JPH0937033A - Obliqueness corrector for read pixel data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the obliqueness correction of pixel data even when an object to be read is obliquely installed. SOLUTION: When a CCD line image sensor obliquely reads the object to be read and the picture element of the next line is read from an (n/2+1)th picture element, the pixel data of a k-th line become data from C1 to C(n/2) and from D(n/2+1) to Dn, the pixel data of a (k+1)th line become data from Di to D(2/n) and from E(n/2+1) to En, and the pixel data of a (k+2)th line become data from E1 to E(n/2) and from F(n/2+1) to Fn. When attention is payed upon the pixel data of the (k+1)th line, a control part performs control so that the pixel data from D1 to D(n/2) can be stored in an address (k) of a memory buffer and the pixel data from E(n/2+1) to En can be stored in an address k+1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skew correction device for read pixel data, and particularly to a CCD (Charge Coupled Device) for reading an object moving at a high speed.
e) The present invention relates to a diagonal correction method for pixel data read using a line image sensor.

[0002]

2. Description of the Related Art Conventionally, a high-speed moving object to be read is CC
In an apparatus for measuring black density or white density using a D line image sensor, for example, an ink density measuring device of a rotary press, an image of an object to be read is divided into minute pixels by a CCD line image sensor, and each pixel is divided into The black density or the white density of is converted into an electric signal, and the electric signal is subjected to data processing.

In this case, when an object to be read moving in the sub-scanning direction is scanned by the CCD line image sensor in the main scanning direction to read pixel data from the object to be read, while the CCD line image sensor scans in the main scanning direction. Also, since the object to be read moves in the sub-scanning direction, the CCD line image sensor consequently scans the object to be read obliquely.

In order to solve the above problems, CC
There is a method in which a plurality of image pickup devices forming the D-line image sensor are divided into some, and the divided image pickup device groups are arranged so as to be displaced in the sub-scanning direction, and a reading deviation occurring in each of the image pickup device groups is corrected.

In this case, the CCD on the first row and the CCD on the second row are scanned by allowing the CCD on the first row and the CCD on the second row to scan with a time Δt according to the movement of the object to be read. The reading timings in are synchronized with each other so that there is no deviation in reading.

Here, even if the moving direction of the object to be read is reversed, the object to be read can be dealt with by scanning the object to be read first by the CCD in the second row. This technique is disclosed in JP-A-1-143560.

[0007]

In the conventional skew correction method described above, since the pixel position to be read is physically fixed, the skew correction of pixel data is possible.
Since it is impossible to always attach D perpendicularly to the sub-scanning direction, when the object to be read is obliquely installed, the diagonal correction of the pixel data cannot be performed.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide an oblique correction device for read pixel data which can correct the pixel data of the read object even if the read object is installed obliquely. Especially.

[0009]

In a skew correction device for read pixel data according to the present invention, a plurality of image pickup devices are arranged in a direction orthogonal to a carrying direction of a read object, and the plurality of image pickup devices carry the carry image. A diagonal correction device for diagonally correcting read pixel data from a line image sensor for reading pixel data in a direction orthogonal to the direction, the memory buffer storing pixel data of the plurality of image pickup devices for each row address. A determining unit that determines whether or not the pixel data from the line image sensor is pixel data from an image pickup device at a preset position among the plurality of image pickup devices; And an updating means for updating the row address of the memory buffer for accumulating the pixel data when it is determined to be the pixel data.

In another skew correction apparatus for read pixel data according to the present invention, 2n (n is a positive integer) image pickup devices are arranged in the direction orthogonal to the conveying direction of the read object, and the 2n number of said image pickup devices are arranged. A diagonal correction device that performs diagonal correction of read pixel data from a line image sensor that reads 2n pixel data in a direction orthogonal to the transport direction by the image pickup element, and is provided for each of the plurality of image pickup elements for each row address. A memory buffer for accumulating the pixel data of the line image, a determination unit for determining whether or not the pixel data from the line image sensor is pixel data from the (n + 1) th image pickup device of the 2n image pickup devices, Update for updating the row address of the memory buffer that stores the (n + 1) th pixel data when the means determines that the pixel data is from the (n + 1) th image sensor And a stage.

