shading correction can be normally performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to an image processing apparatus, and particularly to a preprocessing section of an image processing apparatus.

(Prior Art) An image processing device is a device that reads images on paper, and is widely used as a computer peripheral device such as an optical character reading device.

In order to correctly recognize an image, such an image processing apparatus is provided with a preprocessing section that performs various corrections as a step before the image recognition section.

One of this pre-processing parts is a shading correction part,
Make the following corrections.

Generally, in an image processing apparatus, light from a light source is irradiated onto a sheet of paper. The reflected light of the light irradiated onto the paper is collected by a lens and received by a sensor. The gradation as image information received by the sensor is converted into an electrical signal and sent to the recognition unit.

However, the light emitted from the light source has a difference in brightness (light amount) between the center and the edges of the paper.

A shedding correction section is provided to correct such a difference in brightness.

By the way, in a conventional shading correction section, shading correction is performed using gradation information in image information as a reference for correction when scanning the leading edge of a sheet.

However, the conveyance path of image processing devices is generally black, and if the paper is conveyed skewed or the leading edge of the paper is damaged, the gradation level of the conveyance path is read instead of the paper. Since the reference level was used, correction could not be performed normally.

(Problems to be Solved by the Invention) As described above, conventional image processing apparatuses have a problem in that when paper is conveyed in a skewed manner or when a part of the paper is missing, shading correction cannot be performed normally. Ta.

The present invention was devised to solve these drawbacks, and it is an object of the present invention to provide an image processing device that can perform normal shading correction even when paper is conveyed in a skewed manner or when a part of the paper is lost. With the goal.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, an image processing apparatus of the present invention includes an image information generation means for scanning an image and generating image information; storage means for storing a plurality of gradation information in the image information generated by the generation means as reference level information; and reference level information stored in the storage means each time an image is scanned by a predetermined line. and gradation information in the image information generated by the image information generation means for each corresponding pixel; information updating means for updating the content of the reference level information with the gradation level information when representing the gradation level;
The image forming apparatus is characterized by comprising a correction means for correcting the image information generated by the image information generation means based on the reference level information stored in the storage means.

(Function) In the image processing apparatus of the present invention, when abnormal reference level information is stored in the storage means, this reference level information is updated to normal reference level information when scanning a sheet.

Therefore, according to the present invention, shading correction can be performed normally even when the paper is conveyed in a skewed manner or when a part of the paper is lost.

(Example) An example in which the image processing device of the present invention is applied to an optical character reading device will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the optical character reading device of this embodiment.

In the figure, reference numeral 1 denotes an input section as an image information generating means for scanning a form and performing photoelectric conversion to obtain image data.

Reference numeral 2 denotes a white level memory section as a storage means for storing gradation level data in each bit of image data for one line scan inputted from the input section 1 as white level data as reference level information.

Reference numeral 3 denotes a data comparison section that compares the white level data stored in the memory section 2 and the gradation data inputted from the input section 1.

Reference numeral 4 denotes a memory control unit as an information updating means for storing data with a higher level in the memory unit 2 in the comparison unit 3.

Reference numeral 5 denotes a shading correction unit that performs shading correction on input data based on the own level data stored in the memory unit 2 and outputs the corrected data to a character recognition unit (not shown).

FIG. 2 is a diagram for explaining the operation when reading a form by the scanning section of the input section 1.

In the figure, 6 is a form to be read.

7 is an image sensor that scans the surface of the form 6. 8
are pixels of the image sensor 7, and n pixels are provided on the image sensor 7 in a straight line.

Next, the operation of the optical character reading device of this embodiment will be explained.

First, an image of one scanning line of the form 6 is input to the image sensor 7 of the human power section 1, and gradation data D11, D12, . . . , Dln corresponding to each pixel is generated.

This image data D11, D12, . , An as white level data which is reference level information.

Next, the image sensor 7 of the input unit 1 detects the second
It moves by the width of the pixel in the direction of the arrow shown in the figure, and scans the next one line.

Tone data D in the image data obtained by this scanning
21, D22, .

The data comparison section 3 compares the white level data Dll, D12, ... Dln stored in the white level memory 2 with the gradation data D21, D22, ..., D2n, and selects the one with the higher level. data is newly stored in addresses AI, A21, and An of the white level memory.

Image data D obtained in the same manner at the m-th line scan
ml, Dm2, . . . , Dmn and the data stored in addresses AI, A2, . ..., stored in An.

In this way, the brightest gradation data among the input gradation data is stored in the white level memory 2 as white level data.

On the other hand, the shading correction section 5 performs shading correction on the gradation data output from the human power section 1 based on the updated white level data.

The shading-corrected image data is sent to a character recognition section (not shown).

The operation when the form 6 is conveyed in a skewed manner as shown in FIG. 3 will be described next.

In the first scan, the gradation data of the form 6 is used as the white level data for the pixels in the range A of the image sensor 7, or the gradation data of the form conveyance path is used as the white level data for the pixels in the range B. Data will be accepted.

However, as the image sensor 7 scans the form 6, the gradation data of the form conveyance path is updated to the gradation data of the form 6 one after another.

Therefore, from the position indicated by the dotted line in the figure, shading correction is performed based on correct white level data.

FIG. 4 is a diagram showing a case where there is a missing part 9 in a part of the form 6. In this case as well, as explained using FIG. shading correction is performed.

In this embodiment, the gradation data in the image data is compared with the own level data stored in the white level memory every time one line is scanned, but the comparison may be made every few lines.

[Effects of the Invention As explained above, according to the image processing device of the present invention,
Shading correction can be performed normally even if the paper is conveyed in a skewed manner or if part of the paper is missing.

[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 diagram showing an image sensor and a form, FIG. 3 is a diagram showing a form skewed and conveyed, and FIG. 4 is a partial diagram. FIG. DESCRIPTION OF SYMBOLS 1... Input section, 2... White level memory, 3... Data comparison section, 4... Memory control section, 5... Shading correction section. Applicant: Toshiba Corporation

Claims (1)

[Scope of Claims] Image information generation means for scanning an image and generating image information; and storage means for storing a plurality of gradation information in the image information generated by the image information generation means as reference level information. , Every time the image is scanned by a predetermined line, the reference level information stored in the storage means and the gradation information in the image information generated by the image information generation means are calculated for each corresponding pixel. a comparison means for making a comparison; and an information updating means for updating the contents of the reference level information with the gradation level information when the gradation level information represents a brighter gradation than the reference level information in the comparison means; An image processing apparatus comprising: a correction means for correcting the image information generated by the image information generation means based on the reference level information stored in the storage means.