JPS62195981A - Picture reader - Google Patents

Abstract

PURPOSE:To prevent the cutting of fine lines or the collapse of a picture by providing a comparator for discriminating a picture signal as three values of a black and a white and an intermediate levels, a memory for three lines and a decision circuit for deciding the picture element level of four points and converting an intermediate picture element level into the binarization level of the black and the white and outputting. CONSTITUTION:The picture signal from an image sensor 1 is amplified by an amplifier 2 and converted into the three values of the black, the white and the intermediate level. The output of a comparison voltage generator 3 is divided by resistances R1, R2 to generate a threshold voltage U and a threshold voltage L. The outputs b2, b1 of the comparison circuit 4 go to (1, 1) in the case of the black level and (0, 0) in the case of the white level and (0, 1) in the case of the intermediate level of the black and the white. The three valued levels are sequentially inputted to the shift memory 5 of the tree lines. The picture element level information of the four points adjacent to the scanning output picture elements b2, b1 (i, j) is inputted to the decision circuit 6 and converted into the black or the white level and outputted according to the contents thereof, when the output picture elements b2, b1 (i, j) are the intermediate levels (0, 1). Thereby, the cutting in the fine lines of a character or the collapse of the character are prevented to obtain the character picture of good quality.

Description

[Detailed Description of the Invention] Field of Use in Childcare The present invention scans an original image using an image sensor or the like,
The present invention relates to an image reading device that converts into a black and white binary electrical signal.

2. Description of the Related Art In recent years, image reading devices have been widely used as input devices for image signals into personal computers, food processors, and the like. In particular, a device that scans and reads an image using an image sensor such as a COD and converts it into a black and white binary digital pixel signal is generally well known.

Hereinafter, one row of the above-mentioned conventional image reading devices will be explained with reference to the drawings.

FIG. 8 shows a schematic configuration diagram of a conventional image reading device. In FIG. 8, 14 is an image original, 15 is a fluorescent lamp, 16 is a focusing fiber lens, and 17 is an image sensor. Further, FIG. 9 shows a schematic configuration diagram of an electric circuit of a conventional image reading device, in which 18 is an image sensor;
19 is an amplifier, 20 is a comparison circuit, and 21 is a comparison voltage generator.

The operation of the image reading device configured as described above will be described below.

First, an image on a document 14 illuminated by a fluorescent lamp 15 is focused onto an image sensor 17 by a focusing fiber lens 16 . The image formed on the image sensor 17 is sequentially scanned and converted into an electrical signal with a level corresponding to the intensity of light. Additionally, a fluorescent lamp 15° focusing fiber lens 16. An optical system composed of an image sensor 17 reads the image of the original by moving along the original 14. The reading direction of the image sensor 17 is called a main scanning direction, and the moving direction of the optical system is called a sub-scanning direction. In FIG. 9, an image signal converted into an electric signal by an image sensor 18 is amplified by an amplifier 19, and converted into a black and white binary signal by a comparison circuit that discriminates black and white. A comparison voltage generator 21 generates a threshold voltage for determining whether the scanned image signal is white or black. Since the image sensor 17 is divided into each pixel, the output from the comparator circuit 20 is a black and white 2 signal corresponding to each pixel.
A pixel signal of value is obtained.

Problems to be Solved by the Invention However, the above configuration has the disadvantage that the quality of the read image deteriorates.

FIG. 10 is a diagram illustrating a state in which each pixel is converted into a black and white binary signal in a conventional image reading device. In Fig. 1o, ral is the state of image scanning by the image sensor, (b) is the output signal of the image sensor, (
C) and (d) are diagrams showing the state of black-and-white binary conversion. As shown in Figure 10(a), the line width of the black line image is narrow;
Furthermore, if the image sensor's reading pixel is located in the middle of the black line boundary, the button cannot be sufficiently detected as shown in the sensor's output signal. If the black and white discrimination voltage is set high as threshold A, the image becomes blurred, thin lines become white, and the lines are cut off. On the other hand, if the threshold value B is set low, there are problems in that the lines become thicker, the white parts are crushed, and the lines become connected.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an image reading device that prevents the occurrence of thin line breaks and image collapse due to thickening.

