JPH05128246A - Control method for picture rotation - Google Patents

Abstract

PURPOSE:To use a frame memory of a rather small capacity, and to attain a picture rotation without any delay of the data writing and reading into the frame memory, in the method of rotating the picture by a desired angle by controlling the reading sequence of the picture data at the time of reading two-dimensional picture data stored in the frame memory. CONSTITUTION:In parallel to the reading of two-dimensional picture data D from a frame memory 16 by a second digital signal processor (DSP) 13, the new two-dimensional picture data D are written in the frame memory 16 by a first DSP 12 by setting a writing sequence in the same way as the reading sequence. Then, the picture rotation angle by the operation of the reading sequence is stored in a data memory 11, and at the time of reading the new two-dimensional picture data D next, the sum of the desired picture rotation angle with the rotation angle stored in the data memory 11 is searched by a CPU 10, and the picture rotation angle by the reading sequence of the picture data is set to the angle of the sum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for rotating an image carried by two-dimensional image data by a desired angle,
More particularly, the present invention relates to a method of rotating two read images while writing and reading two-dimensional image data to and from one frame memory in parallel.

[0002]

2. Description of the Related Art Conventionally, an image carried by two-dimensional image data is recorded as a hard copy, or a CRT is used.
When displaying on a display unit such as, for example, it is possible to record the portrait image and the landscape image without changing the orientation of the image to a direction convenient for the observer or changing the orientation of the rectangular hardcopy recording medium. Rotating a reproduced image by a desired angle is widely performed for the purpose of, for example,

As one of specific methods for rotating an image in this way, a method of operating the reading order of the image data when reading the two-dimensional image data stored in the frame memory is known. That is, for example, m digits xn
For a frame memory that stores two-dimensional image data of a row, data is stored in each row in the order of the first, second, third ,. Assuming that a non-rotational image is reproduced when the two-dimensional image data is input to the image reproducing means in the same order as this, the nth, n-1 ...
If the data is read in the order of rows and in the order of the first, second, third, ... Mth digits, the reproduced image will be rotated by 90 °.

By the way, when reproducing an image based on the above-mentioned two-dimensional image data, each two-dimensional image data relating to a plurality of images is successively transferred to the frame memory from an image reading device or an image filing device. Often comes. In such a case, in order to be able to reproduce images one after another in the order of image data transfer, it is indispensable to cause no congestion in writing and reading data to and from the frame memory.

[0005]

Therefore, in the past, two
A frame memory for images is prepared, and while writing the image data in one frame memory, the image data is read from the other frame memory and the image is rotated on the reading side as necessary. It was However, if a frame memory for two images is provided in this way,
The cost required for image rotation will increase considerably.

The present invention has been made in view of the above circumstances, and it is possible to use a frame memory having a relatively small storage capacity and rotate an image without congesting data writing and reading in the frame memory. It is an object of the present invention to provide a control method of image rotation capable of controlling the image rotation.

[0007]

As described above, the image rotation control method according to the present invention controls the image reading order when the two-dimensional image data stored in the frame memory is read. In the method of rotating a desired angle, in parallel with the reading of image data from the frame memory, a writing order is set similarly to the reading order, new two-dimensional image data is written in the frame memory, and the image by this reading is set. The rotation angle is stored in the storage means, and when the new two-dimensional image data is read out, the sum of the desired image rotation angle and the rotation angle stored in the storage means is calculated and the reading order operation of the image data is performed. The image rotation angle is set to the sum of the above angles.

[0008]

As described above, when writing and reading two-dimensional image data to and from one frame memory in parallel, the writing order of image data for each address must be the same as the reading order. I won't.
In other words, the writing order of the image data is determined by the circumstances of the image data reading side in parallel with it, regardless of what kind of rotation processing is performed after that. Is done.

