JPH04288541A - Image distortion correction device - Google Patents

Abstract

PURPOSE:To obtain an accurate image input at all times by an optical reader regardless of the accuracy of the repetition of reading. CONSTITUTION:Image data on a document and a scale which are inputted from a plane scanner 2 which has a scale at a read part are recorded in a 1st image file 11. A corresponding point calculating means 5 calculates the coordinate values of points corresponding to the size of the document from the image data on the scale stored in the 1st image file 11 and stores them in a 2nd data file 14. The accurate coordinate values of specific points of the scale are already stored in a 1st data file 13 and a correction parameter calculating means 8 calculates a correction parameter from the coordinate values in the 1st data file 13 and 2nd data file 14. An image correcting means 9 corrects a document image stored in the 1st image file 11 by using the calculated correction parameter.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image distortion correction device for correcting distortion of an input image by an optical image input device and obtaining accurate input image data.

0002

[Prior Art] FIG. 11 is a diagram showing the process of creating a YMCK4 version with a plain mesh portion.
When creating a K4 plate, the line plate 28 is inputted using the flat scanner 2, the plain mesh data is created using the plain mesh creating device 25, the plain mesh portion and other portions are laid out using the layout system 26, and then the plain mesh data is created using the drum scanner 27. Outputs the 4th version of YMCK. Next, the YMC output from the scanner
By combining the K four-color plate and the line plate 28, a final YMCK four-color plate is completed. However, when compositing, in most cases the YMCK 4 output from the drum scanner 27
The halftone dot boundaries of the color plate and the outline of the line plate do not match, making it impossible to create a good final YMCK four-color plate. this is,
This is because if a simple plane scanner 2 is used to input line drawings, the input image will be distorted, and the plain screen creation device 25 will create halftone dots in the area surrounded by the distorted line drawings. As a distortion correction technique to solve this problem, for example,
No. 32477 entitled "Image information correction method and apparatus". In this conventional invention, first, graph paper with accurate grid spacing is prepared, and the grid spacing is entered numerically into a computer. Next, the same graph paper is input as an image through an optical camera, and the distance between the squares is calculated. Here, the distortion characteristic information of this optical system is calculated by comparing the interval between the squares through the optical system and the interval between the squares through the optical system. Thereafter, distortion correction of the input image is automatically performed based on the distortion characteristic information calculated for that optical system.

0003

[Problem to be Solved by the Invention] However, since the repeatability of the optical system is not necessarily accurate, the degree of distortion differs depending on the input image, and the conventional technology described above is unable to measure the distortion using pre-calculated distortion characteristic information. Even if correction is made, there is a problem that accurate correction cannot be made. SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide an image distortion correction device that can always obtain accurate image input regardless of the repeatability of an optical reading device.

0004

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an optical reading device having a scale in the reading section, and storing images of the original and the scale read by the optical reading device. image storage means;
A first one in which accurate coordinate values of a specific point on the scale are stored.
a data file, a corresponding point calculation means for calculating the coordinate value of a point corresponding to the specific point from the image data of the scale stored in the image storage means, and a coordinate value of the point calculated by the corresponding point calculation means. a second data file to be stored; a correction parameter calculation means for calculating a correction parameter from the data of the first data file and the second data file; An image distortion correction apparatus is used, which includes an image correction means for correcting an image of a document stored in a storage means, and a data output means for outputting image data corrected by the image correction means.

[0005]

[Operation] In the image distortion correction apparatus according to the present invention, when an original image is inputted from an optical reading device having a scale in the reading section, the image data of the inputted original and the scale are stored in the image storage means. The corresponding point calculation means calculates coordinate values of points corresponding to the size of the document from the image data of the scale stored in the image storage means, and stores the coordinate values in the second data file. In addition, the first data file stores the exact coordinate values of a specific point on the scale,
The correction parameter calculation means extracts a point corresponding to the size of the document from the first data file, and calculates a correction parameter from the coordinate value of the extracted point and the coordinate value of the second data file. The image correction means uses the calculated correction parameters to correct the image of the document stored in the image storage means.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. The image distortion correction device 1 shown in FIG. 1 includes a flat scanner 2 for image input, and an input control means 3 for controlling the input image.
, a magnetic disk 4 for storing image data, coordinate value data, etc., a corresponding point calculation means 5 for calculating a specific point corresponding to the document size, a display means 6 for displaying the corresponding point in the original size, and a display means 6 for displaying the corresponding point on the display screen. A pointing device 7 for instructing, a correction parameter calculating means 8 for calculating parameters for distortion correction, an image correcting means 9 for correcting a distorted image, and an output control means for controlling output of the corrected image to a plain screen forming device or the like. 10. Magnetic disk 4 shown in FIG.
are the first image file 11, the second image file 12,
First data file 13, second data file 14
It has four files. The first image file 11 is input by the flat scanner 2 and stores the scale and image data of the original before correction via the input control means 3. Second
The image file 12 stores image data corrected by the image correction means 9. Accurate coordinate data of a specific point on the scale is stored in advance in the first data file 13. The second data file 14 stores coordinate data of three points calculated by the corresponding point calculating means 5 and corresponding to the size of the document.

