KR940005827B1 - Method for rotation of text image data - Google Patents

Abstract

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Description

How to rotate text image data

1 is a flowchart for explaining the flow of a 90 ° rotation process of a character image according to the present invention.

2 is a diagram of a device suitable for practicing the present invention.

3 is a drawing of a text image.

4 is a view in which the text image of FIG. 3 is rotated as it is.

5 is a diagram for explaining a conventional example.

6, 7 and 8 illustrate the problems of the prior art.

9 is a view in which the character image of FIG. 3 is rotated 90 degrees by the method of the present invention.

10 is a view showing an example in which the text image of FIG. 3 is rotated by -90 ° by the method of the present invention.

* Explanation of symbols for main parts of the drawings

21: input device 22: I / O port

23: control circuit 24: character image storage device

25: decoder circuit 26: phase rotation processing circuit

27: output device

The present invention relates to an image rotation processing method of character image data in which a character image is rotated by 90 ° or -90 ° at high speed and output in a character image processing apparatus or the like which stores a character image as its outline and generates a high quality character image. It is about.

As a method of storing a high quality character image, a method of extracting the outline of a character image and storing it as a set of N-th order curves, for example, has been proposed. In the present invention, a text image represents a binary image, which is an image represented by a combination of black pixels and white pixels.

As a method of extracting the outline of such a character image, storing the extracted outline as a set of N-th order curves, and restoring pixels of the outline from the outline information, for example, Japanese Patent Application Laid-Open No. 58-134745; 134748 publication.

In the methods disclosed in these methods, when outputting a text image stored as an outline, the pixels of the outline are first obtained from the set of N-th order curves. When the coordinates of the outline pixel are set to the ON and OFF signals of the light beam raster-scanned from the image sensor, the character image indicated by the outline pixel can be output as it is. Of course, by outputting the coordinates of the outline pixels to a bitmap storage device or the like and reading them at arbitrary addresses of the storage device, an output method other than raster scanning is also possible.

In the high quality text image processing apparatus, it is particularly important to rotate the text image by 90 degrees (or -90 degrees, or less). This is because the information of one character image can correspond to both horizontal writing and vertical writing. If it is possible to rotate a text image by 90 ° at a high speed by some method, it is clear that the rotation of only the contour pixel can be processed much faster than the rotation including the pixel inside the contour.

By the way, by simply rotating the outline pixel of the text image by 90 degrees, the text image rotated by 90 degrees cannot be obtained. The reason is explained by FIG. 3 and FIG.

3 is an example of a text image A placed on XY coordinates. In the XY coordinates described below, the Y direction corresponds to the main scanning direction at the time of output, and the X direction corresponds to the sub scanning direction. For example, when outputting a character image based on a pixel placed on XY coordinates by a laser printer or the like, a pixel (raster-scanned light ratio) on a line parallel to the Y-direction (hereinafter referred to as a line) is referred to. A character image can be generated by forming a pair of off-positions) and off-pixels (positions of raster-scanning light beams), turning on the light beams at the on-pixel position, and turning them off at the off-pixel positions. Can be.

In FIG. 3, the outline of the character image A is constituted by the pixels shown by the indicators G1 to G14. For example, the light beam is turned on at G1 of the first line (X = 1) and turned off at G14. Similarly, scanning to the line of X = 7 can reproduce this image A similarly.

4 is an example in which the contour pixels of G1 to G14 in FIG. 3 are simply rotated 90 ° clockwise. However, in FIG. 4, as shown in FIG. 3, the pair of on pixels and off pixels cannot be established. For example, lines (X = 1) to (X = 6) have only an odd number of contour pixels in each line. If you try to scan the line (X = 3) in this state, the light beam is first turned on at pixel G6 and then off at the position of pixel G5 once, again from the position of pixel G4, and then continues as it is. It's on. In this way, if there are only odd number of outline pixels on the same line, the text image is not output correctly.

As a method for solving such a problem, for example, it is possible to erase or interpolate a part of the rotated pixel. However, such a method remains problematic in terms of processing speed.

