JPH0225555B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a demodulation method for an optical character reading device.
In particular, it relates to a demodulation method for optical character reading devices that removes noise information.

An optical character reader (OCR) irradiates light onto characters, symbols, numbers, etc. (hereinafter referred to as characters) written on a medium, and converts the reflected light (or transmitted light) into electricity using a photodetector. Characters are read based on signals.

This electrical signal is once stored in video storage (hereinafter referred to as memory) and then read out, but the characters written on the medium may be faded or missing, and these incomplete character patterns remain in the memory. Since the data is stored, there is a drawback that if reading processing is continued as is, characters may be misrecognized.

The present invention has been devised in view of the above, and an object of the present invention is to provide an OCR that corrects character data read from a medium and reduces misrecognition of characters.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

Before explaining the embodiments, the basic idea of the present invention will be explained.

As shown in Figure 1, "4" and "2" are stored in memory M.
Pattern information such as the following is stored.

Since the character size written on the medium is determined to be within a certain standard value, by calculating the size of the segment representing the character information stored in the memory M, it can be determined whether the character information is true or not. It can be determined whether For example, in Fig. 1, information O ₁ and O ₂ representing a blemish is stored near the character "2", but in this case, the width measurement that measures the width of the information segment within the one character storage area R ₁ is of the memory contents for each column.
The width of the information segment representing the black art book can be counted by performing an OR operation and inputting the resulting calculated value into a register. The widths of the information segments J ₁ J ₃ J ₅ in the region R ₁ are 3 bits long, 10 bits long, and 2 bits long. Therefore, the total width of the information segment is 3
Bit + 2 bits + 10 bits + 2 bits + 2 bits = 19 bits, which is larger than the standard value _WN , so
It can be seen that information other than character information (stain information) is included.

For this reason, first, the width of segment _J1 located at the left end is checked, and if the width is less than a certain value Wn, for example 2 bits, it is determined that it is not character information. Next, when we examine the total width of the information segment excluding those that are not text information, we find that it is 10 bits + 2 bits + 2 bits = 14 bits, which is still larger than the width standard value _WN , so the width of segment _J5 located at the right end is investigate. If this segment width is less than the specified standard value Wn, it is treated as non-character information, if it is larger than the standard value, then the segment width located on the left side is checked, and if it is smaller than the standard width Wn, this information is treated as non-character information. If the segment width located on the left side is larger than the standard value Wn, the segment widths located on the right and left sides are compared and the wider segment is treated as valid (character information).

The height of this information pattern in memory M is then measured. The height can be measured in the same way as the width measurement described above, and the storage area can be measured line by line.
The height of the information pattern obtained by performing an OR operation and inputting the resulting calculated value into a register is sufficient.

For example, the height of the segment in region _R1 is
h ₁ , h ₂ , h ₃ , and the total height H of the information pattern is h ₁
+b ₁ +h ₂ +b ₂ +h ₃ , and if the total height H is larger than the standard value _HN for the height of the information pattern, it is determined that non-text information is included, and the height of the segment at the top Compare h ₁ with the standard value Hn of the segment.

If h ₁ < Hn, this information segment is determined to be non-text information, the total height of the remaining information segments is checked, this total height H ₁ is compared with the standard value H _N , and H ₁ < H _N
Then, this remaining information segment is determined to be character information. If H ₁ > H _N , it is determined that the remaining information segments still contain non-text information, and the height h ₅ of the lowest information segment is checked, and h ₅ is compared with the standard value Hn. If H ₅ < Hn, the information segment h ₅ at the lowest level is treated as non-character information, and h ₅
>Hn, the height _h5 of the lowest information segment is compared with the height _h3 of the information segment described above, and the information segment with the larger height is treated as valid (character information). After this, the total height of the remaining information segments is compared with the standard value H _N , and if it is larger than the standard value H _N , the above-mentioned operation of checking the height of the highest information segment among the remaining information segments is performed again. I'll return it.

If H ₁ > H _N , compare the heights of the lowest information segments, remove the information segment with the lower height as invalid (non-text information), check the total height of the remaining information segments, and set the default value. H _N is compared, and it is determined whether or not it is character information by the same operation as described above. In this way, noise information is deleted and only text information is selected.

FIG. 2 is a configuration diagram of an embodiment of the present invention, and shows M
is video storage (memory), A is address register, R ₁ R ₂ is OR circuit, L ₁ L ₂ L ₃ is register,
K ₁ K ₂ is a counter, C ₁ C ₂ is a comparator, L ₄ is a register in which a standard value is set, and S is a control section.

Next, the operation of this device will be explained.