FIG. 2 is a flowchart showing the operation of the apparatus shown in FIG. Hereinafter, the operation of the image distortion correction device 1 will be explained according to this flowchart. FIG. 3 is a diagram showing a state in which the scale 16 and the original 18 are set on the original table 15 of the flat scanner 2. As shown in FIG. As shown, document table 1
A film 17 on which a scale 16 is printed is pasted on the film 5, and an original 18 is set on top of the film 17. When setting the original 18 on the original table 15 of the flat scanner 2, the original 18 is set at a position slightly apart from the scale 16. After setting the original 18, the flat scanner 2
reads the set original image and scale image. (S1)

[0008] The read original and scale images are stored in the first image file 11 via the input control means 3. (S2)

Next, a scaled image of the area specified by the size of the input document 18 is displayed from the image data stored in the first image file 11. Figure 4 shows flat scanner 2.
The relationship between the scale 16 and the original 18 on the original table 15 is shown, but the displayed area is based on the scale 16 of the input original 18.
This is a region including lattice points 19, 20, and 21 closest to the side vertices. At this time, the grid point 20 is the origin of the scale 16. Other grid points 19 and 21 are determined by the size of input document 18. Figure 5 shows the screen 2 of the display means 6 at this time.
As shown in the figure, the area 24 including this grid point is displayed in its original size on the screen of the display means 6. There are 1 grid point each in the area 24 of the displayed scale image.
Only one grid point is included, and two grid points are not displayed in the area 24 because the neighboring grid point is included. (S3)

0010
] Here, the operator specifies the grid points displayed on the screen 22 with the pointing device. As shown in FIG. 5, the coordinate values of the corresponding points are calculated by specifying with the pointing device 7 a portion 23 where two lines intersect in an area 24 displayed in the original size on the display screen. (S4)

The calculated coordinate values of the three points are stored in the second data file 14. (S5)

Next, the correction parameter calculation means 8 extracts three grid points corresponding to the size of the document from the first data file 13, and also extracts the coordinate values of the three points stored in the second data file 14. Extract.

The data format of the input image data of the apparatus according to this embodiment will now be explained. FIG. 6 is a schematic diagram showing an example of the data of this embodiment. As shown in the figure, the data read by the device according to this embodiment using the flat scanner 2 is in the form of a run length for each line in the X-axis direction. ing. In FIG. 6, the left side in parentheses represents the color number, and the right side represents the length. In the example in Figure 6, the first line “(2, 3)(
3, 14)'' indicates that the color with color number 2 continues for 3 pixels from the left, and then the color with color number 3 continues for 14 pixels. The correction parameter calculation means 8 calculates correction parameters using a correction matrix that can utilize this data format.

FIG. 7 is a diagram showing a figure distorted by various distortions of the figure. The correction matrix will be explained below using FIG. 7. Let the exact coordinates of a specific point in the first data file 13 be (Xi, Yi), the coordinates of a specific point in the second data file 14 be (xi, yi), and Pi
= (Xi, Yi, 1) Qi= (xi, y
i, 1), then using a 3×3 matrix A, Pi=Q
Since it can be written as i×A, the distortion correction matrix A is determined by giving the coordinate values of three points to each of P and Q.

FIG. 7(a) shows a figure distorted by general distortion, and the distortion correction matrix for this distortion is expressed as follows.

[0016]

[Math 1]

FIG. 7(b) shows a figure distorted due to parallel movement of the figure, FIG. 7(c) shows a figure distorted due to enlargement/reduction of the figure, and FIG. 7(d) shows a figure distorted due to the parallel movement of the figure. Figure 7(e) shows a figure distorted by Y-direction shearing, and Figure 7(f) shows a figure distorted by rotation of the figure. The correction matrix is expressed as follows.