Therefore, the method of processing the upward rotation of a character image such as Unexamined-Japanese-Patent No. 60-75968 is considered. 5 is a diagram for explaining the preceding example. G21 to G42 are pixels representing the outline of a character image. One block showing one curve is formed from the pixels of G21 to G31, and the other block is formed of the pixels of G32 to G42. If the character image is a binary image, the outline pixel is a point indicating the start or end of the black pixel or the white pixel. Therefore, in the case of Fig. 5, the pixels G21 to G31 are blocks of on pixels (black pixel start) of the image, and G32 to G42 are blocks of off pixels (white pixel start). For example, G21 and G32, G22 and G33 are pairs of on and off pixels, respectively. The pixel which rotates 90 degrees at the position Xn, Yn of these outline pixels is calculated | required.

Rotate pixels within (| Yn-Y _{n + 1} | -1) intervals from the smaller pixel to one of the larger pixel among the pixels on the line of X = Xn. It is said to be outline pixel. The rotation process is performed in order of the pixels to be restored, that is, in the order of pixels in G21, G22, G23, G24,. Is done. When the rotation processing of the blocks of G21 to G31 is completed, the rotation processing of the blocks of G32 to G42 is performed. When the outline pixel thus obtained is rotated by 90 degrees, the pair of on and off pixels is necessarily established. However, in the description of FIG. 5, since the rotation processing is performed block by block, the pixels G21 and G32, and G31 and G42 are handled outside the block, so the rotation processing must be performed separately. Specifically, an attribute indicating on and off in G31 and G42 after rotation is added to output a character image indicated by the outline pixel according to the attribute.

By using the above method, the image rotation processing of the text image can be advanced. But a new problem came up here. For example, when sizing a character image as shown in FIG. 5, a part (pixel) of a block on or off side is omitted, and the on / off attribute of a block end point (G31, etc.) can take a correspondence. There will be cases when there is no. This is due to the fact that part of the block is omitted and deciphered for sizing (particularly shrinking), despite the idea that the block is rotated per block.

Another problem is that due to a computational error in obtaining contour pixels from the contour information of a character image indicated by a curve or the like, two blocks (pixels) to be paired become odd on a line or are alternately turned on and off. This is a problem that pairs of pixels do not hold. The reason is explained in FIG. 6, FIG. 7, and FIG.

6 focuses on the left end portion B of the character image. 7 is an enlarged view of part B of FIG. In FIG. 7, the limit of the calculation accuracy at the time of restoration is the pixel which G51-G56 is an on pixel and G57-G62 is an off pixel, and is located in the very near position like pixel G56, G62 on a line (X = 6), for example. There may be a gap caused by the problem. In other words, when restoring outline information indicated by a curve or the like, a calculation error occurs by rounding a numerical value equal to or less than arithmetic precision, so that a pixel of G62 may occur at the position of G56, and G56 may occur at the position of G62.

FIG. 8 (a) shows an example in which G56 and G62 in FIG. 7 are rotated by 90 degrees based on the staggered pixels. In this example, the character image of FIG. 7 is simply rotated for easy understanding, and the index G of each pixel is also the same.

In FIG. 8 (b), the index G was changed to H as a correct correction of this. As described in FIG. 5, each pixel is on a line of X = X _n , and Y _n , Y _{n + 1 from} the smaller pixel to one of the larger pixels (| Y _n -Y _{n + 1} Coordinate transformation is performed on the pixels within the interval of -1), and converted by interpolation between G51 and G57 in FIG. 7 and between H56 and G62. By the way, the pixel shown by H62 and H1 in FIG. 8 (b) is a pixel to which the attribute as a gentle element is added as a result of rotating FIG. 7 by 90 degrees, and therefore, the line (X = 1) of FIG. 8 (b). In this case, both H62 and H1 are turned on, so that pairs of on and off pixels are not established.

In this manner, in the method of FIG. 5, pixels such as staggers generated in narrow portions between blocks (curves) cannot be accurately rotated.

