JP2012226463A - Image rotation device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image rotation device and an image formation device that can suppress the capacity of a storage part used to rotate an image small.SOLUTION: An image rotation device 1 includes a first storage part 11 where image data is read and written in the same direction, and the number of pixels, corresponding to a predetermined burst length, in a first direction is equal to the number of pixels in a second direction orthogonal to the first direction; a second storage part 12 where the number of pixels in a third direction is equal to the number of pixels in the first direction in the first storage part 11 and the number of pixels in a fourth direction orthogonal to the third direction is less than the number of pixels in the second direction in the first storage part 11; and a read/write part 20 which reads out image data stored in the first storage part 11 by data of the number of pixels corresponding to the predetermined burst length and writes them to the second storage part 12, and reads out the data stored in the second storage part 12 by data of the number of pixels corresponding to the predetermined burst length and writes them to the first storage part 11.

Description

  The present invention relates to an image rotating apparatus that rotates an image based on image data, and an image forming apparatus that includes the image rotating apparatus.

  An increase in the image size and the number of bits per pixel of image data used in a digital camera, a copier, or the like is a seed for increasing the cost for an embedded system. One of image processing that is particularly noticeably affected is rotation processing. This is due to the fact that data handled by ordinary electronic equipment has a raster structure. In a digital camera, the camera itself needs to perform image rotation processing depending on whether the camera is used in a landscape or a portrait. Further, in the copying machine, when the direction of the original image read by the original reading unit is different from the direction in which the print image is formed on the paper, an image rotation process is required.

  The image rotation process is performed by picking up an appropriate pixel from the first storage unit in which the image data before the image rotation process is stored and placing the picked-up pixel at an appropriate position in the first storage unit. be able to. However, even though multiple pixels are arranged in the same memory word and the processing circuit that rotates the image has the ability to process multiple pixels in parallel, the image rotation processing is a process for each pixel. The processing speed is significantly reduced. In order to avoid this problem, in the normal rotation process, a second storage unit of n pixels × n pixels square (usually n is a power of 2) is arranged in the image rotation apparatus, and an n pixel grid is used on the tile. The divided pre-processing images are temporarily fetched into the second storage unit for each tile, rotated, and then transferred in tile units to the first storage unit that stores the rotated image.

  By the way, when rotating an image based on image data, the image rotation device arranges a plurality of unit-size rectangular image data in a line, and sets the data exceeding one side of the rectangular image data as a continuous address area. In some cases, memory access is made so that the burst length is longer than the unit-size rectangular image data to be rotated, and the unit-size rectangular image data is read and written. When the image to be rotated is a color image, the image rotation device packs the image data (for example, cyan, yellow, magenta, and black image data) of the color image that should be rotated at the same time, in the line direction. The address areas are arranged in a row and are continuous (see Patent Document 1).

JP 2008-136125 A

The image rotation process in units of 90 ° in the image rotation apparatus is simple, but has the following problems.
(1) The second storage unit used for image rotation processing has become difficult to obtain a small-capacity storage unit, and the operation speed has been increased, but the burst size has increased, and the efficiency of the small unit access is markedly high. It ’s bad.
(2) In order not to reduce the efficiency of the second storage unit, data must be read and written at a stretch in raster order, and a corresponding buffer memory is required in the processing circuit that rotates the image.

  Taking a DDR3 (Double-Date-Rate3) memory as an example, the minimum burst number of the memory is 8. In other words, the DDR3 memory has a prefetch length (burst size) of 64 bytes if it is a 64-bit width memory, and if it is less than 64 bytes, the performance drops sharply. This is because a data transfer smaller than a certain size becomes smaller than the internal processing word of the memory, and cannot operate faster than that internally.

  Further, the image rotation apparatus described in Patent Document 1 requires a memory (storage unit) capacity for processing image data of each color simultaneously when rotating a color image.

An object of the present invention is to provide an image rotation apparatus capable of suppressing the capacity of a storage unit used for image rotation.
Another object of the present invention is to provide an image forming apparatus including the image rotation device.