The image rotation angle due to this writing has the same absolute value and opposite direction to the image rotation angle due to the reading in parallel therewith. That is, when the image rotation angle by reading is θ, the image is rotated by −θ by writing in parallel with it. Therefore, when the two-dimensional image data is written, the image rotation angle θ obtained by reading in parallel with the two-dimensional image data is stored in the storage means, and the angle (φ + θ) obtained by adding the angle θ to the desired rotation angle φ when the data is read later. If the image is rotated by (), the rotation amount at the time of writing is compensated, and the image is rotated exactly by the desired angle φ.

As described above, in the method of the present invention, it is sufficient if a frame memory having a storage capacity for one image is prepared, so that the method does not require an expensive frame memory and is a relatively inexpensive apparatus. Can be implemented by

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. FIG. 1 shows an example of an apparatus for implementing the image rotation control method according to the present invention. This device is composed of a general computer system or the like, and includes a CPU (central processing unit) 10, a data memory 11 connected thereto, and a first DSP (digital signal Processor) 12
And a second read-out which is also controlled by the CPU 10.
DSP 13 and data memory 14 connected to the first DSP 12
And a data memory 15 connected to the second DSP 13 and a frame memory 16.

The two-dimensional image data D input to the first DSP 12 is transferred to the frame memory via the data register 17.
Written to 16. This data writing is performed by the first DSP 12
Occurs and the address set in the address register 18 is designated in the frame memory 16 and executed. The two-dimensional image data D written in the frame memory 16 in this way is read by the second DSP 13 via the data register 19. This data read is performed by the second DSP.
13 is generated and the address set in the address register 20 is designated in the frame memory 16 and executed.

Here, the image output device 21 such as an optical scanning reading device for outputting the two-dimensional image data D to the first DSP 12 or an image filing device, as shown in (1) of FIG. It is assumed that the digital two-dimensional image data D for the pixel is output. The two-dimensional image data D is supplied to the first DSP 12 as data for the pixels in each row in the first, second, third, ... (m-1), m-digit pixel order (this pixel order is indicated by a solid line in FIG. The same applies to the following.), And in the order of pixel columns of the first, second, third, ... (n-1), n rows (this pixel column order is indicated by the dashed arrow in the figure. The same applies to the following. ) Must be entered. On the other hand, the second DSP
The image reproducing device 22 such as an optical scanning recording device or a CRT display device to which the two-dimensional image data D is input from 13 receives an image output device when the two-dimensional image data D is input in the same order as described above.
Play back the image in the same direction as the image output by 21.

The second DSP 13 changes the read order of the two-dimensional image data D stored in the frame memory 16 by operating the address to be set in the address register 20, and the image reproduced based on the read data is changed. Rotate with respect to the original image. In this embodiment, this rotation is performed at an angle of 0 ° (no rotation), 90 °, 180 °, or 270 °. Hereinafter, this image rotation will be described with reference to (2) onward in FIG.

First, consider the case where the two-dimensional image data D is input to the first DSP 12 in the order shown in (1) of FIG. 2 and the image data is written to the frame memory 16 in the same order as described above. .. In this case, when the two-dimensional image data D is read from the frame memory 16 in the reading order shown in (2) of the figure, the image reproduced by the image reproducing device 22 is rotated as shown in (6) of the figure. None, that is, the rotation angle is 0
It comes to °. On the other hand, the two-dimensional image data D from the frame memory 16 in the reading order shown in (3), (4) and (5) of FIG.
When is read, the orientation of the reproduced image is (7) in the figure,
As shown in (8) and (9), they are rotated by 90 °, 180 °, and 270 ° with respect to the original image, respectively. The image rotation angle is indicated by a positive value for counterclockwise rotation and a negative value for clockwise rotation.