In order to realize the accurate rotation process which has been the subject of the prior art, the present invention makes it possible to perform 90 ° rotation of the contour pixel in one process. The characteristic shows a contour pixel P _n (n = 1, 2, 3 ...) which shows the outline of the character image on the XY coordinates in which the Y direction is the main scanning direction and the X direction is the sub scanning direction. In the image rotation processing method for rotating character image data, when there is a difference between the main scanning direction components Y _n and Y _{n + 1} of the adjacent contour pixels P _n and P _{n + 1} , the contour pixels P _n and P _{n +} If the sub-scanning directional component of ₁ to obtain a difference △ X of _n X _n, X _{n + 1,} the value of △ X _n corresponding to the contour pixel P _n 1 day in the case, and -1, in the case of 0 The pixels to be classified and rotated are obtained, and the obtained pixels are coordinate-transformed to generate the outline pixels of the rotated text image.

FIG. 1 illustrates a process for obtaining an outline pixel in which a character image outputted by main scanning in the Y-direction and sub-scanning in the X-direction is rotated by 90 ° as shown in FIG. 3 by the method of the present invention. It is a flow chart.

S1: Initial setting. Specifically, _n of the contour pixel P _n is designated as 1. In this example, n denotes the order in which each pixel is reconstructed from the outline information consisting of a set of N-th order curves representing the outline. For example, P ₂ is a pixel restored after P ₁ and output. In addition, the flag FS for determining the end of the process is set to zero.

S2: Input the coordinates of the pixel P _{n + 1} (X _{n + 1} , Y _{n + 1} ) indicating the outline of the character image. Specifically, the outline information of the character image is stored in the character image storage device 24 of FIG. 2, for example, and the coordinates of the outline pixel can be processed by restoring the outline information to the outline pixel in the decoder circuit 25. FIG. It can be expressed as a digital signal.

S3: _{Xn + 1} - _Xn is calculated | required, and it is called (DELTA) X. In the case of the present example, the X components of the pixel are increased or decreased only one by one, but it is clear that the case of increasing or decreasing the values by an arbitrary value N can be processed substantially the same. That is, in this example, DELTA X takes any one of 1, 0, -1.

S4: Compare Y _n and Y _{n + 1} , and if it is the same, go to S11 and set the flag FS to 1, otherwise go to S5. The next pixel P _{n + 1} and the pixel P _n without increase or decrease in the Y direction are not rotated.

S5: Y _S , Y _T are obtained as follows.

_{Y S = MIN [Y n,} Y n + 1] ( to a smaller one of the Y _n and Y _{n + 1} to Y _S)

Y _T = MAX [Y _n , Y _{n + 1} ] (large Y _n and Y _{n + 1} are defined as Y _T )

S6: It is determined whether DELTA X is 0. If 0, the process advances to S7, and if not, the process proceeds to S8.

S7: When P _n is an on pixel, the process advances to S9, and when it is an off pixel, the process proceeds to S10. When the decoding order goes from the left to the black pixel, P _n is an on pixel when ΔX is 1, and P _n is an off pixel when ΔX is −1.

S8: It is determined whether DELTA X is 1 or -1, and if it is 1, it advances to S9, and if -1, it advances to S10.

X

Y_T-1을 만족시키는 화소를 90°회전하여 화소 Q_i(X_i, Y_i)로 한다.S9: On any coordinates of contour pixels P _n , P _{n + 1} , they are on a line of X = X _n , and Y _S

X

A pixel satisfying Y _T -1 is rotated by 90 ° to form pixel Q _i (X _i , Y _i ).

Y

Y_T-1을 만족시키는 화소를 90°회전하여 화소 Q_i(X_i, Y_i)로 한다.S10: On any coordinates of the contour pixels P _n , P _{n + 1} , Y _{S is} on a line of X _n −1 and Y _S

Y

A pixel satisfying Y _T -1 is rotated by 90 ° to form pixel Q _i (X _i , Y _i ).

S11: It is determined whether or not to end the processing. If flag FS is 1, the process ends. If 0, it goes to S12.

S12: Add 1 to n.

S13: Return to A if n + 1 exists.

S14: The n + 1st one is set to 1. This is to completely process between the start point and the end point of the process.

S15: The flag FS is set to one.

2 is an embodiment of a device suitable for practicing the present invention. Reference numeral 21 is an input device for inputting character image information and various commands, for example, a keyboard of a console or a floppy disk drive. 22 is an I / O port that is an interface, and 23 is a control circuit for overall control and data transfer.