[0011]

First, the operation of the present invention will be described below.

Pixel data from the CCD line image sensor is set in a predetermined position (n
/ 2 + 1) When the pixel data from the CCD is determined, the address for accumulating the pixel data is set to C after the predetermined position.
The address for accumulating the pixel data previously read by the CD and the address for accumulating the pixel data currently read by the CCD up to the position preceding the predetermined position are updated to be the same. As a result, even if the object to be read is installed at an angle, the pixel data can be obliquely corrected.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, an image reading apparatus according to an embodiment of the present invention includes a control unit 1, a buffer memory 2, and a driver 3.
, Pulse motor 4, CCD line image sensor 6
And an image reading unit 5 including a fluorescent lamp 7 and a platen glass 8.

When the object 9 to be read is placed on the upper surface of the platen glass 8, the pulse motor 4 is driven via the driver 3 by the control of the control unit 1 in response to an external instruction, and the fluorescence of the reading unit 5 is driven. Irradiation light is emitted from the lamp 7 to the object 9 to be read through the platen glass 8.

At this time, the CCD line image sensor 6
Moves at a constant speed in the direction of arrow S by the pulse motor 4 and reads the amount of reflected light of the read object 9 with respect to the irradiation light from the fluorescent lamp 7 for each pixel. The control unit 1 accumulates the reflected light amount read by the CCD line image sensor 6 in the buffer memory 2 for each pixel.

In the storage of each pixel in the buffer memory 2, the control unit 1 stores the pixel data previously read by the image pickup device (CCD) after a predetermined position in the CCD line image sensor 6 and the CCD line image sensor 6. The pixel data read by the image pickup device up to the previous stage of the predetermined position is stored at the same address.

FIG. 2 is a diagram showing the arrangement of the CCD line image sensor 6 of FIG. 1, and FIG. 3 is a diagram showing the scanning operation of the object 9 to be read by the CCD line image sensor 6 of FIG.

In these figures, the CCD line image sensor 6 is constituted by arranging n CCDs in a direction (direction of arrow T) orthogonal to the moving direction (direction of arrow S), and n CCDs are a. To b, that is, in the direction of arrow T (see FIG. 2).

However, while the CCD line image sensor 6 is scanning in the direction of the arrow T, the CCD line image sensor 6 is still moving in the moving direction.
Actually, n CCDs scan from A to B (see FIG. 3).

The oblique displacement generated between A and B is D
If pixels are used, 1+ is required to scan the entire surface of the object 9 to be read.
CCDs with integer rows of D or more are required. In this example, D is one pixel, and two lines of CCD line image sensors 6 are arranged. In that case, the value of D may be appropriately set when the object to be read 9 is arranged non-parallel to the main scanning direction.

FIG. 4 is a flow chart showing the operation of one embodiment of the present invention, and FIG. 5 is a diagram for explaining the diagonal correction operation of pixel data according to one embodiment of the present invention. FIG.
FIG. 5A shows pixel data read by the CCD line image sensor 6, and FIG. 5B shows pixel data accumulated in the memory buffer 2.

A skew correction operation of pixel data according to an embodiment of the present invention will be described with reference to FIGS.
However, in order to simplify the explanation, it is assumed that the CCD line image sensor 6 is arranged in one row.

The control unit 1 sets a shift amount (shift pixel number) in the sub-scanning direction when the object 9 to be read is obliquely scanned (step S1 in FIG. 4). The number of pixels displaced in the sub-scanning direction can be easily calculated if it is considered that the rotation speed of the pulse motor 4, that is, the moving speed of the object 9 to be read is constant.

