JPS622778A - Picture processing method in digital copying machine - Google Patents

Abstract

PURPOSE:To eliminate the need to pay attention to an original setting action by detecting the coordinates of a point on a straight line connecting a corner point of the original closest to a reference side and another corner point for calculation of the sloping angle of the original and performing revolving conversion based on the sloping angle. CONSTITUTION:Data less than a certain threshold level S is detected among the read data and the coordinates (X1, Y1) of a corner point (a) closest to a reference side 9a of a size indicating frame 9 are detected for an original 8. Then the coordinates (X2, Y2) of a point (c) on a straight line connecting the point (a) and another corner point (c) of the original where the Y coordinate value is reduced at and after the point (a) are detected. Thus an arc tangent is obtained for the tilt (k) of a straight line (ab) for calculation of the angle alphabetween the line (ab) and a standard side 9b. Based on this angle alpha, the revolving angle beta is obtained to convert rotatively the read data into the data group parallel to the side 9a. Then all data on the original 8 are shifted to the coordinates which are turned by the angle beta around the corner point (X1, Y1).

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an image processing method in a digital copying machine, facsimile machine, etc., which digitally processes an original image.

BACKGROUND ART Conventionally, in a typical analog copying machine, when the transfer paper is larger than the original, a white original pressure plate is used to prevent the outside of the original from being copied in black. On the other hand, in digital copying machines, rather than making the document pressure plate white, it has a mirror surface.

Light from outside the original does not enter the light receiving section, so that the light is the same as the black image area. This is to leverage the benefits of digital processing, such as detecting the edge of the document, determining its size and position, and moving the document even if it is not in the specified position on the contact glass. .

Such functions include 1, for example, the document position/size detection function in the Canon laser copying system NP-9030;
This is known as an automatic paper selection function. but.

In such a process, the outside of the original is considered black, so unless the edge of the original is accurately detected, the copy will have a black frame outside the original.

In this regard, with the above-mentioned product, the white dot on the document is marked with an X.

The minimum and maximum values of the Y coordinate are detected, and all image data outside these values is inverted to white. However, with such a method, processing can only be performed after all images of the document have been read. Therefore, for example, when the original 1 is set diagonally on the contact glass 2 as shown in FIG. 5(a),
In order to select and copy the copy paper 4 of the rectangle 3 circumscribing this diagonal gfi[L, the obtained copy paper 4 has a black frame copy part 6 outside the original image 5 as shown in FIG. It happens. As a result, copy quality deteriorates. Therefore, in order to prevent black border copying from occurring, the operator is required to be very careful when setting the original, resulting in poor copying efficiency.

Purpose The present invention was made in view of the above points, and even when the original is set diagonally on the original table, the original image reading data is converted to the original size parallel to the original size indication frame. An object of the present invention is to provide an image processing method for a digital copying machine, etc., which can be output as data and has good workability for copying and the like.

Structure In order to achieve the above-mentioned object, the present invention uses a digital copying machine or the like that sequentially reads images of a document set on a document table equipped with an 11M size indication frame using a light receiving section. The coordinates of the corner point of the document closest to the reference side of the indication frame are detected from the read data, and the coordinates of the point on the straight line connecting this corner point of the document as the starting point with other corner points are detected from the read data. From the coordinates of these points, calculate the inclination angle of this original with respect to the original size indication frame, and based on this inclination angle, rotate and convert all the read data into a data group with coordinates parallel to the original size indication frame and output it. This is a characteristic feature.

Hereinafter, one embodiment of the present invention will be described based on the drawings. First, a contact glass 7 as a document table as shown in FIG. 1 is provided, and a document 8 to be copied is set on the contact glass 7. Around this contact glass 7 is a size indication frame 9 that serves as a guide when setting the original 8. Such original document 8 is sequentially digitally read by CCD scanner IO.

Here, the main scanning direction by this CCD scanner 10 is the Y-axis direction shown in FIG. 1, and the sub-scanning direction is the X-axis direction. The data read by the CCD scanner 10 is sequentially written onto the RAM map of the RAM 12 via the machine/○ board 11. At this time, the image data on the contact glass 7 is converted into coordinates according to the original size indication frame 9 (
For the X direction, O≦X≦XM^x, where XM^X is the number of scanning lines in the sub-scanning direction, and for the Y direction, Y
If M^X is the number of data for one line scan in the main scanning direction, then 0≦Y≦YM^X), which will be developed on the RAM map. Then, depending on the order of reading, the CPU
The image processing of this embodiment is performed by calling the data on 13.