Means for Solving the Problems In order to solve the above problems, the image reading device of the present invention includes:
A comparison circuit that discriminates the image signal of the image sensor into three values of white, black, and monochrome intermediate level, a memory for three lines for storing the three-value levels, and a pixel level of at least four points adjacent to the scan output pixel. It is equipped with a circuit for determining the content.

According to the above-described configuration, when the pixel currently being scanned and output is at an intermediate level between black and white, the output pixel level is set to white or By converting to the black level and outputting it, it is possible to eliminate the breakage of thin lines and thickening of the image.

Embodiment Hereinafter, an image reading apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration diagram of an image reading device according to an embodiment of the present invention. 1st
In the figure, 1 is an image sensor, 2 is an amplifier, 3 is a comparison voltage generator, 4 is a comparison circuit, 5 is a shift memory for three lines, 6 is a determination circuit, and 7 is an output circuit.

The operation of the image reading apparatus configured as described above will be described below with reference to FIG.

The image signal from the image sensor 1 is amplified by an amplifier 2, and converted by a comparator circuit 4 into three values: white, black, and a monochrome intermediate level. The output of the comparison voltage generator 3 is divided by resistors R1 and R2 to generate threshold voltages Ff and U.

Output b2 of comparison circuit 4. b1 is the black level (1, 1
), and (0,0) at the white level.

At the black and white intermediate level, it is (0, 1). These three-value levels are sequentially input to the shift memory 5 for three scanning lines. The shift memory 5 has a capacity of 2 bits per pixel and 3 main scanning lines, and each pixel is shifted in sequence. This shift memory 5 allows scanning output pixel b2b1(i
, j), each pixel level b2b1(x+1.1
), b2b1(t, 1 1).

b b (i, j+1), b2b1 (i-1, j)
The information is input to the determination path 6, and depending on the content, when the output pixel b2b1 (i, i) is at the intermediate level (o, 1), it is converted to black or white level and output.

FIG. 2 is a diagram showing the positions of adjacent pixels in the main scanning direction and the sub-scanning direction.

FIG. 3 is a diagram showing a black-and-white conversion state of the read signal of the image reading device in FIG. 1. FIG. 3(b) is a diagram showing the output signal of the image sensor 1, and the output (b) of the comparator circuit 4.
2. bl ) is greater than the threshold voltage U (1,1),
When lower than L threshold voltage (0, 0 input) When in between (0,
1). FIG. 3(C) shows the state of the pixel level of the output of the comparator circuit 4 including the intermediate level. FIG. 3(d) is a diagram showing a state in which the intermediate level is converted to a white or black level depending on the content of the adjacent pixel level.

FIGS. 4 and 5 are diagrams for explaining this conversion method. In Figure 4, the pixel (i, j) currently being scanned is at the black and white intermediate level (0, 1), and the pixel (i, j-1) adjacent to the main scanning direction is at the white level (0, 0). When the adjacent pixel (i, j+1) on the opposite side is at the intermediate level (0, 1), the output pixel (i, j) is converted to the black level (,). FIG. 4(b) is an example of a case in which they are adjacent in the sub-scanning direction.

FIG. 5 shows an embodiment of a determination circuit for performing this conversion. 1o is a configuration example of a determination circuit,
The output of the judgment circuit is bl(t,+)・b2(i,+)・(bl(1,] −
1) When the logical expression of bl(i, J+1) and b2(i, j+1) becomes true, the output is converted to black level. 11
is an output circuit consisting of an OR circuit, and it is the OR of the output of b2 (i, j) and the output of the judgment circuit 10, so if there is no judgment output, the white and black levels are the same, and the intermediate level is converted to white level. On the other hand, if the determination output is true, the intermediate level is converted to black. The output circuit 11 can also add the conditions of other determination circuits by ORing, and generates an image output converted into black and white binary pixels.

In the above explanation, the conditions for the determination circuit 1Q are that with adjacent pixel information b(i, j-1) and b(i, j+1), b
Although (i, j-1) is white and b(i, j+1) is an intermediate level, the conditions may be reversed. However, if only one of the conditions is not used, b(ilj+1) will also be converted to the black level, making the thin line thicker. Therefore, the fifth
In the figure, only the conditions under which b(i, j-1) is white are used.