Further, by checking the left and right ends of the object 9 to be read, it is possible to detect how much the object 9 to be read is installed obliquely with respect to the sub-scanning direction, and to add it to the number of misaligned pixels. The deviation pixel number D can be set accurately.

When the deviation pixel number D is set, the control unit 1 sets 1
CCD in line CCD line image sensor 6
The memory buffer 2 having a storage area for the number of pixels corresponding to the number of is secured for D + 1 rows. Here, the l-th line (1 ≤ l
A line number of memory line [l] is given to the memory buffer 2 of ≦ D + 1).

The CCD line installed in the CCD line image sensor 6 is L line. If the CCD is installed for D + 1 rows, its control is easy, but one row of C
If the CD is also read at a plurality of locations at the same time, the entire surface of the read object 9 can be read. The CCD line image sensor 6 has n pixels per row, that is, one CC.
If one pixel is read by D, n CCDs are incorporated.

When the control section 1 secures an area for accumulating the read pixel data in the memory buffer 2, the row number l of the CCD from which reading is to be started is set to "1" and the column number (pixel number) r is set to "1". , And then the fluorescent lamp 7 is turned on to activate the pulse motor 4 (step S2 in FIG. 4).

The control unit 1 reads the pixels of the object 9 to be read by the CCD one by one (step S3 in FIG. 4). In reading this pixel data, the row number l of the CCD is sequentially increased from 1 to L, and the pixel number r is sequentially increased from 1 to n for each row number l. However, the line number l returns to 1 when it exceeds L, and the pixel number r returns to 1 when it exceeds n.

The control unit 1 determines whether the reading of the pixels of the object 9 to be read by the CCD has reached a predetermined position (here, n / 2) (step S4 in FIG. 4), and the predetermined position has been reached. If not, the read pixel data is stored in the memory buffer 2 (step S5 in FIG. 4).

If the control unit 1 has reached the predetermined position, it updates the address of the memory buffer 2 and stores the pixel data read at that address in the memory buffer 2 (step S6 in FIG. 4).

For example, as shown in FIG. 5A, a CCD
In the case where the line image sensor 6 obliquely reads the object 9 to be read and the reading amount of the pixels in the next row from the n / 2 + 1th pixel becomes large, that is, the pixel data C1 to C in the kth row. (n / 2), D (n / 2 + 1) to Dn are the k + th
Pixel data D1 to D (n / 2), E (n / 2 + 1) to En in the first row
In the k + 2th row, pixel data E1 to E (n / 2), F (n / 2)
When reading +1) to Fn respectively, the control unit 1 accumulates pixel data in the memory buffer 2 as follows [see FIG. 5 (a)].

That is, the control unit 1 stores the pixel data C1 to C (n / 2) read in the k-th row at the address k-1 of the memory buffer 2, and the CCD column number is n / 2.
When the column number becomes n / 2 + 1, the address of the memory buffer 2 is updated to the address k, and the pixel data D
(n / 2 + 1) to Dn are stored in the memory buffer 2 at address k.

Similarly, the control unit 1 accumulates the pixel data D1 to D (n / 2) read in the (k + 1) th row at the address k of the memory buffer 2, and when the column number of the CCD exceeds n / 2. That is, when the column number becomes n / 2 + 1, the address of the memory buffer 2 is updated to the address k + 1, and the pixel data E (n / 2
+1) to En are stored in the memory buffer 2 at the address k + 1.

Further, the control unit 1 accumulates the pixel data E1 to E (n / 2) read in the k + 2th row at the address k + 1 of the memory buffer 2, and when the column number of the CCD exceeds n / 2, That is, when the column number becomes n / 2 + 1, the address of the memory buffer 2 is updated to the address k + 2, and the pixel data F
(n / 2 + 1) to Fn are stored in the memory buffer 2 at address k + 2 [see FIG. 5 (b)].

Therefore, the pixel data D1 to Dn are stored in the address k of the memory buffer 2, and the pixel data E1 to En are stored in the address k + 1, respectively. The read pixel data is diagonally corrected and stored in the memory buffer 2.