Next, a case where the two-dimensional image data D relating to a plurality of images are sequentially stored in the frame memory 16 will be described with reference to FIG. First, the two-dimensional image data D (assuming that the character "F" is stored) stored in the frame memory 16 first is input in the order shown in (1) of FIG. 2) Frame memory 16 in the order shown in
Written in. For this first image, it is assumed that there is a request for 90 ° rotation, for example. In that case, the reading order of the two-dimensional image data D may be set in the direction shown in (3) of FIG. 2 (see (3) and (7) of FIG. 2). By doing so, the image reproduced based on the read two-dimensional image data D is rotated by 90 ° with respect to the original image as shown in (4) of FIG. This rotation angle of 90 ° is stored in the data memory 11 by the CPU 10.

Secondly, the two-dimensional image data D (assuming the character "G") stored in the frame memory 16 is stored in the first two-dimensional image so that the data transfer is not congested. The data D is read in parallel with the reading from the frame memory 16. The second two-dimensional image data D is also input in the order shown in (5) of FIG. 3, but the writing order is the same as the reading order of the first two-dimensional image data D. The orientation must be set as shown in (6). Therefore, this second image is rotated by −90 ° when writing to the frame memory 16.

The image carried by the second two-dimensional image data D is required to be rotated by 180 °, for example. At this time, the CPU 10 instructs the second DSP 13 to rotate 270 °, which is the rotation angle 90 ° stored in the data memory 11 added to 180 °. In other words, since the second two-dimensional image data D has been rotated by -90 ° during writing, 90 ° is added to compensate for this. Therefore, this second two-dimensional image data D
Are read in the order shown in (7) of FIG. 3 (see (5) of FIG. 2). The image reproduced on the basis of the two-dimensional image data D thus read is rotated by 180 ° with respect to the original image as shown in (8) of FIG.

As is clear from the above, at the time of data writing, data reading is performed in parallel with the data writing (the rotation angle is θ).
If there is a request to rotate the image rotated by the angle −θ for the reason that the original image is rotated by the angle φ, the rotation angle by the data read order operation may be set to (φ + θ).

The third two-dimensional image data D (assuming that the character "J" is stored) stored in the frame memory 16 is also input in the order shown in (9) of FIG. The second 2D image data D is written in the frame memory 16 in the order shown in (10) of FIG. In other words, this third image is rotated by -270 ° when writing data. Therefore, for example, when there is a request for 90 ° rotation for this image, the rotation angle by the read order operation is 90 ° + 270 ° = 360 °, that is, 0.
You can set it to °. Also, for example, when there is a request for 180 ° rotation, the rotation angle by the read order operation is 180 ° +
You can set it to 270 ° = 450 °, or 90 °.

The rotation angle θ obtained by reading the two-dimensional image data may be stored in the data memories 14 and 15 in addition to being stored in the data memory 11 as in the above embodiment. If you do so, the first DSP12 and the second DSP12
CPU10 gives the rotation angle instruction for the image with DSP13.
It may be configured to calculate the rotation angle by reading the image data when received from.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an apparatus for implementing an image rotation control method of the present invention.

FIG. 2 is an explanatory diagram illustrating a mechanism of image rotation in the image rotation control method of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between rotation by reading image data from a frame memory and rotation by writing image data in the frame memory in the image rotation control method of the present invention.

[Explanation of symbols]

 10 CPU 11, 14, 15 Data memory 12 1st DSP 13 2nd DSP 16 Frame memory 17, 19 Data register 18, 20 Address register 21 Image output device 22 Image reproduction device D 2D image data

Claims (1)

[Claims] 1. A method of rotating an image by a desired angle by operating a reading order of image data when reading two-dimensional image data stored in a frame memory, in parallel with the reading of the image data from the frame memory. hand,
When the writing order is set similarly to the reading order, new two-dimensional image data is written in this frame memory, the angle of image rotation by this reading is stored in the storage means, and the new two-dimensional image data is read out. Further, the control of the image rotation is characterized in that the sum of the desired image rotation angle and the rotation angle stored in the storage means is obtained, and the image rotation angle by the read operation of the image data is set to the sum angle. Method.