JPH0439114B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for rotating an image at an arbitrary angle in image processing technology.

[Prior Art] Generally, an affine transformation method is used as a conventional two-dimensional image data rotation method. To obtain a rotated image using this affine transformation, it is necessary to perform the calculation of equation (1). (Hereinafter, the explanation will be made using an x-y orthogonal coordinate system, with the horizontal direction as the x-axis direction and the vertical direction as the y-axis direction.) The coordinates x, y are the coordinates after transformation, and θ is the rotation angle of the image data. In this conversion, when handling image data such as images, it is necessary to perform the calculation of equation (1) for each pixel, so rotating an image with a particularly large area requires a huge amount of calculation and requires high speed. It was considered very difficult to obtain rotated images.

Further, FIG. 4 shows an arbitrary angle rotation method of an image shown in, for example, Japanese Patent Application No. 60-39813, in which 400 is a data section, 410 is a processing procedure,
420 is an image memory (hereinafter abbreviated as IM) that stores two-dimensional image data. Also,
401 is the rotation angle θ for rotating the two-dimensional image data, and 402 is the rotation angle x for rotating the two-dimensional image data.
An inclination angle θx, 403 for inclining the two-dimensional image data in the y-axis direction is an inclination angle θ _Y , 411 is a conversion angle determining unit, 412, 41
4 is an x-axis oblique axis conversion unit, 413 is a y-axis oblique axis conversion unit, 421 is original two-dimensional image data, 42
2,423 is two-dimensional image data of the rotation process, and 424 is rotated two-dimensional image data.

Next, the operation will be explained.

First, when the rotation angle θ401 of the image is given, the conversion angle determination unit 411 determines the tilt angle θx402 in the x-axis direction and the tilt angle _θY 403 in the y-axis direction. Next, the x-axis oblique axis converter 412 converts the IM4
The original two-dimensional image data 421 stored in the IM 20 is subjected to x-axis oblique axis transformation by the inclination angle θx 402 to generate second two-dimensional image data 422 and written to the IM 420 again. Next, the y-axis oblique axis transformation unit 413 performs y-axis oblique axis transformation on the two-dimensional image data 422 of the second rotation process by an inclination angle θ _Y 403, and converts the two-dimensional image data 422 of the second rotation process into two-dimensional image data 423 of the third rotation process. Create. Furthermore, the x-axis oblique axis conversion unit 414 converts the third two-dimensional image data 4
23 is subjected to oblique axis transformation by an inclination angle θx 402 to create rotated two-dimensional image data 424.

[Problem that the invention seeks to solve]

Since the conventional arbitrary angle rotation method for images is designed and configured as described above, it requires both functions of x-axis oblique axis conversion and y-axis oblique axis conversion.

On the other hand, the word structure of the IM 420 is normally a horizontal access method of approximately 16×1 bits as shown in FIG. Therefore, the x-axis oblique axis conversion can be easily realized by a raster operation based on shift and mask operations. However, regarding the y-axis oblique axis conversion, there was a problem in that the efficiency of raster operation was poor if the memory configuration was kept as described above, resulting in complicated procedures and a decrease in execution speed.

The present invention has been made to solve the above-mentioned problems.It prevents performance deterioration due to y-axis oblique axis transformation, which is not suitable for the above-mentioned memory configuration, and rotates image data at high speed with a simple procedure. The purpose of the present invention is to provide a device for rotating an image at an arbitrary angle.

[Means for solving problems]

An arbitrary angle rotation device for an image according to the present invention is an image rotation device for rotating an image at an arbitrary angle by oblique axis transformation in each direction of the x-axis and the y-axis. Axis oblique axis transformation, x axis oblique axis transformation and 90°
This is replaced by a combination of rotations.

[Effect]

The arbitrary angle rotation device of the present invention enables x-axis oblique axis conversion suitable for raster operations and y-axis oblique axis conversion with a simple 90° rotation, and is simple and fast. It is possible to rotate the image at any angle.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as in FIG. 4 are designated by the same reference numerals.
90° rotation processing unit, 101 is an x-axis oblique axis conversion unit, 1
03 and 104 are two-dimensional image data of the rotation process.

Next, the operation will be explained.

First, when the rotation angle θ401 of the image is given, the conversion angle determination unit 411 determines the tilt angle θx402 in the x-axis direction and the tilt angle _θY 403 in the y-axis direction. The method of determining the inclination angles θx 402 and θ _Y 403 in the conversion angle determining unit 411 is described in, for example, Japanese Patent Application No. 60
The following calculation formula shown in -39813 is used.

θx = θ/2 θ _Y = arc tan (sin - θ) ...(2) Next, the x-axis oblique axis conversion unit 412 transforms the original two-dimensional image data 421 stored in the IM 420 into the x-axis by the inclination angle θx402. Perform oblique axis transformation,
Second two-dimensional image data 422 is generated and written to IM 420 again. After that, it was originally the second
The two-dimensional image data 422 has an inclination angle θ _Y 4
03 is subjected to y-axis oblique axis transformation to generate fifth two-dimensional image data 423. However, in the present invention, this procedure is divided into the following three processes. The first is a 90° rotation to the right, the second is an x-axis oblique axis transformation, and the third is a 90° rotation to the left. First, the 90° rotation processing unit 100 rotates the second two-dimensional image data 422 to the right.
90° rotated third 2D image data 10
Create 3. The x-axis oblique axis transformation unit 101 performs x-axis oblique axis transformation on the third two-dimensional image data 103 by an angle θ _Y 403 to obtain a fourth two-dimensional image data.
Generate data 104. 90° rotation processing section 102
rotates the fourth two-dimensional image data 104 by 90 degrees to the left and generates fifth two-dimensional image data 4.
23 is generated. That is, the means for tilting in the vertical direction described in the claims includes the 90° rotation processing unit 100, the x-axis oblique axis conversion unit 101, and
This is to execute the 90° rotation processing unit 102.
Finally, the x-axis oblique axis transformation unit 414 performs x-axis oblique axis transformation on the fifth two-dimensional image data 423 by an inclination angle θx402, and the first two-dimensional image data 421 is rotated by an angle θ401. Sixth two-dimensional image data 424 is created.

