JPH0778820B2 - Image processing method - Google Patents

Description

The present invention relates to an image processing method for automatically reading and processing document image information.

[Prior Art] FIG. 10 shows a character recognition process of a conventional character recognition device of this type.

As shown in step S81, the characters on the manuscript paper P are read out character by character and photoelectrically converted, and this is further converted into a binary data pattern of "1" and "0" in step S82. In a succeeding step S83, pre-processing for making the later-described processing effective, that is, noise processing such as black spots on the paper P on which characters are recorded based on the binarized pattern in step S82 and a character graphic boundary. A series of processing including surface smoothing is performed. Next, in step S84, a feature extraction process is performed to extract some features (intersection points, branch points, the number of loops, stroke length information, etc.) necessary for character recognition. Depending on the extraction result, some characters having common characteristics are selected from many characters. Next, step S8
When the number is 5 or less, the dictionary matching process and the recognition process are performed as the identification process for selecting the only character from among them.

First, it is checked whether or not the dictionary can be guided (searched) according to the features extracted in step S85. If the feature extracted here is not enough to guide the dictionary, the process proceeds to step S88, and unrecognizable is output. On the other hand, if the dictionary can be guided by the extracted feature points, the built-in dictionary is searched in step S86, and the extracted features are sequentially compared with the extracted features. If the result of collation in step S87 is a match, step S88
Outputs the matching result as a recognition output. If no match is found, it is output as unrecognizable.

[Problems to be Solved by the Invention] However, according to the conventional recognition method, the complicated processing described above is performed even in the case of only simple characters (characters that are easily recognized), alphabet letters, and numbers. It has the drawback of taking too much processing time.

In addition, the configuration for realizing the above processing is complicated, and cost up has various problems in terms of reliability.

[Means for Solving Problems] The present invention has been made in view of the problems of the above-described conventional technology, and has the following configuration as one means for solving the above problems.

That is, a reading unit that optically reads a document, a dividing unit that divides the document image information read by the reading unit into predetermined regions, and each region divided by the dividing unit appear on a predetermined number of lines. A detection unit that detects the number of groups of consecutive black pixel groups and a determination unit that determines the minimum value of the number of groups detected by the detection unit as the representative value of the area.

[Operation] In the above configuration, image information obtained by optically reading a document is input, the input image information is divided into predetermined regions, and each divided region appears on a predetermined number of lines. By detecting the number of groups of consecutive black pixel groups and determining the minimum value of the number of detected groups as the representative value of the region, accurate pattern recognition processing can be performed in a very short time.

Embodiment An embodiment according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.
Is a reader for reading document image information including keywords by OMR and converting it into an electric signal, 2 is an optical disk for storing the image information read by the reader 1, 3 is a host computer for controlling the entire embodiment, 4 is a keyboard, 5 Is a CRT that displays image information and operation information, and 6 is a printer that prints out image information and the like. Reference numeral 7 is an auto feeder for automatically feeding the originals to the original reading surface of the reader 1 one by one.

In the host computer 3, 50 is a CPU that controls the entire apparatus according to the control program shown in FIG. 4 stored in the ROM 51, and the CPU 50 is preferably composed of, for example, a Microcomputer MC68000 manufactured by Motorola. Reference numeral 51 is a ROM, and the ROM 51 includes a standard feature pattern storage area 51a. Reference numeral 52 is a CRT interface that controls the interface with the CRT 5, 53 is a keyboard interface that controls the interface with the keyboard 4, and 54 is an optical disk interface that controls the interface with the optical disk. Also, 55 is a reader interface that controls the interface with the reader 1, 56 is a printer interface that controls the interface with the printer 6, and 57 is a process history, a read mark recognition process, and the like.
The RAM and 60 are buses that connect the respective components.

The detailed storage area of the RAM 57 is shown in FIG.

In FIG. 2, 21 is a pattern buffer, 22 is a line histogram buffer, and 23 is an area histogram buffer.

FIG. 3 shows an external view of this embodiment having the above configuration.

In the figure, the same numbers are assigned to the same configurations as in FIG. 8
Is an interface cable between the reader 1 and the host computer 3, and 9 is an interface cable between the printer 6 and the host computer 3.

The operation of this embodiment having the above configuration will be described below with reference to the flow chart of FIG.

In FIG. 4 as well, similar to FIG. 10, the process of reading and recognizing the pattern indicated by P on the document set by the reader 1 will be described as an example.

First, in step S1, the CPU 50 activates the reader 1 via the reader interface 55, scans the read document surface, and reads the image data of the document surface.

The original surface is, for example, at the bottom of the OMR sheet shown in Fig. 9. The mark is placed and a type pattern is applied on the mark as shown in FIG. The OMR sheet is used for registering keywords of the electronic file system, inputting telephone numbers of facsimiles, setting the number of copies of an image forming apparatus such as a copying machine, and mode setting such as reduction ratio.

When the format as shown in FIG. 8 is fixed and the characters of the fixed pattern are written on it, the subsequent process becomes simpler. In addition, "A" to "Z" and "1" are shown in FIG.
A fixed pattern of "0" is shown. The basic pattern of the format shown in FIG. 8 is a part of a combination of a "T" character composed of three strokes in the x direction and three strokes in the y direction and a diagonal "X" in two directions.