  The present invention is capable of storing image data, wherein the writing direction of the image data is the same as the reading direction of the image data, and the number of pixels corresponding to a predetermined burst length in the first direction, The first storage unit having the same number of pixels in the second direction orthogonal to the one direction and the image data can be stored, and the number of pixels in the third direction is the number of pixels in the first direction in the first storage unit. A second storage unit having the same number as the number of pixels in a fourth direction orthogonal to the third direction and less than the number of pixels in the second direction in the first storage unit, and image data can be stored. The number of pixels in the fifth direction is the same as the number of pixels in the third direction in the second storage unit, and the number of pixels in the sixth direction orthogonal to the fifth direction is the number of pixels in the fifth direction. The same third storage unit and the first storage unit or the previous The image data stored in the third storage unit is read for each pixel number corresponding to a predetermined burst length and written to the second storage unit, and the data stored in the second storage unit is stored in a predetermined burst. Read and write for each data of the number of pixels corresponding to the length and write to the first storage unit or the third storage unit, and image data stored in the first storage unit, A first operation for reading each first line data corresponding to a line in the first direction and writing for each line in the third direction of the second storage unit, and storing in the second storage unit after the first operation Image data to be divided into a plurality of second block data by dividing the image data into a plurality in the third direction, and reading the plurality of divided second block data in the third direction, the third storage unit The fifth direction of The second operation for writing in the sixth direction and the second block data stored in the third storage unit after the second operation by the second operation out of the fifth direction and the sixth direction. After reading out along the direction orthogonal to the direction in which the two block data is written and performing image rotation processing based on the second block data, the second block data subjected to the rotation processing is converted into the third direction. Read out the image data stored in the second storage unit after the third operation for each third line data corresponding to the line in the third direction. And a control unit that causes the read / write unit to sequentially execute a fourth operation of writing for each line in the first direction of the first storage unit.

In addition, the second storage unit has a number of pixels in the fourth direction of 1/4 ⁿ (n = 1, 2, 3,...) Compared to the number of pixels in the second direction in the first storage unit. Preferably there is.

  The present invention also relates to an image forming apparatus including the above-described image rotation device.

  The present invention can provide an image rotation apparatus capable of reducing the capacity of a storage unit used for image rotation, and an image forming apparatus including the image rotation apparatus.

It is a block diagram which shows the function structure of the image rotation apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating operation | movement of an image rotation apparatus. It is a figure for demonstrating the operation | movement of the image rotation in a 1st comparative example. It is a figure for demonstrating the operation | movement of the image rotation in a 2nd comparative example.

Hereinafter, an embodiment of an image rotation device of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a functional configuration of an image rotation apparatus according to an embodiment of the present invention.
The image rotation device 1 includes a first storage unit 11, a second storage unit 12, a third storage unit 13, a read / write unit 20, a control unit 30, and an input / output unit 40. The 1st memory | storage part 11, the 2nd memory | storage part 12, and the 3rd memory | storage part 13 are comprised from a hard disk, a semiconductor memory, etc. The second storage unit 12 is a working memory arranged inside the control unit 30 (integrated circuit).

  The first storage unit 11 can store image data. In the first storage unit 11, the image data writing direction and the image data reading direction are the same. Furthermore, in the first storage unit 11, the number of pixels corresponding to a predetermined burst length in the first direction (the number of pixels in the first direction) is the same as the number of pixels in the second direction orthogonal to the first direction. That is, the first storage unit 11 is a square.

The second storage unit 12 can store image data. The second storage unit 12 has the same number of pixels in the third direction as the number of pixels in the first direction in the first storage unit 11, and the number of pixels in the fourth direction orthogonal to the third direction is the first memory. The number of pixels in the second direction in the portion 11 is smaller. More specifically, in the second storage unit 12, the number of pixels in the fourth direction is 1/4 ⁿ (n = 1, 2, 3,...) Compared to the number of pixels in the second direction in the first storage unit 11. ··)It has become. That is, the second storage unit 12 has a size of 1/4, 1/16,..., Compared to the first storage unit 11.

  The third storage unit 13 can store image data. The third storage unit 13 has the same number of pixels in the fifth direction as the number of pixels in the third direction in the second storage unit 12, and the number of pixels in the sixth direction orthogonal to the fifth direction is the fifth direction. Is the same as the number of pixels. That is, the third storage unit 13 is a square. The third storage unit 13 is the same as the first storage unit 11. For this reason, the fifth direction and the first direction are the same direction. Further, the sixth direction and the second direction are the same direction.