First, in the read data, a certain threshold S
By detecting the following data, the reference side 9a of the size indication frame 9 is determined for the document 8 set on the contact glass 7.
4 m (X□, Y
□) is detected (if there is a document pressure plate that presses the document 8, the data from this document pressure plate is set to be at a level equal to or higher than the threshold S). This detection operation is performed using two counters 14, X and Y. This operation will be explained in detail. First, there is a certain point (
Let the data of x, y) on the RAM 12 be f(x, y). Therefore, first, f (0, O) and the threshold S are compared in magnitude. The result of this comparison is f (0,
If O)≦S, then a (Xi, Yl) =
This means that the coordinates of point a have been detected as (0, O). On the other hand, if f (0, O)>S, set the Y counter to 1
Then, compare f (0°1) with the threshold S. In this comparison, if f (0, 1)≦S, then a (x,, y,) = (o, i) and a
Let be the coordinates of the point. On the other hand, if f (0,1)>S,
The Y counter is further incremented by one and f (0,2) is compared in magnitude with the threshold S in the same manner. Like this
The value of the counter is increased one by one to detect the coordinates of a(Xt+Y1). Here, if a (x,, yt) is not detected even when compared with the threshold S up to Y=YMAX, then f (X, Y) = (1°o) and sequentially f (Xs Y) = ( 1e YMAX ) is sequentially compared with the threshold S and detected based on its magnitude. Such a detection operation is repeated in the same manner until a coordinate where the data of f (X, Y) is equal to or less than the threshold S is detected.

In other words, generally speaking, if f (X, Y)≦S, the coordinate detection of the corner point a is ended as a (X,, Y,) = (X, Y). And f (
If X, Y)>S and Y is not Y MAX, then f (
Compare X, Y+1) with threshold S, and
” If Y MAX, then f (X+1.O) and threshold S will be compared.

In this way, after detecting the coordinates (X-factor, Y□) of the corner point a of the document 8 closest to the reference side 9a, next, start from the corner point a of the other document 8 whose Y coordinate value is smaller. The coordinates of point C on the straight line connecting the corner points (X-=Y
2) is detected. The locus 1ull of this point C (xzt y
z) is basically detected in the same way by detecting the R
When the data on the AMII is f(X, Y), it is compared in magnitude with the threshold S. Here, since the corner point a is detected as the closest point to the reference side 9a, the X coordinate value cannot be less than X□ when detecting this point. It starts with a comparison with hold S.

If the result of this comparison is f (X, 0)≦S.

Sono mama b (X-2Yz) = (Xt-0).

This means that the coordinates of point b have been detected. On the other hand, f(xl,
If O)>S, increment the X counter by 1 and compare f (X + 1.O) with the threshold S. In this comparison, if f (X1+1゜O)≦S, then b (Xt, yz) = (X□+1,0) and b
Let be the coordinates of the point. On the other hand, f (X, +1.O)>S't
``If there is, increase the X counter by one more and f (X engineering + 2
．． o) and the threshold S are similarly compared. In this way, increase the value of the X counter one by one and b (
Detect the coordinates of Xzp yz). Here, X = X
, + m (m is any natural number between XM^X-X1, but it is about 1/1o of XM^X) even when compared with the threshold S, b (xzt yz)
is not detected, f (X, Y)= (X, ,
1) sequentially f (X, Y) = (Xt + m
-1) is sequentially compared with the threshold S and detected based on its magnitude. This detection operation is
(X.

The same process is repeated until a coordinate where the data of Y) is less than or equal to the threshold S is detected. In other words, if f (X, Y)≦S, then b (x, Y2) = (x, Y) is maintained and the coordinate detection of the corner point is completed. and f (X, Y)
>S, and if X is not X, +rn, then f (X, +1
．． Y) and the threshold S, X=X
, +m, then f (X,, Y+1) is compared with the threshold S. Here, by setting the domain of X to X1≦X≦X1+m, the time to detect the coordinates (Xt, Y,) of the point on ab can be shortened.

In this way, the coordinates of corner point a (X-factor) are determined.

Y t ) followed by the dot 'yA (Xt, yz)
is detected, the coordinates of both points a (Xi+Yt) +
The slope k of the straight line ab with respect to the other reference side 9b is calculated from b (XisY 2 ). That is, k= (y, -y,)/(x2-x,). Therefore, when the R document 8 is set parallel to the reference side 9a, the second detected point c (X21 yz) is a
coincides with the point, X,=X,, Y1=Y, and k=o
becomes. By taking the arctangent of this slope k, the angle α between the straight line ab and the reference side 9b (that is, the angle of inclination of the original 8 with respect to the reference side 9b) is calculated.

That is, it is determined as α=tan-1. Based on this inclination angle α, the rotation angle β (positive direction is counterclockwise as shown in FIG. (assumed to be taken in the direction) is determined by the following formula depending on the magnitude of the inclination angle α.

β=α (α≦π/4)β;α−(π
/2) (α>π/4) Therefore, in the case shown in FIG. 1, β=α.

After calculating the rotation angle β in this way, all the data of the read document 8 is rotated by the rotation angle β around an arbitrary coordinate point 1 in the document 8, for example, a corner point a (X,, YL). Move to coordinates.

Here, the coordinates of the read old data are (x, y), and the new coordinates after rotating by the angle β are (X').

Y'), this (X', Y') is determined by the following equation.