The case where one character at the mark position on the document surface thus written, for example, "A" is read will be described below as an example.

The signal photoelectrically converted by the reader 1 and read in step S1 is read by the reader interface as shown in step S2.
It is sent to 55, is converted into the digital signal of the binary pattern of "1", "0" by the analog-digital converter built in the reader interface 55, and the converted digital signal is
Input to CPU50. Here, the data is "1" when the black density is detected.

The CPU 50 stores the digital data in the digital input 21 input in this way. In the present embodiment, the character pattern is divided into areas of one character 48 bits × 48 bits, and an example of storing read data in the pattern buffer 21 when “A” is read is shown in FIG.

The CPU 50 divides this digital data into a plurality of predetermined areas in step S3. Then, in step S4, a histogram of the stroke distribution for each of the divided regions in the horizontal direction and the vertical direction is obtained. Specifically, as shown in FIG. 5, the histogram of the stroke distribution of the uppermost line in the horizontal direction (X direction) is "1", the histogram of the fourth line is "2", and the leftmost line in the vertical direction (Y direction) is shown. The histogram of the stroke distribution of the line is "1", and the fifth line is "2". Then, the stroke distribution histogram obtained in step S5 is stored in the line histogram buffer 22 of the RAM 57.

The read pattern is divided into, for example, predetermined areas shown in 1 to 10 of FIG. 6 (A). In each divided area,
Region 1 in FIG. 6 (A) has the pattern shown in FIG. 6 (B), and the histogram of the stroke distribution for each line is
As shown in 51, "1,1,2,2,3,2" is obtained in order from the first line.

Then, in step S6, the minimum value of the histogram for each line in the predetermined area previously obtained is found, and this value is stored in the area histogram buffer 23 of the RAM 57 as a representative value of the area. In area 1, the minimum value of the histogram distribution is "1", and the area histogram buffer 23 has this "1".
Is stored. In this way, the representative value of the histogram is obtained for every area and stored in the area histogram buffer 23. FIG. 6C shows the storage state of representative values in all areas in the area histogram buffer 23.

In a succeeding step S10, the standard pattern stored in the standard feature pattern 51a of the ROM 51 and the read pattern stored in the area histogram buffer 23 are matched. As a result, if a pattern match is obtained in step S11,
In step S12, it is recognized as an input of the pattern for which a match is obtained, and the result is output. On the other hand, if no match is obtained, the process proceeds to step S13, the unrecognizable is output, and the process ends. Then, the reading process of the next pattern is executed again.

The standard pattern of "A" of the input standard feature pattern 51a is the seventh
The pattern shown in the figure matches the read pattern shown in FIG. 6 (C), and the input pattern in FIG. 6 (A) is recognized as the input of "A".

As described above, according to this embodiment, the following effects can be considered in recognizing the character pattern shown in FIG. 5, for example.

By using the minimum value of the stroke distribution in a predetermined area as the representative value, the effect of eliminating the reading of dust or the like, which is an erroneous reading in the area, is included. Therefore, the sixth
As shown in FIG. (B), even if the histogram of the line is changed to "3" due to dust or the like shown in 52 in the area, the minimum value of the histogram is used as the representative value, The influence can be prevented and accurate character recognition becomes possible.

Furthermore, since the amount of collated output is small, the processing time is greatly reduced, and recognition is possible only by collating a small amount of outputs, the pattern of FIG. 6C and the standard feature pattern shown in FIG. .

As described above, the shortcomings in the simple character recognition of the character recognition device can be solved, the processing time required for the simple character recognition can be shortened, and high-speed and highly accurate character recognition can be performed.

Further, it is possible to recognize a fixed pattern (print type) numeral or an alphanumeric character at high speed and with high accuracy.

As described above, according to the present invention, in a very short time,
And accurate pattern recognition processing can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment according to the present invention, FIG. 2 is a detailed configuration diagram of the RAM shown in FIG. 1, FIG. 3 is an external view of this embodiment, and FIG. 4 is a pattern of this embodiment. Recognition control flow chart, FIG. 5 is a diagram showing an example of storing a read pattern in the pattern buffer of this embodiment, and FIGS. 6 (A) to 6 (C) are for explaining the recognition processing of the pattern “A” according to this embodiment. FIG. 7 is a diagram showing a storage pattern of “A” in a standard feature pattern, FIG. 8 is a diagram showing a standard input pattern used in this embodiment, and FIG. 9 is an OMR used in this embodiment. FIG. 10 shows a sheet, and FIG. 10 is a flow chart showing conventional pattern recognition processing. In the figure, 1 ... reader, 2 ... optical disk, 3 ... host computer, 4 ... keyboard, 5 ... CRT, 6 ...
Printer, 7 ... Auto feeder, 50 ... CPU, 51 ... R
OM, 51a …… Standard feature pattern storage area, 52 …… CRT interface, 53 …… Keyboard interface, 54 ……
Optical disk interface, 55 …… Reader interface, 56 …… Printer interface, 57 …… RAM, 60…
… It ’s a bus.

Claims (1)

[Claims] 1. Image information obtained by optically reading a document is input, the input image information is divided into predetermined regions, and continuous blacks appearing on a predetermined number of lines for each of the divided regions. An image processing method comprising detecting the number of groups of pixel groups and determining the minimum value of the number of detected groups as a representative value of the region.