  The read / write unit 20 reads out the image data stored in the first storage unit 11 or the third storage unit 13 for each data of the number of pixels corresponding to a predetermined burst length, and writes it in the second storage unit 12. . The read / write unit 20 reads the data stored in the second storage unit 12 for each number of pixels corresponding to a predetermined burst length and writes the data to the first storage unit 11 or the third storage unit 13. Do. More specifically, the read / write unit 20 (1) reads out data constituting the image data from the first storage unit 11 and writes the data to the second storage unit 12, and (2) from the second storage unit 12. Data is read and written to the third storage unit 13, (3) Data is read from the third storage unit 13 and written to the second storage unit 12, (4) Data stored in the second storage unit 12 is read Reading and writing to the first storage unit 11 are sequentially performed. Since the reading / writing unit 20 performs reading and writing for each data of the number of pixels corresponding to a predetermined burst length, the efficiency of reading and writing data does not decrease. The read / write unit 20 is controlled by a control unit 30 described later.

The control unit 30 causes the read / write unit 20 to sequentially execute the first operation, the second operation, the third operation, and the fourth operation.
The first operation is an operation of reading the image data stored in the first storage unit 11 for each first line data corresponding to the line in the first direction and writing it for each line in the third direction in the second storage unit 12. It is. As an example, when the first storage unit 11 has 64 pixels (first direction) × 64 pixels (second direction), the first operation is performed on 64 pixels (first direction) × 1 pixel (second direction). The corresponding first line data is read from the first storage unit 11 and written to the second storage unit 12.

  In the second operation, the image data stored in the second storage unit 12 after the first operation is divided into a plurality of second block data in the third direction to generate a plurality of second block data. The block data is read in the third direction and written in the fifth direction or the sixth direction of the third storage unit 13. As an example, when the second storage unit 12 is 64 pixels (third direction) × 16 pixels (fourth direction), the second operation is performed on 16 pixels (third direction) × 16 pixels (fourth direction). The second block data is read from the second storage unit 12 and written to the third storage unit 13 for each corresponding data.

  In the third operation, the second block data stored in the third storage unit 13 after the second operation is applied to the direction in which the second block data is written by the second operation in the fifth direction and the sixth direction. An operation of reading along the orthogonal direction and performing image rotation processing based on the second block data, and then writing the second block data subjected to the rotation processing to the second storage unit 12 along the third direction. is there. As an example, when the third storage unit 13 is 64 pixels (fifth direction) × 64 pixels (sixth direction), the third operation is 16 pixels (fifth direction) × 16 pixels (sixth direction). For each corresponding data, the second block data is read from the third storage unit 13 and written to the second storage unit 12.

  In the fourth operation, the image data stored in the second storage unit 12 after the third operation is read for each third line data corresponding to the line in the third direction, and the first direction in the first storage unit 11 is read. This is an operation of writing for each line. As an example, in the fourth operation, the third line data is read from the second storage unit 12 and written to the first storage unit 11 for each data corresponding to 64 pixels (third direction) × 1 pixel (fourth direction). .

  The input / output unit 40 is an interface used when image data is input / output to / from the image rotation apparatus 1.

Next, the operation of the image rotation device 1 will be described.
FIG. 2 is a diagram for explaining the operation of the image rotation apparatus 1. In the following, when the number of pixels in the fourth direction in the second storage unit 12 is ¼ of the number of pixels in the second direction in the first storage unit 11, the 90 ° rotation of the image is performed in two steps. This will be explained in the following.

Here, in FIG. 2, the direction indicated by the arrow (1) indicates the first direction, and the direction indicated by the arrow (2) indicates the second direction. The direction indicated by the arrow (3) indicates the third direction, and the direction indicated by the arrow (4) indicates the fourth direction. The direction indicated by the arrow (5) indicates the fifth direction, and the direction indicated by the arrow (6) indicates the sixth direction.
Furthermore, in the case illustrated in FIG. 2, the first storage unit 11, the second storage unit 12, and the third storage unit 13 have the following number of pixels. That is, the first storage unit 11 has 64 pixels in the first direction and 64 pixels in the second direction. The second storage unit 12 has 64 pixels in the third direction and 16 pixels in the fourth direction. The third storage unit 13 has 64 pixels in the fifth direction and 64 pixels in the sixth direction.