[0018]

[Math 2]

In this case, the matrix M in the formula (2) corresponds to parallel movement, the matrix W in the formula (2) corresponds to expansion/reduction, and the matrix C in the formula (2) corresponds to expansion/reduction.
x corresponds to shear in the X direction, matrix Cy in the equation (2) corresponds to shear in the Y direction, and matrix R in the equation (2) corresponds to rotation.

Since the five types of correction matrices shown in equations (1)-(2) are linearly dependent on the general distortion correction matrix A, general distortion correction can be performed using four types of corrections except for one type. That is, it can be expressed as A=M×Cx×W×R────(7). Among the five types of correction matrices, Y-direction shear and rotation change the vector perpendicular to the line, so
Unable to convert run length data. Therefore, if angular correction and translation are ignored, distortion correction can be performed using two matrixes: the matrix W related to scaling in the X and Y directions, and the matrix Cx related to shearing in the X direction. Therefore, by substituting each element into equation (7), the following equation is obtained.

[0021]

[Math 3]

[0022] Solve this equation and obtain the following solution. θ= tan-1(d/a) ─────
──────────(8) mx=(c
e-fb)/(ae-db) my=(dc
-af)/(db-ae) wx=a/co
s θ──────────────────(9)
wy=e cosθ−b sinθ──────
──────(10) cx=(bcos2θ
+e cosθ sinθ)/a────(11)

0
In order to obtain the matrix W related to scaling in the X and Y directions, it is sufficient to obtain wx and wy of the elements, and in order to obtain the matrix Cx related to shearing in the X direction, it is sufficient to obtain cx of the elements. By extracting the coordinate values of three points each from the first data file 13 and the second data file 14, each element a, b, c, d, e, f of the correction matrix A is calculated, and a
, d is also used to calculate θ using equation (8). Therefore, according to equations (9), (10), and (11), the correction parameter w
x, wy, and cx are calculated. The above calculations are performed by the correction parameter calculation means 8 to calculate correction parameters. (
S6)

Using the correction parameters wx, wy, and cx obtained in this way, the image correction means 9
The document image stored in the image file 11 of is corrected. FIG. 8 is a diagram showing the state of the data of the apparatus shown in FIG. 6 after correction. FIG. 8(a) is a diagram showing the state after correction when wx=2. As shown in the figure, when the value of the correction parameter wx is 2, the length of each run of the image data shown in FIG. is doubled and expanded in the X direction to create image data. Specifically, the first line data “(2, 3)
(3, 14)” becomes “(2, 6) (3, 28)”. FIG. 8(b) is a diagram showing the state after correction when wy=2. As shown in the figure, when the value of the correction parameter wy is 2, two lines with the same run data are written consecutively. , image data enlarged in the Y direction is created. Specifically, the data on the first line is written as “(2, 3)(
3, 14)", and the data on the second line is also "(2, 3)".
)(3,14)”. The data on the third line is the same as the data on the second line before correction (0, 6) (1, 4) (
0, 7)", and the data on the 4th line is also "(0, 6)".
(1, 4) (0, 7)”. (c) in Figure 8 is c
9 is a diagram showing the state after correction when x=1, and FIG. 9 is a diagram showing the relationship between the correction parameter cx and the shearing of the figure in the X direction. Since the correction parameter cx is cx=tanα for the inclination angle α shown in FIG. 9, the shear strain in the X direction is corrected by translating the L-th line data by L×cx. When the value of the correction parameter cx is 1, as shown in Figure 8(c), the first line is 1, 2
Move the first line two places and the third line three places to the left. Fill in the empty space with the appropriate color depending on the situation. Specifically, the first line data “(2, 3) (3, 14)
” becomes “(2, 2) (3, 14) (99, 1)”. As described above, the image correction means 9 performs distortion correction processing. (S7)

The correct original image corrected by the image correction means 9 is stored in the second image file 12. (S8)

0
[026] The accurate original image obtained in the above manner is outputted to the plain mesh forming device 25 via the output control means 10. The plain mesh creating device 25 colors areas divided by the outline of the original image on the display, determines the Y, M, C, and K halftone percentages of each area, and creates plain mesh data. Next, the created plain mesh data is laid out in the layout system 26 along with other data such as image data other than line drawings. Then, based on the allocated data, the drum scanner 27 outputs a YMCK four-color plate. By combining the YMCK four-color plate output from the drum scanner 27 and the line plate 28, the final Y
A four-color plate of MCK is obtained.

