JPS589468B2 - Character reading method - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a character reading device, and in particular, it is capable of extracting and reading only characters of a certain color from characters written with several types of writing instruments of different colors. The present invention relates to a character reading device.

In conventional character reading devices, the writing utensils are usually limited to black pencils, black ballpoint pens, etc., and the color information is... Rather than actively reading this, it was usually used as a drop-out color so that it was not input into the device.

However, in documents that we deal with on a daily basis, it is common practice to write important items in red, or to write corrected sentences in a different color.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a character reading device that allows previously input information to be corrected or further information to be added by reading only characters of a specific color.

Below, we will briefly discuss color theory.

Generally, to express the color of each point in an image, the amount of light of the three primary colors (R, G, B) required to equalize the colors (R, G, B) It can be expressed as

Therefore, considering this as a three-dimensional vector, as shown in Figure 1 (
If we consider a space defined by vectors in three directions: 1,0,0), (0,1,0), and (0,0,1), each color can be represented by a vector from the origin.

Further, if the coordinates of the intersection of this vector and the plane represented by R+G+B=1 are (r, g, b), then there is the following relationship between them.

The other (r, g, b) is called the chromaticity coordinate of each color, and each color can be positioned on the (r, g) plane coordinates as shown in FIG.

In FIG. 2, colors closer to red are located near point A, colors closer to green are located near point B, and colors closer to blue are located near the center of origin.

As is clear from the above results, if you want to extract only the information written with one chromaticity coordinate Co (ro, go) of a certain color, the above r, g,
Calculate b. It can be seen that it is better to determine whether it is near Co on the (rtg) plane and quantize to 1 if it is near, and quantize to O if it is not.

Conventionally, color information has been extracted using this method, but in the case of actual characters, the characters are blurred or distorted, and with the quantization method described above, the characters are cut into pieces. There is a risk of it getting lost.

In addition, in order to avoid this, if you widen the range that is judged as 1 on the chromaticity coordinate, it will pick up characters of other colors or background noise, and even unnecessary information will be picked up. There is a risk that it will become binary.

A first object of the present invention is to solve the problems of the prior art as described above, and to reliably quantize only characters of necessary colors.

In addition, the present applicant has previously provided a character reading system for black-colored writing instruments that is resistant to blurring, blurring, and background noise of characters.

(Japanese Patent Publication No. 49-32019. Patent No. 771149) As shown in Fig. 3, this method scans the characters 2 on the record carrier paper 1 with the scanning device 4 through the optical system 3, forming a fine character pattern in the vertical and horizontal directions. , a threshold circuit 5 for discriminating the contrast signal on the divided grid points into black and white binary values using a high threshold value A; The pattern P obtained by the circuit 5 and the pattern Q obtained by the circuit 6 are temporarily stored in two-dimensional registers 7 and 8, respectively.

The pattern P and pattern Q are then processed by the graphic processing circuit 9.
From then, restore the broken character lines of pattern P to connected character lines using pattern Q. A pattern R is created in which black signals due to dirt other than character lines, such as those included in the pattern Q, are removed, and this pattern R is stored in a two-dimensional register 10.

Later on, this method was further cited as a drawback. This improved the complexity of circuits 7 to 10 and provided a simpler character reading system (Japanese Patent Application No. 117876/1983).

This method is shown in FIG. Means 4 similar to Fig. 3 1-6
After obtaining pattern P and pattern Q from 0 to 45,
Pattern P' and pattern Q obtained through the forward connection processing circuit 46 are temporarily stored in a storage circuit 47.

And next. Pattern P' from the memory circuit 47 in the opposite direction.
The pattern Q is read out and passed through the second connection processing circuit 48 to obtain the final output pattern R.

A control circuit 49 controls these sequences.

However, since these inventions are aimed at black and white images, it is impossible to read only characters of a specific color without blurring or blurring.

Therefore, the second object of the present invention is to improve the above invention,
The object of the present invention is to provide a text reading method that can read only characters of a specific color without blurring or blurring by making it possible to target color images.

The present invention will be explained in detail below.

First, the principle of the present invention will be explained with reference to FIG.

The chromaticity coordinates of the color of the specific writing instrument shown in Figure 5 are Co(r
o, go).

At least, the area on the chromaticity coordinates that does not include character components other than this writing instrument and noise components is CA, and the area on the chromaticity coordinates that includes all the character components written with this writing instrument is CB. do.

Then, the chromaticity coordinates of each point are calculated from the color separation signals of each point, and the pattern P1 is obtained by quantizing the coordinates under the condition that they are 1 if they are within CA, and 0 if they are outside CA.

Also, pattern Q1 is obtained by quantizing on the condition that the coordinate is 1 if it is within CB, and 0 if it is outside.

Separately, the brightness signal of each point (in the example, the G component is used as the brightness signal) is quantized with a high threshold so as to not include at least noise components other than characters, and the pattern P
2 is obtained, and further quantized with a low threshold value to ensure that at least the character component is included to obtain pattern Q2.

Then, a pattern P is obtained from the logical product of pattern P1 and pattern P2 and is used as a core pattern, and a pattern Q is obtained from the logical product of pattern Q1 and pattern Q2 and is used as a reference pattern.

Then, by extracting only the connected components of pattern P from pattern Q, a final binarized pattern is obtained.

The present invention will be specifically described below based on Examples.

FIG. 6 is a block diagram showing an embodiment of the present invention, in which characters 61 on a recording medium 60 are scanned by a color scanning device 63 through an optical system 62, and a grid pattern is formed by subdividing the character pattern vertically and horizontally. Obtain color separation signals R, G, B on a point.