First, the image rotation apparatus 1 performs a first stage operation for rotating an image.
That is, first, the read / write unit 20 performs the first operation based on the control by the control unit 30. Specifically, the read / write unit 20 reads the first line data stored in the first line along the first direction among the image data stored in the first storage unit 11 (FIG. 2A). reference). Here, the number of pixels corresponding to the predetermined burst length is 64 pixels. Next, the read / write unit 20 writes the first line data read from the first storage unit 11 to the first line along the third direction of the second storage unit 12 (see FIG. 2B). ). Thereafter, in the same manner as described above, the read / write unit 20 sequentially reads the first line data stored in the second to 16th lines along the first direction of the first storage unit 11 for each line. The second storage unit 12 sequentially writes data from the second line to the 16th line along the third direction.

Next, the read / write unit 20 performs the second operation based on the control by the control unit 30. That is, the read / write unit 20 reads the image data stored in the second storage unit 12 for each second block data corresponding to the rectangular storage unit region, and stores the read second block data in the third storage. Writing is performed along the fifth direction or the sixth direction of the portion 13 (see FIG. 2C). The rectangular storage area has 16 pixels in the third direction and 16 pixels in the fourth direction.
Next, the read / write unit repeats the first operation and the second operation to change the image data stored in the first storage unit 11 into second block data. In the case shown in FIG. 2C, the second block data is written in the third storage unit 13 in the numerical order shown in the circle (along the fifth direction).

Next, the image rotation device 1 executes a second stage operation for rotating the image.
That is, first, the read / write unit 20 performs the third operation based on the control by the control unit 30. Specifically, the read / write unit 20 outputs image data (second block data) stored in the third storage unit 13 in a direction orthogonal to the direction in which the second block data is written (here, the second block data). (Six directions). Specifically, in the case shown in FIG. 2C, the second block data is stored in the third memory in the order of numbers “4”, “8”, “12”, “16” shown in circles. Read from the unit 13. Further, the read / write unit 20 rotates the image based on the second block data read from the third storage unit 13, and then transmits the second block data obtained by rotating the image along the third direction to the second storage unit. 12 are sequentially written. (See FIG. 2D).

Next, the read / write unit 20 performs the fourth operation based on the control by the control unit 30. That is, the read / write unit 20 reads out the third line data stored in the first line along the third direction from the image data stored in the second storage unit 12 (see FIG. 2D). Further, the read / write unit 20 writes the read third line data to the first line along the first direction of the first storage unit 11 (see FIG. 2E).
Thereafter, in the same manner as described above, the read / write unit 20 sequentially reads out the third line data stored in the second to 16th lines along the third direction of the second storage unit 12 for each line. Then, data is sequentially written from the second line to the 16th line along the first direction of the first storage unit 11. Further, the read / write unit 20 repeats the third operation and the fourth operation, so that all of the second block data stored in the third storage unit 13 becomes the third line data, and the first storage unit 11. Write to.
As a result, the image based on the image data stored in the first storage unit 11 is rotated by 90 °.

  In the second stage operation, the image rotation apparatus 1 can also use the second storage unit 12 as 16 pixels (third direction) × 64 pixels (fourth direction). In this case, the read / write unit 20 writes the second block data read from the third storage unit 13 to the second storage unit 12 without rotating. Further, the read / write unit 20 reads out the third line data corresponding to the line along the fourth direction from the second storage unit 12 and outputs the third line data along the second direction of the first storage unit 11. Write. In this case, the image rotation apparatus 1 can make the first storage unit 11 and the third storage unit 13 the same storage unit.

Note that the image rotation device 1 rotates the image by 90 ° when the number of pixels in the fourth direction in the second storage unit 12 is 1/16 of the number of pixels in the second direction in the first storage unit 11. Realized by staged operation.
First, as a first stage, the image rotation apparatus 1 uses the second storage unit 12 in a rectangle of 64 pixels (third direction) × 4 pixels (fourth direction). The first storage unit 11 has 64 pixels (first direction) × 64 pixels (second direction). In this case, the read / write unit 20 reads data corresponding to a region of 64 pixels (first direction) × 1 pixel (second direction) out of the image data stored in the first storage unit 11 four times. To the second storage unit 12. Next, the read / write unit 20 reads data corresponding to an area of 16 pixels (third direction) × 4 pixels (fourth direction) out of the image data written in the second storage unit 12 four times. To the third storage unit 13. Thereafter, in the same manner as described above, the read / write unit 20 reads the image data stored in the first storage unit 11 for each data corresponding to the area of 64 pixels × 1 pixel and writes it to the second storage unit 12. And reading the image data stored in the second storage unit 12 for each data corresponding to the area of 16 pixels × 4 pixels and writing it in the third storage unit 13 are repeated.