24 denotes a character image storage device which stores a pattern of a character image by its outline information, and 25 denotes a decoder pixel and restores outline information of the character image stored in the character image storage device 24 as outline pixels. Reference numeral 26 denotes a phase rotation processing circuit, which performs the phase rotation processing as shown in FIG. 1 by the command of the control circuit, and converts the reconstructed outline pixel to the pixel rotated upward. Numeral 27 denotes an output device for restoring and outputting a text image in accordance with data such as a contour pixel that has been rotated up, for example, a CRT of a laser printer or a console.

When a command for outputting a text image rotated by 90 ° is input from the input device 21, it is transmitted to the control circuit 23 through the I / O port 22. The control circuit reads out the contour information from the text image storage device 24 and sends it to the decoder circuit 25 according to the instruction. The decoder circuit 25 restores the contour information that has been transmitted to the contour pixel. The data of the contour pixels output by the reader circuit are transmitted to the phase rotation processing circuit 26 sequentially. The phase rotation processing circuit 26 outputs the transferred contour pixel data as the contour pixel data obtained by the phase rotation processing.

The outline pixel data of the image rotated by 90 ° is transmitted to the output device 27 through the I / O port, and the output device 27 outputs a text image based on the transmitted outline pixel data.

9 is an example of a character image in which the character image A of FIG. 3 is rotated 90 degrees clockwise by the method of the present invention.

First, as a third-degree pixels P ₁ G1 (X1, Y4), the pixel _{G2 P 2 (X2, Y2)} . Next, Y _S and Y _T are obtained as shown in S5 of FIG.

Y _S = MIN [Y ₁ , Y ₂ ] = 2

Y _T = MAX [Y ₁ , Y ₂ ] = 4

It becomes

Since ΔX ₁ = 1, the pixel Q _i is obtained according to the law shown in S9 of FIG. On the line of the equation X = X _n = 1 of the straight line, the point in which the value of the Y direction is rotated by 90 ° of pixels (X1, Y2) and (X1, Y3) included in a section of 2 or more and 3 or less, (X2 , Y7) and (X3, Y7) are pixels Q ₁ and Q ₂ rotated by 90 degrees. These two points are pixels H33 and H32 in FIG.

Next, when the pixel G2 and the pixel G3 of FIG. 3 are examined, assuming that the pixel G3 is P ₃ (X3, Y1),

Y _S = 1

Y _T = 2

It becomes Since ΔX ₁ = 1, the pixel Q ₁ is obtained according to the law shown in S9 of FIG. And on the line X = 1, the value of the Y-direction are one pixel (X2, Y1) the 90 ° rotation point (X1, Y6) is the pixel Q _3. In FIG. 9, this Q ₃ is shown as the pixel H34. In the same manner below, the rotation processing of the pixels in FIG. 3 is performed.

Next, a description will be given when ΔX = −1 described in S8 of FIG. In this case, the pixel Q ₁ is obtained according to the law shown in S10 of FIG. For example, the pixel G8 of FIG. 3 is referred to as P ₈ (X7, Y7), and the pixel G9 is referred to as P ₁₀ (X6, Y8). As in the case of ΔX = 1, when Y _S and Y _T are obtained,

Y _S = 7

Y _T = 8

It becomes

On the line of X = X _n −1, the points X7 and Y2 at which the values in the Y-direction rotated 90 degrees of pixels X6 and Y7 by 90 degrees become Q7. In FIG. 9, the pixel is H27. You can do the same below.

Next, the case of ΔX = 0 explained in S6 of FIG. 1 will be described. In this case, Q ₁ is obtained according to the laws of S9 and S10 depending on whether the outline pixel P _n is an on pixel or an off pixel, as shown in FIG. For example, in the pixel G7 and G8 of FIG. 3, (DELTA) X = 0, G7 is an on pixel and G8 is an off pixel. Therefore, G7 obtains pixel Q ₁ from S9 in FIG. ₁ to obtain pixel H25 in FIG. The pixel G8 obtains the pixel Q ₁ by S10 in FIG. ₁ , and obtains H26 in FIG.

As described above, the image is converted to the outline pixel as shown in FIG. 9, but even if the pixel shift as described in FIG. 7 and FIG. 8 occurs, whether the pixel after rotation is an on pixel or an off pixel is determined as the position of the pixel. Since there is no on pixel or off pixel as an attribute, it is possible to reproduce a character image rotated exactly 90 degrees.