Next, the x-axis oblique axis conversion unit 412 shown in FIG.
An example of oblique axis conversion in the x-axis direction at 101 and 414 will be described with reference to FIG. In the figure, 200 is the original two-dimensional image data stored in the IM 420, and 210 is the two-dimensional image data after x-axis oblique axis transformation. Also 201~
205 is two-dimensional image data obtained by dividing the original two-dimensional image data 200 into a plurality of blocks;
11 to 215 are two-dimensional image data obtained by transferring the divided two-dimensional image data 201 to 205, and 220 is a word structure (hereinafter abbreviated as segment) which is the minimum unit for accessing data in the image memory 420. ), 221, 22
2 is two consecutive words of image data that is a component of the original two-dimensional image data, 223,2
24 is image data after the image data 221 and 222 have been transferred, and 225 to 229 are the width of one transfer.

First, as shown in FIG. 2A, the original two-dimensional image data 200 is divided into two-dimensional image data 201 to 205 each having a number of rows corresponding to the angle of oblique axis transformation. Hereinafter, the divided two-dimensional image data will be referred to as a block. At this time, if the conversion angle is θx, the number of rows in each block is 1/tanθx. Next, each of the divided blocks 201 to 205 is transferred as shown below. Block 201 first
It is transferred to the position of block 211, which is another area within IM 420. Next, block 202 is shifted from block 211 by one dot, which is block 21.
Transfer to position 2. By transferring these operations in divided blocks up to block 205, each to a position shifted by 1 dot, the entire area of the original 2D image data 200 is subjected to x-axis oblique axis transformation, and the entire image becomes 2 Two-dimensional image data tilted by the angle θx, such as dimensional image data 210, can be obtained.

In order to realize the above operation, bit boundary transfer as shown in Figure 2 (b) is required, but this is necessary to transfer the image data 221 and 222 to the image data.
By performing shift and mask operations when transferring data to the positions of data 223 and 224, a transfer width of 22
This can be achieved by four transfers as shown by 5, 226, 227, and 229 or by three transfers with a transfer width of 225, 228, and 229. These operations are basic functions of raster operations and are generally known from horizontal smooth scrolling methods, etc., so details will be omitted.

Next, the 90° rotation processing section 100, 1 shown in FIG.
An example of 90° rotation in 02 will be described. Since rotation processing in 90° increments can be achieved with simple operations, many systems have dedicated hardware. The principle of this example is shown in FIG. In the figure, 300 is an n×n bit shift register. In the figure, the shift register 300 has two writing ports and two reading ports, and by combining these ports, it is possible to obtain rotated image data at high speed at 90° to the right and 90° to the left. In operation, the two-dimensional image data of n×n dots can be rotated in units of 90° by reading n-bit word units n times and then reading out the rotated data n times.

The embodiments of x-axis oblique axis transformation and 90° rotation processing have been described above, but the three x-axis oblique axis transformation units 412, 101, 414 shown in FIG. Function module also has two 90°
It goes without saying that the rotation processing units 100 and 102 can also be configured into one functional module since they perform the same processing. Therefore, the image data processing required for rotation of two-dimensional image data according to the present invention is as follows:
This is possible in two ways: x-axis oblique axis conversion and 90° rotation.

〔Effect of the invention〕

As described above, according to the present invention, the y-axis oblique axis transformation, which is not suitable for normal memory configurations, is divided into the x-axis oblique axis transformation and 90° rotation processing, so that the oblique axis transformation is used. This has the effect of realizing rotation of two-dimensional image data in a simple procedure and at high speed.

[Brief explanation of drawings]

Fig. 1 is a procedural diagram of rotation processing according to an embodiment of the present invention, Fig. 2 is an explanatory diagram showing an embodiment of oblique axis transformation in the x-axis direction, and Fig. 3 is an example of 90° rotation. 4 is a procedure diagram of a conventional rotation process, and FIG. 5 is a word configuration diagram of the image memory shown in FIG. 4. In the figure, 400 is a data section, 410 is a processing procedure, 420 is an image memory, 411 is a conversion angle determining section, 412, 101, 414 is an x-axis oblique axis conversion section, 100, 102 is a 90° rotation processing section, 4
21,422,103,104,423,424
is two-dimensional image data.

Claims (1)

[Claims] 1 An arbitrary angle rotation device for an image that stores two-dimensional image data in an image memory and generates a rotated image by tilting the two-dimensional image stored in the image memory in the horizontal and vertical directions. A first angle that is tilted horizontally from an angle and a second tilted vertically.
an x-axis oblique axis exchange unit that tilts the two-dimensional image data stored in the image memory horizontally by a first angle determined by the transformation angle determination unit; , a 90° rotation processing unit that rotates the two-dimensional image data stored in the image memory in units of 90°; and a 90° rotation processing unit that rotates the two-dimensional image data stored in the image memory with the x-axis oblique rotation processing unit. An arbitrary angle rotation device for an image, comprising means for controlling the image to be tilted in the vertical direction by a second angle determined by the conversion angle determination section using a combination with an axis exchange section.