In the above embodiment, a specific point on the scale image read by the flat scanner 2 along with the original 18 was directly designated and inputted using the pointing device 7, but this method uses the fact that the data of this device is in a run-length format. Alternatively, specific points on the scale image may be automatically recognized and input. The automatic recognition of a specific point on a scale image will be described below. FIG. 10 is a diagram showing data in the area 24 shown in FIG. 5, in which color number 0 represents white and color number 1 represents black. When the data in this area 24 is scanned line by line from above, there is a white part of about 4 to 7 pixels on the left and right between several lines in the upper part of the area 24, and a black part of 2 to 3 pixels in the center. Detects that there is. As scanning continues, a line is detected in which all 14 pixels are black and there are no white areas. As the scanning continues, several lines are again detected that have white parts of about 4 to 7 pixels on the left and right, and a black part of 2 or 3 pixels in the center. Based on this detected data, 2
Find the equation of the straight line and calculate the coordinates of the intersection. In this way, the area 24 including the specific point of the scale image
Automatically recognizes the intersection of two straight lines running inside.

[0028]

As described above, according to the present invention, the image data of the original and the scale input from the optical reading device having the scale in the reading section are stored in the image storage means, and the corresponding point calculation means is stored in the image storage means. The coordinate values of a point corresponding to the size of the document are calculated from the stored scale image data and stored in a second data file, and the correction parameter calculation means calculates the coordinate values of a point corresponding to the size of the document from the stored image data of the scale, and the correction parameter calculation means calculates the coordinate values of a point corresponding to the size of the document from the stored image data of the scale. A point corresponding to the size of the document is extracted from the first data file, a correction parameter is calculated from the coordinate value of the extracted point and the coordinate value of the second data file, and the image correction means uses the calculated correction parameter to create an image. Since distortion correction is performed using an image distortion correction device that corrects the image of the document stored in the storage means, accurate input data can always be obtained regardless of the repeat accuracy of the optical reading device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an image distortion correction device 1 according to the present invention.

FIG. 2 is a flowchart showing the operation of the image distortion correction device 1.

3 is a plan view of the flat scanner 2 shown in FIG. 1, with a scale 16 and a document 18 set on the document table 15; FIG.

FIG. 4 is an explanatory diagram showing the positional relationship between the original 18 and the scale 16.

FIG. 5 is a schematic diagram showing a state in which an area including grid points is displayed in its original size on the screen of the display device 6.

FIG. 6 is a schematic diagram showing the data structure of the image distortion correction device 1 according to the present invention.

7 is a schematic diagram showing a figure distorted by the flat scanner 2. FIG.

8 is a schematic diagram showing data corrected by the image correction means 9. FIG.

FIG. 9 is a schematic diagram showing the relationship between shear in the X direction and inclination angle α.

10 is a schematic diagram showing a data structure within the area 24 shown in FIG. 5. FIG.

FIG. 11 is a block diagram showing the process of creating a YMCK4 version for printing.

[Explanation of symbols]

1 Image distortion correction device 2　Flat scanner 3 Input control means 4 Magnetic disk 5 Corresponding point calculation means 6 Display means 7 Pointing device 8 Correction parameter calculation means 9 Image correction means 10 Output control means 11 First image file 12 Second image file 13 First data file 14 Second data file 15　Manuscript stand 16 scale 17 Film 18 Manuscript 19 Lattice points 20 Origin of scale 21 Lattice points 22 Screen of display device 6 23 Lattice points 24 Original size display area 25　Plain net making device 26 Layout system 27 Drum scanner 28 Line version

Claims (3)

[Claims] 1. An optical reading device having a scale in a reading section; an image storage means for storing an image of a document and a scale read by the optical reading device; a stored first data file and a corresponding point calculation means for calculating coordinate values of a point corresponding to the specific point from the image data of the scale stored in the image storage means; a second data file storing coordinate values of the points;
a correction parameter calculation means for calculating correction parameters from data in the first data file and the second data file; and an image of the document stored in the image storage means based on the parameters calculated by the correction parameter calculation means. An image distortion correction device comprising: an image correction means for correcting image data; and a data output means for outputting image data corrected by the image correction means. 2. Display means for displaying an image of the scale in which the corresponding point calculation means is stored in the image storage means;
2. The image distortion correction apparatus according to claim 1, further comprising a pointing device for indicating a grid point on the scale image displayed on the display means. 3. The corresponding point calculation means automatically calculates coordinate values of grid points of an image of a scale within a region specified by the size of the document stored in the image storage means. The image distortion correction device according to claim 1.