X' = (cosβ) X - (sinβ)Y+X
1Y' = (sinβ)X+(cosβ)y + y
l (In addition, when the center of rotation is arbitrary coordinates (xa, yo), X' = (cosβ)X-(sinβ)
y+x0, Y' == (sinβ) X + (c
osβ)Y+Y).

In this way, all data of stone piece m (X, Y) is converted to new coordinates (
x', y'), even if the original 8 is set diagonally, the straight line ab of the original 8 will be parallel to the reference side 9b of the original size indication frame 9, as shown by the broken line in FIG. This means that it is read in the same state as when it was set.

Therefore, only the data for the area of document 8 is valid. 1. ,,
Therefore, post-processing such as copying will be performed, as shown in Figure 5 (
A black border copy as shown in b) does not occur. As a result, the operator does not need to be very careful when setting the original 8 on the contact glass 7, resulting in good work efficiency. FIG. 3 is a flowchart showing the operation of such data rotation conversion processing.

On the other hand, the document 8 is placed on the contact glass 7 as shown in FIG.
Consider the case where it is set diagonally upward. Even in this case, the coordinates (
X,, Yl) are detected in the same way as in FIG. Next, among the straight lines on the side of the document 8 starting from this corner point a, a point on the straight line connecting corner point d extending in the direction where the Y coordinate becomes smaller; here, the coordinates of the corner point d (x z
= y z ) is detected. This detection is also performed in the same manner as in FIG. That is, the detection of corner point d is f (
X.

0) and the threshold S.

When the coordinates of both points a and d are detected in this way, the reference side 9
As mentioned above, the slope k of the straight line ad with respect to b is k= (Y
Calculated by l-Y, )/(x,-x,). Then, the tilt angle α is calculated from the value of this tilt k. in this case,
In Fig. 4, α>π/4 as shown, so the rotation angle β for rotationally converting the data is β;α−(7C/2)
and rotate it clockwise. In other words, like this α〉
When the angle is π/4, it is generally considered that the original has been rotated by (π/2) - α in the opposite direction to the case of original 8 where α≦π/4 shown in Fig. 1. The rotation angle β is selected and set according to the size of the angle α. The subsequent data processing is the same as in the case of FIG.

Note that the following method can also be adopted for detecting the coordinates of the second point following the coordinate detection of the corner point a.

In the case of FIG. 4, the coordinates of the corner point d are detected as described above. On the other hand, in the case of FIG. 1, the coordinates of another corner point e with respect to corner point a are detected as (X 3 , Y s ). To detect the coordinates of this corner point e,
Since the coordinates of corner point a are detected as a point closer to 0 on the Y-axis coordinate, on the assumption that the corner point e to be detected is closer to YNAX on the Y-axis coordinate, f The process may start from a comparison between (Xl, YNAX) and the threshold S. In this case too, X1~
The detection operation is between X1+m, and the coordinates in the Y-axis direction are sequentially incremented by -1. Then, the inclination of the document 8 is calculated as the inclination with respect to the reference side 9a. That is, in the case of FIG.

k' = (X, -X,) / (Y, -Y,),
In the case of FIG. 4, it is assumed that '=(x, -xl)/(y, -y,).

Then, from this inclination, the inclination angle γ of the document 8 with respect to the reference side 9a (in FIG. 1, equal to α) is calculated by taking the arctangent.Then, the rotation angle for data rotation conversion processing is the inclination angle γ In other words, if the positive direction of the inclination angle γ is determined, the inclination will be
The positive and negative signs of γ are different, and the positive and negative signs of the tilt angle γ are also different, so the tilt angle γ
All you have to do is rotate the data coordinates in the opposite direction by that amount.

Effects As described above, the present invention calculates the inclination angle of the document by detecting the coordinates of the corner point of the document closest to the reference side and a point on the straight line connecting other corner points, and calculates the inclination angle of the document. The coordinates are rotationally converted based on this tilt angle to obtain data parallel to the document size indication frame, so even if the document is set diagonally on the document table, the same image data will be obtained as if it were set parallel. This allows for good image post-processing, allowing the operator to
There is no need to pay close attention to the process, and the workability can be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a block diagram, FIG. 3 is a flowchart, FIG. 4 is a plan view showing different document setting states, and FIGS. 5(a) and (b). ) is a plan view showing a conventional example.

Claims (1)

[Claims] In a digital copying machine, etc., in which images of a document set on a document table equipped with a document size indication frame are sequentially digitally read by a light receiving section, the corner point of the document that is closest to the reference side of a predetermined document size indication frame. From the read data, detect the coordinates of the points on the straight line starting from the corner point of this document and other corner points from the read data, and calculate the document size of this document from the coordinates of these points. An image processing method for a digital copying machine or the like, characterized in that a tilt angle with respect to an instruction frame is calculated, and based on this tilt angle, all read data is rotationally converted into a data group of coordinates parallel to a document size instruction frame and output.