Character information in one byte of the storage area _M11 of the memory M specified by the address signal of the address register A is inputted in parallel from the memory M to one input terminal of the OR circuit _R1 . One byte of data from register _L1 is input in parallel to the input terminal on the other side of OR circuit _R1 , but the initial values of register _L1 are all set to "0", and OR circuit _R1 The output of is the data itself of area _M11 . This 1-byte data is input to register _L1 . Next, 1 byte of data in area _M12 of memory M specified by the address signal of address register A is
The data input to one input terminal of OR circuit R ₁ and the data of register L ₁ input to the other input terminal are
An OR operation is performed and its output is input to register _L1 . At this time, the data previously stored in register _L1 is cleared in advance.

When the OR operation of the data in areas M ₁₁ to M _o1 of memory M is completed by repeating such operations,
One byte of data stored in register _L1 is input to area _L21 of register _L2 . Next, by similar operation, the area M ₂₁ ~ in the second column of the memory M is
An OR operation is performed on the data in M _2o , the result of the operation is stored in area L ₂₂ of register L ₂ , and the same operation is performed to store the data in the area of the third column...the m-th column.
The OR operation result is stored in _L23 ... _L2n of register _L2 . In this way register L ₂ has memory M
A group of bits indicating black pixel information (segment J ₁ ~
J ₅ ) is obtained.

Next, after the measuring section K measures the "length" from the first segment to the final segment stored in the register _L2 , this measured value _W0 is sent to the comparator _C1.
The standard value Wn is input to one input terminal, and the standard value Wn is input to the other terminal, and compared with this.

If W ₀ W _N , the output of comparator C ₁ becomes L (low) level, and the first bit of flag register L ₅ is “0”; if W ₀ > W _N , the output of comparator C ₂ becomes H (high).
level, and the first bit of flag register _L5 becomes '1'.

If W ₀ W _N , then the measurement operation in the height direction of the character information is performed. However, if W ₀ >W _N , the lengths of segments J ₁ J ₅ at both ends of the segments stored in register L ₂ are compared.

Then, among these segments, the one with the shorter segment length is invalidated, the width of the pattern made up of the remaining information segments is measured, and the counted value W ₁ is inputted to the comparator C ₁ , and the standard value W _N is calculated. compare.

This operation is then repeated until the segment width becomes equal to or less than the standard value _WN .

Then, when the segment width becomes equal to or less than the standard value _WN , the pattern height is next measured, and this measurement method is the same as the pattern width measurement method.

First, the OR circuit _R2 performs an OR operation on the data of the corresponding bits in the areas _N11 to _N1l of the first row of the memory M, and transfers the operation result stored in the register _L3 to the register _L4 , and the same applies hereafter. In this way, the OR operation is performed for the second row, . . ., the nth row, respectively, and the results are stored in the area of register _L3 . After that, the pattern height is measured by measuring part _K2 ,
Input the measured value H ₀ of the measuring section K ₂ to one input terminal of the comparator C ₂ , and the standard value input to the other input terminal.
Compare with _HN .

If H ₀ < H _N , pattern data existing in this area is valid; if H ₀ > H _N , segments existing at both ends are valid.
Measure the segment heights of h ₁ and h ₅ with counter K ₂ ,
Compare with comparator _C1 . The segment data with the lower segment height among these will be invalidated,
The remaining pattern height (used as noise data) is measured by the measurement unit K ₂ , and the measured value is input to one input terminal of the comparator C ₂ , and the standard value H _N is input to the other input terminal. Compare with. Repeat this operation until the pattern height becomes less than the standard value _HN .

The data within the segment area _SW in the pattern width direction and the segment area _SH in the pattern height direction obtained as described above is treated as character information.

As is clear from the above description, the demodulation method of the optical character reading device according to the present invention, after reading characters written on a medium, converts only data within predetermined standard dimensions into data representing characters. In addition, for data that is outside the standard dimensions, the segments on both ends of the projection of the data are deleted and the data is placed within the standard dimensions, so dirt, etc. attached to the medium is removed, and image characters with clear outlines are created. It has the advantage of providing a pattern.

[Brief explanation of drawings]

FIG. 1 is a diagram showing how characters read from a medium are stored in a memory, and FIG. 2 is a configuration diagram of an embodiment of the present invention. A...address register, M...memory, _R1 ,
_R2 ...OR circuit, _L1 to _L4 ...Register, _C1 , _C2 ...
...Comparator.

Claims (1)

[Claims] 1. Reading characters written in a unit area of a medium,
In an optical character reading device that stores the reading pattern in a memory and recognizes characters on the medium based on signals in the memory, Then, calculate the logical OR of the storage information of the storage area in each unit area, take the projection in the width direction and height direction of the unit area, calculate the width and height of the pattern in the unit area, and calculate the width and height are compared with standard values, and patterns within the range of the standard values are considered valid; for patterns within the unit area whose width and height are outside the range of the standard values, the width and height are The present invention is characterized in that an extraction circuit is provided for removing from both ends of the projection one or more projection portions that keep the width and height of the pattern within standard values from a plurality of projection portions in the projection in the height direction. Demodulation method for optical character reading devices.