JP2853160B2 - High-resolution image reading circuit - Google Patents

Description

The present invention relates to a facsimile apparatus and an image scanner,
In particular, the present invention relates to a circuit for reading an image by planar scanning using an image sensor.

2. Description of the Related Art Conventionally, this type of image reading circuit processes the output of a planar scanning image sensor as it is as image information, and the resolution of main scanning and sub-scanning is determined by the pixel size of the planar scanning image sensor.

Problems to be Solved by the Invention In the conventional image reading circuit described above, since the output of the image sensor is processed as it is, the resolution is determined by the pixel size of the image sensor. It is necessary to make the sensor pixel twice as fine or to double the optical lens magnification,
In order to read an image of the same screen size at twice the resolution, there is a disadvantage that an extremely expensive image sensor must be used.

The present invention has been made in view of the above-described conventional circumstances, and accordingly, an object of the present invention is to provide a novel image reading circuit which can solve the above-mentioned disadvantages inherent in the conventional technology and can obtain a high resolution. To provide.

To achieve the means above object for solving the problem, high-resolution image reading circuit according to the present invention, an image sensor for reading an image by a plane scanning, correction calculation of the output data x _t and the front line of the image sensor Correction calculation data y _{t for the} current line from data y _t-1
And generating an arithmetic circuit _{y t = (Ax t -y t} -1), constituted by a line memory for temporarily storing said correction calculation data.

Next, a preferred embodiment of the present invention will be specifically described with reference to the drawings.

FIGS. 3 (1) and 3 (2) are read data diagrams of the image sensor in the sub-scanning direction, and FIG. 3 (1) shows the case of reading by sub-scanning control suitable for the resolution of the image sensor. FIG. 2) shows a case where the image is read by the double-scanning sub-scanning control.

As can be seen from FIG. 3 (2), even if reading is performed by the sub-scanning control of twice the density, a reading error occurs because the previous line is read together with the current line, and the double resolution cannot be obtained. .

The present invention is a high-resolution image reading circuit for obtaining a double resolution by correcting the reading error by calculation.

FIG. 1 is a circuit block diagram showing one embodiment of the present invention.

Referring to Figure 1, the image sensor 11 outputs a signal X _t read in synchronism with the clock of the pixel clock generating circuit 17, the read signal X _t is converted into a digital signal by the A / D converter 12 is inputted as an image sensor output data x _t to the arithmetic circuit 21. On the other hand, in synchronization with the clock of the pixel clock generation circuit 17, an address signal is received from the pixel counter 16, and the operation image information yt _{-1 of} the previous line stored in the line memory 15 is also input to the operation circuit 21. In the arithmetic circuit 21, the output data x _t of the image sensor 11, a multiplier
(Usually in A is a constant 2) by A times 13 is subtracted the arithmetic image data y _t-1 of the previous line by the subtracter 14, and outputs the operation image information y _t of the current line.

The arithmetic circuit 21 is represented by _{y t = (Ax t -y t} -1), the effect of removing information content of the previous line read in conjunction with the current line in the sub-scanning control twice the density and the Have. The operation image information y _t of the current line, which is the output of the arithmetic circuit 21, and at the same time is treated as the image information after correction, is again stored in the line memory 15 for the next line processing.

FIGS. 2 (1) to 2 (5) are signal transition diagrams showing correction of read data in the sub-scanning direction according to one embodiment of the present invention.

Referring to FIGS. 2 (1) to (5), FIG. 2 (1)
, For a pixel with a read image is a sub-scanning direction of the image signal Z _t. (2), the sub-scanning control at twice the density of the resolution of the image sensor 11 is a reading sensor output data x _t. The average level of the current line and the previous line is output to the sensor because the sub-scan control is performed at twice the density of the resolution.
and read as x _t, it is impossible to obtain sufficient resolution. The original current line data of (1) is Z _t and the previous line is
When Z _t-1, the image sensor output x _t (2) x _t =
( _Zt + _Zt-1 ) / 2. (3) is a multiplier of the arithmetic circuit 21
13 represents Ax _t (where A = 2). (4)
Is the output y _t-1 line memory 15, (5) represents the output y _t of the subtractor 14. y _t is calculated by the arithmetic circuit 21 as y _t = (2x
represented by _t -y _t-1), the original image information to the Z _t and calculating image information y _t coincide.

As described above, according to the present invention, scanning is performed at a density twice as high as the resolution in the sub-scanning direction of the image sensor, and the current line is obtained from the output data _xt and the correction operation data yt _{-1 of the} previous line. the correction operation data y _t by generating by _{y t = (Ax t -y t} -1) operation circuit, corrects the read data error, it is possible to obtain the sub-scanning direction twice the resolution.

This allows you to use expensive image sensors without using
With a low-cost memory and a simple arithmetic circuit, it is possible to obtain twice the resolution of the conventional one.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention. 11: Image sensor, 12: A / D converter, 13: Multiplier, 14: Subtractor, 15: Line memory, 16: Pixel counter, 17: Pixel clock generation circuit, _Xt : Image sensor analog output, _xt ... Image sensor output data, y _t-1 ... Previous line correction calculation data, y _t ... Current line correction calculation data FIGS. 2 (1) to (5) are signal transition diagrams of one embodiment of the present invention. 1) an image signal (Z _t ) of one pixel of the read image in the sub-scanning direction; (2) an image sensor output data (x _t ) at the time of sub-scanning control at twice the resolution; (3) Is the output data of the multiplier 13 (Ax _t : A =
2) and (4) are the previous line correction calculation data (y _t-1 ),
(5) shows the current line correction calculation data (y _t ). FIGS. 3 (1) and 3 (2) are read data diagrams of the image sensor in the sub-scanning direction, and FIG. 3 (1) shows a case where reading is performed by sub-scanning control suitable for the resolution of the image sensor.
(2) shows a case where the image is read by the sub-scanning control having twice the density of the image sensor.

Claims (1)

(57) [Claims] 1. An image sensor for reading an image by planar scanning, a correction operation of a current line from output data x _t (subscript t indicates a line number) of the image sensor and correction operation data y _{t-1 of a} previous line. arithmetic circuitry y _t to generate data y _t =
A high-resolution image reading circuit comprising: (Ax _t -y _t-1 ) (A is a constant); and a line memory for temporarily storing the correction operation data.