In this example, the case where the rotation angle is 90 degrees has been explained. However, the rotation processing of -90 degrees can be easily realized by modifying the conversion processing in S9 and S10 of FIG. 1 as follows.

X

Y_T-1을 만족하는 점을 -90도 회전하여 화소 Q_i(X_i, Y_i)로 한다.S9 is on a line of X = X _n +1 on some coordinates of contour pixels P _n , P _{n + 1} , and Y _S

X

The point satisfying Y _T -1 is rotated by -90 degrees to be the pixel Q _i (X _i , Y _i ).

Y

Y_T를 만족하는 좌표의 화소를 -90도 회전하여 화소 Q_i(X_i, Y_i)로 한다.S10 is on a line of X = X _n at any coordinate of the contour pixels P _n , P _{n + 1} , and Y _S

Y

The pixel with coordinates satisfying Y _T is rotated by -90 degrees to be the pixel Q _i (X _i , Y _i ).

In this way, it is possible to cope with a rotation of -90 degrees by only slightly changing the process shown in FIG.

FIG. 10 shows an example in which the character image A shown in FIG. 3 is rotated by -90 degrees. First, the pixel G1 of FIG. 3 is P ₁ (X1, Y4) and the pixel G2 is P ₂ (X ₂ , Y ₂ ). ΔX ₁ is 1 at this time. Next, Y _S and Y _T are obtained as shown in S5 of FIG.

Y _S = MIN [Y ₁ , Y ₂ ] = 2

Y _T = MAX [Y ₁ , Y ₂ ] = 4

It becomes

Since ΔX ₁ = 1, the pixel (X) is on a line of X = X _n + 1 = 2 according to the modification of FIG. ₂ , Y ₂ ) and (X ₂ , Y ₃ ) are rotated by -90 °, and (X6, Y2) and (X5, Y2) are rotated by 90 °, and pixels Q ₁ and Q ₂ are rotated by 90 °. Pixels H76 and H75 in the figure. In the same manner, a rotating pixel is obtained and all pixels are converted to outline pixels rotated by -90 °.

As described above, in the text image processing apparatus which has generated a text image of high quality by storing the text image as its outline, it is possible to reproduce the text image rotated by 90 ° more accurately at high speed.

Claims (2)

Character image data representing contour pixels P _n (n = 1, 2, 3, ...) representing the outline of the character image on the XY coordinates in which the Y direction is the main scanning direction and the X direction is the sub scanning direction. phase in the rotation processing method, adjacent the edge the pixel P _n, P _{n +} main scanning direction component Y _n, the sub-scan direction when the difference between the Y _{n + 1,} said contour pixel P _n, P _{n + 1} of the _first to A pixel which is obtained by obtaining the difference ΔX _n of the components X _n and X _{n + 1} , and classifying and rotating as the case _where the value of X _n corresponding to the outline pixel P _n is +1, -1, and 0 And a coordinate pixel of the obtained pixel to generate an outline pixel of the rotated character image. The method of claim 1, wherein when ΔX _n is +1, when the pixel rotates by 90 °, the line (parallel to the main scanning direction) of X = X _n is formed among the contour pixels P _n and P _{n + 1} . In the main scanning direction components Y _n and Y _{n + 1} of the contour pixels P _n and P _{n + 1} from one pixel to the one in front of the large pixel | Y _n -Y _{n + 1} | If ΔX _n is -1, and the pixel in -1 section is a rotating pixel, adjacent contour pixels P _n and P are on the line of X = X _n -1 (parallel to the main scanning direction). _{n + 1} main scanning direction component Y _n , Y _{n + 1 from} the smaller pixel to one of the larger pixels | Y _n -Y _{n + 1} | If the pixel to rotate the pixels within the interval of -1 and, △ X _n is 0, if the contour pixels P _n pixel indicating the position on the light beam, such as a raster scan △ X _n + 1 in this case and asking for the pixel rotating manner, the contour pixel P _n, seeking a pixel by rotating, such as when one pixel is △ X _n -1 indicating a position off the light beam, such as a raster scan, obtained In this way A method of image rotation of character image data, characterized by generating a contour pixel of a character image rotated by 90 ° by coordinate conversion of pixels.

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