Then, from this color separation signal, the chromaticity coordinate calculation circuit 64 calculates the chromaticity coordinate (rag) on the grid point, and determines whether it belongs to a certain area on the chromaticity coordinate as a binary value of 1 or 0. A chromaticity coordinate determination circuit A65 that performs a chromaticity coordinate determination circuit A65, and a chromaticity coordinate determination circuit B that discriminates between 1 and 0 binary values under conditions that are more relaxed than this circuit 65.
66, pattern P1 is obtained from circuit 65, and pattern Q1 is obtained from circuit 66.

On the other hand, the color separation signal R obtained by the color scanning device 63,
From G and B, the G component is used as a contrast signal, which is passed through a threshold circuit 67 which discriminates it into binary values 1 and 0 with a high threshold value A, and a threshold circuit 68 which discriminates it into binary values 1 and 0 with a low threshold value B. Pattern P2 from circuit 67, pattern Q2 from circuit 68
get.

Then, pattern P1 and pattern P2 are set to A. A pattern P is obtained by passing it through an ND gate 69, a pattern Q is obtained by passing the pattern Q1 and a pattern Q2 through an AND gate 70, and a pattern Q is obtained by passing these through a connection processing circuit 71, and only the components connected to the pattern P are extracted from the pattern Q. Final binarized output R
shall be.

60-63, 67-7 of each block in Figure 6
The parts indicated by 0 are publicly known, and the connection processing circuit 71 is realized by the parts shown by 7 to 10 in FIG. 3 or the parts shown by 46 to 49 in FIG. will be described in more detail.

In FIG. 7, an adder and analog dividers 75 and 76, which are composed of resistors 70 to 73 and an amplifier 74, represent an example of the configuration of the chromaticity coordinate calculation circuit 64 in FIG. , r=R/(R+G+B), g=G/(R+
G+B) is obtained.

In addition, comparators 77 to 80 and AND gates 81 to 80 in FIG.
83 and a reference voltage generation circuit 84 represent an example of the configuration of the chromaticity coordinate determination circuit A65 in FIG.
and AND gates 89 to 91 represent an example of the configuration of the chromaticity coordinate determination circuit B66.

Pattern P1 and pattern Q1 are obtained by this circuit, respectively.

Now, the chromaticity coordinate determination circuit A will be described for obtaining a pattern P1 included in cA and a pattern P2 included in CB in the r and g chromaticity coordinates shown in FIG.

Output e1 of reference voltage generation circuit 84 and analog divider 75
The outputs r of are compared by a comparator 77, and if the condition r>e1 is satisfied, the output r1 becomes 1.

Similarly, the output r2 of the comparator 78 becomes r2=1 when the condition r<e2 is satisfied.

Therefore, when these r1 and r2 signals are ANDed by the AND gate 81, the output r12 becomes 1 only when the condition e1<r<e2 is satisfied.

Similarly, the output g12 of the AND gate 82 is also e3<g<e4
It becomes 1 only when .

Furthermore, by passing the signals r12 and g12 through the AND gate 83, a signal is obtained where e1<r<e2 and e3<g<e4 are established, that is, when the coordinates of r and g are within CA in FIG. 8, P1 is obtained. = 1 is obtained.

In the case of the chromaticity coordinate determination circuit B66, it is exactly the same.
, g, it is possible to obtain a signal where Q1=1.

Further, by arbitrarily changing the reference voltages e1 to e3, the r and g coordinates can be arbitrarily determined.

As a result, according to the present invention, the problems of the prior art in which various colored characters are quantized in pieces or are connected but are judged as incorrect colors can be solved. This makes it possible to realize a character reading device that has high quality binarized patterns and can reliably capture color information.

As another example of application, when you want to correct and input characters that have already been written, you can draw a red line on the correction item and write the correction content with a blue writing utensil. This means that it will be easy to erase the connected parts of , and replace them with characters written with a blue writing utensil.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams for explaining color theory, Figure 3
4 and 4 are diagrams showing a conventional example, FIG. 5 is a diagram for explaining the principle of the present invention, and FIG. 6 is a block diagram showing an embodiment of the present invention. Fig. 7 is a diagram specifically showing a part of the block shown in Fig. 6, and Fig. 8 is a diagram showing the principle shown in Fig. 5 in relation to the operation of the circuit shown in Fig. 7. It is. 63...Color scanning device, 64...Chromaticity coordinate calculation circuit, 65, 66...Chromaticity coordinate determination circuit, 67, 68...Threshold value circuit ．． 69,70・
...AND gate, 71...Connection processing circuit.

Claims (1)

[Claims] 1. A means for scanning a character pattern on a record carrier to obtain a color separation signal corresponding to the color separation components of the character pattern and an electric signal corresponding to the shading, and a means for scanning the shading signal obtained by this means, including at least a noise component. a first threshold circuit for obtaining a pattern P1 which is binarized with a high threshold to ensure that no character components are included; a second threshold circuit, a means for calculating a chromaticity coordinate value of each point from the color separation signal, and a means for calculating a chromaticity coordinate value of each point from the color separation signal; A first chromaticity coordinate determination circuit for determining that the color is a predetermined color and obtaining pattern P2; a second chromaticity coordinate determination circuit for determining that the pattern is a color and obtaining a pattern Q2; a means for obtaining a logical product pattern P of the pattern P1 and the pattern P2 and a logical product pattern Q of the pattern Q1 and the pattern Q2; A character reading method comprising means for extracting connected components of points corresponding to a pattern P on a pattern Q.