  Next, as a second stage, the image rotation apparatus 1 uses the second storage unit 12 with 16 pixels (third direction) × 16 pixels (fourth direction). In this case, the read / write unit 20 reads out data corresponding to an area of 16 pixels (fifth direction) × 4 pixels (sixth direction) from the image data stored in the third storage unit 13 four times. To the second storage unit 12. Next, the read / write unit 20 reads the data corresponding to the area of 4 pixels (third direction) × 16 pixels (fourth direction) out of the image data stored in the second storage unit 12 four times. And stored in the third storage unit 13. Thereafter, in the same manner as described above, the read / write unit 20 reads out the data corresponding to the area of 16 pixels × 4 pixels from the image data stored in the third storage unit 13 and stores it in the second storage unit 12. The writing is repeated and the image data stored in the second storage unit 12 is written in the third storage unit 13 with data corresponding to an area of 4 pixels × 16 pixels.

Next, as a third stage, the image rotation apparatus 1 uses the second storage unit 12 in a rectangle of 4 pixels (third direction) × 64 pixels (fourth direction). In this case, the read / write unit 20 reads the data corresponding to the region of 4 pixels (fifth direction) × 16 pixels (sixth direction) among the image data stored in the third storage unit 13 four times. To the second storage unit 12. Next, the read / write unit 20 reads out data corresponding to an area of one pixel (third direction) × 64 (fourth direction) out of the image data stored in the second storage unit 12 four times, It memorize | stores in the 1st memory | storage part 11. FIG. Thereafter, the read / write unit 20 reads the image data stored in the third storage unit 13 for each data corresponding to the area of 4 pixels × 16 pixels and writes it to the second storage unit 12 in the same manner as described above. And reading and writing the image data stored in the second storage unit 12 for each data corresponding to the area of 1 pixel × 64 pixels in the first storage unit 11 is repeated.
As a result, the image based on the image data stored in the first storage unit 11 is rotated by 90 °.

Next, a comparative example will be described.
First, the first comparative example will be described. FIG. 3 is a diagram for explaining the image rotation operation in the first comparative example. The first comparative example uses the same number of pixels (for example, 64 pixels × 64 pixels) in the first storage unit 101a and the same number of pixels (for example, 64 pixels × 64 pixels) in the second storage unit 102a. In this case, the image is rotated by 90 °.

First, the read / write unit 20 (not shown) sequentially reads the image data stored in the first storage unit 101a for each data of the number of pixels (for example, 64 pixels × 1 pixel) corresponding to the burst length ( 3A), and sequentially writes in the second storage unit 102a (see FIG. 3B). Next, the read / write unit 20 sequentially reads the data stored in the second storage unit 102a for each data of the number of pixels (for example, 1 pixel × 64 pixels) corresponding to the burst length (FIG. 3B). (Refer to FIG. 3C).
Thereby, in the image rotation operation in the first comparative example, the image based on the image data can be rotated by 90 °.

  Next, a second comparative example will be described. FIG. 4 is a diagram for explaining the image rotation operation in the second comparative example. In the second comparative example, the number of pixels in the second storage unit 102b is ¼ of the number of pixels in the first storage unit 101b. That is, in the second comparative example, the first storage unit 101b has 64 pixels × 64 pixels, while the second storage unit 102b has 32 pixels × 32 pixels.

First, the read / write unit 20 sequentially stores the image data stored in the first storage unit 101b for each data corresponding to a region of 32 pixels × 1 pixel (half the number of pixels corresponding to the burst length). The data is read (see FIG. 4A) and written sequentially into the second storage unit 102b (see FIG. 4B). Next, the read / write unit 20 sequentially reads the data stored in the second storage unit 102b for each data corresponding to an area of 1 pixel × 32 pixels (the number of pixels half the number of pixels corresponding to the burst length). (Refer to FIG. 4B) and write to the first storage unit 101b (refer to FIG. 4C).
Thereby, in the image rotation operation in the second comparative example, the image based on the image data can be rotated by 90 °.