The control section 1 repeatedly executes the above-described steps S3 to S6 until it reads all the pixel data from the object 9 to be read, and determines that all the pixel data has been read from the object 9 to be read (FIG. 4). In step S7), the process ends.

As described above, when the pixel data from the CCD line image sensor 6 is determined to be the pixel data from the CCD at the predetermined position (n / 2 + 1) among the plurality of CCDs, the address for storing the pixel data is determined. Is updated so that the addresses at which the CCDs after the predetermined position store the pixel data previously read and the addresses at which the CCD up to the predetermined position stores the pixel data read this time become the same. Even when the read object 9 is installed diagonally, the diagonal correction of the pixel data can be performed.

[0038]

As described above, according to the present invention, a plurality of image pickup devices are arranged in a direction orthogonal to the carrying direction of the object to be read, and the plurality of image pickup devices are orthogonal to the carrying direction. In a diagonal correction device that performs diagonal correction of read pixel data from a line image sensor that reads pixel data in a predetermined direction, pixel data from the line image sensor is a pixel from an image sensor at a predetermined position among a plurality of image sensors. The row address that stores the pixel data when it is determined to be data is the row address that stores the pixel data previously read by the image sensor after the predetermined position and the pixel data that the image sensor read up to the position before the predetermined position this time. By updating so that the row address to be stored is the same, even if the object to be read is installed diagonally, the diagonal There is an effect that it is possible to carry out a positive.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of the CCD line image sensor of FIG.

3 is a diagram showing a scanning operation of an object to be read by the CCD line image sensor of FIG.

FIG. 4 is a flowchart showing the operation of the embodiment of the present invention.

5A is a diagram showing pixel data read by the CCD line image sensor of FIG. 1, and FIG. 5B is a diagram showing pixel data accumulated in the memory buffer of FIG.

[Explanation of symbols]

 1 Control Unit 2 Buffer Memory 5 Reading Unit 6 CCD Line Image Sensor 7 Fluorescent Lamp 9 Object to be Read

Claims (4)

[Claims] 1. A line image sensor in which a plurality of image pickup devices are arranged in a direction orthogonal to a carrying direction of a reading target, and pixel data is read by the plurality of image pickup devices in a direction orthogonal to the carrying direction. A diagonal correction device for performing diagonal correction of read pixel data, the memory buffer storing pixel data for the plurality of image pickup elements for each row address, and the pixel data from the line image sensor for the plurality of image pickups. Determination means for determining whether or not the pixel data is from the image pickup element at a preset position among the elements, and the memory buffer for accumulating the pixel data when the determination means determines that the pixel data is from the image pickup element An oblique correction device, comprising: an updating unit that updates a row address. 2. The update means stores a row address where pixel data read last time by the image sensor after the predetermined position and a row address where pixel data read up to this time before the predetermined position of the image sensor accumulates pixel data. The skew correction device according to claim 1, wherein the address and the address are the same. 3. A 2n (n is a positive integer) image pickup device is arranged in a direction orthogonal to the transport direction of the reading target, and the 2n image pickup devices are orthogonal to the transport direction. A diagonal correction device for diagonally correcting read pixel data from a line image sensor for reading 2n pixel data in a line, the memory buffer storing pixel data for the plurality of image pickup elements for each row address, and the line. Determination means for determining whether or not the pixel data from the image sensor is pixel data from the (n + 1) th image pickup element of the 2n number of image pickup elements; and the determination means, pixels from the (n + 1) th image pickup element An oblique correction device, comprising: an updating unit that updates a row address of the memory buffer that stores the (n + 1) th pixel data when it is determined to be data. 4. The updating means stores a row address for accumulating pixel data read last time by the n + 1th image sensor and a row address for accumulating pixel data currently read by the nth image sensor. The diagonal correction device according to claim 3, wherein the diagonal correction devices are configured to be the same.