The same applies to the sub-scanning direction (FIG. 4(b)). FIG. 3(d) is a diagram showing a pixel output signal converted into a black and white binary level under the above conditions.

As described above, according to this embodiment, a comparison circuit that discriminates the image signal of the image sensor into three pixel levels and a memory for three lines are provided, and the contents of the pixel level of four points adjacent to the scan output pixel are provided. By determining this and converting intermediate level pixels to white or black and outputting the result, it is possible to eliminate image distortion due to m-line breaks and image thickening. This is especially effective when reading a character image as an image, eliminating the breakage of thin lines and blurring of characters, and making it possible to obtain high-quality character images.

FIGS. 6 and 7 are diagrams showing an example of reading a thin line smaller than one pixel. In Figure 6, when the pixel being output is at an intermediate level between black and white, and both pixels adjacent to it in the main scanning direction or sub-scanning direction are both at white level, the intermediate level pixel being output is converted to black. It is configured to output. FIG. 7 shows an embodiment of a circuit that realizes the above conditions. 12 is a judgment circuit, and 13 is an output circuit, which can also be ORed with other judgment conditions. When the logical expression as a condition of the determination circuit 12 is true, the output of the determination circuit 12 is turned on and the intermediate level is converted to the black level. As a result, thin lines smaller than one pixel are reproduced in black, and line breakage can be prevented.

Effects of the Invention As described above, the present invention includes a comparison circuit that discriminates an image signal from an image sensor into three values of white, black, and intermediate level;
A line of memory and a judgment circuit that judges the pixel level information of four points adjacent to the pixel being scanned and output are provided, and depending on the result of the judgment circuit, the intermediate pixel level being output is converted to a binary level of white or black. By outputting the scanned image, it is possible to prevent the image from being distorted due to breakage of thin lines or thickening of the black line, and to obtain a high-quality read image.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an image reading device according to an embodiment of the present invention, FIG. 2 is a relationship diagram showing the reading scanning direction and pixel position, and FIG. 3 is an explanatory diagram of the operation of the image reading device of the present invention. Fourth
6 and 6 are diagrams showing the states of adjacent pixels of the image reading device of the present invention, and FIGS. 6 and 7 are circuit diagrams showing each embodiment of the determination circuit for the states shown in FIGS. 4 and 6. , FIG. 8 is a schematic configuration diagram of a conventional image reading device, FIG. 9 is a schematic circuit configuration diagram thereof, and FIG. 10 is an explanatory diagram of the operation of FIG. 9. 1...-image center, 2... amplifier, 3
...Comparison voltage generator, 4...Comparison circuit, 5...
・Shift memory, 6... Judgment circuit, 7... Output circuit, 14... Document, 16... Fluorescent light,
16...Focusing fiber lens, 17...
image sensor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
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Claims (3)

[Claims] (1) An image sensor that scans and reads an image, a comparison circuit that discriminates the image signal output from the image sensor as three values of white, black, and a monochrome intermediate level, and three lines that store the three-value levels. a determination circuit that determines the content of the pixel level of at least four points adjacent to the pixel currently being scanned in the main scanning direction and the sub-scanning direction, and the An image reading device comprising: an output circuit that converts the level of the pixel currently being output to a white level or a black level when the pixel currently being scanned and output is at an intermediate level between black and white. (2) When the output circuit converts the level of the pixel currently being output to the black level when the levels of adjacent pixels in the main scanning direction or the sub-scanning direction are both white level and the pixel currently being scanned and output is at a black and white intermediate level. The image reading device according to claim 1, wherein the image reading device outputs the image as follows. (3) When the level of the pixels adjacent in the main scanning direction or the sub-scanning direction is one of the white level and the other is the black-and-white intermediate level, and the pixel currently being scanned and output is the black-and-white intermediate level, the output circuit 2. The image reading device according to claim 1, wherein the image reading device converts the pixel level of the pixel into a black level and outputs the black level.