  Here, in the image rotation operation in the second comparative example, the size of the image data transferred from the first storage unit 101b to the second storage unit 102b and the transfer from the second storage unit 102b to the first storage unit 101b. The size of the image data is ½ compared to the image rotation operation in the first comparative example. However, when data corresponding to the number of pixels equal to or less than the burst length is transferred, the time required for the transfer is the same. Therefore, the transfer time between the data corresponding to 32 pixels × 1 pixel and the data corresponding to 1 pixel × 32 pixels in the image rotation operation of the second comparative example is 64 in the image rotation operation of the first comparative example. The transfer time of the data corresponding to pixel × 1 pixel and the data corresponding to 1 pixel × 64 pixels is the same. Further, in the image rotation operation in the second comparative example, the number of times of data transfer is doubled compared to the image rotation operation in the first comparative example. Therefore, the performance of the image rotation operation in the second comparative example is ½ that of the image rotation operation in the first comparative example.

  Furthermore, as a third comparative example, when the second storage unit rotates the image 90 ° by using 1/16 the size (16 pixels × 16 pixels) of the first storage unit, The number of data transfers is four times that of the image rotation operation in the first comparative example. Therefore, the performance of the image rotation operation in the third comparative example is ¼ that of the image rotation operation in the first comparative example.

  On the other hand, in the image rotation apparatus 1 according to the present embodiment, when the image is rotated by 90 ° in two steps (the number of pixels in the second storage unit 12 is 1 / compared to the number of pixels in the first storage unit 11). 4), the number of accesses to the second storage unit 12 is doubled in all the steps. However, reading and writing of image data are all performed with high efficiency transfer, that is, transfer with a burst length. For this reason, the performance of the image rotation apparatus 1 when the 90 ° rotation of the image is realized by the two-stage operation is ½ that of the image rotation operation in the first comparative example.

  Furthermore, in the image rotation apparatus 1 according to the present embodiment, when the image is rotated by 90 ° in three stages of operation (the number of pixels in the second storage unit 12 is 1 / compared to the number of pixels in the first storage unit 11). In the case of 16), the number of accesses to the second storage unit 12 has increased three times in all steps. However, reading and writing of image data are all performed with high efficiency transfer, that is, transfer with a burst length. For this reason, the performance of the image rotation apparatus 1 when the 90 ° rotation of the image is realized by the three-stage operation is ３ compared to the image rotation operation in the first comparative example.

When the number of pixels in the second storage unit 12 is generalized to 1/4 ⁿ (n = 0, 1, 2, 3,...), The following Table 1 is obtained.

Here, the number of pixels in the second storage unit 12 is a value when compared with the reference number of pixels. For example, when the basic number of pixels is the number of pixels of the second storage unit 102a in the first comparative example, the second storage unit has 16 pixels × 16 pixels (second comparative example), and the second storage When the unit has 64 pixels × 16 pixels (this embodiment), the number of pixels in the second storage unit is ¼.
The performance (comparative example) when the size of the second storage unit 12 is a square is the number of pixels in the third direction and the fourth direction of the second storage unit 12 as described in the second and third comparative examples. Is a performance compared with the first comparative example when the values are equal to each other. The performance in the present embodiment is the performance when the image rotation device 1 of the present embodiment is compared with the first comparative example.
The performance (comparative example) when the size of the second storage unit 12 is a square is reduced in the order of 2 to the nth power, whereas the performance in the present embodiment is reduced by a linear expression. . Therefore, it can be seen that the image rotation apparatus 1 of the present embodiment is more advantageous as the size of the first storage unit 11 increases.

As described above, according to the image rotation device 1 of the present embodiment, the following effects are produced.
That is, the image rotation device 1 according to the present embodiment reads out the image data stored in the first storage unit 11 for each first line data corresponding to the line in the first direction, and stores the third data in the second storage unit 12. The first operation to be written for each line in the direction and the image data stored in the second storage unit 12 after the first operation are divided into a plurality of second block data in the third direction, and a plurality of second block data are generated. The second block data read out in the third direction and written in the fifth direction or the sixth direction of the third storage unit 13 and stored in the third storage unit 13 after the second operation. The second block data is read out along the direction orthogonal to the direction in which the second block data is written by the second operation in the fifth direction and the sixth direction, and the image is rotated based on the second block data. After doing The third operation for writing the processed second block data in the second storage unit 12 along the third direction, and the image data stored in the second storage unit 12 after the third operation in the third direction A fourth operation of reading for each third line data corresponding to the line and writing for each line in the first direction of the first storage unit 11 is sequentially executed. In this case, writing of each data and reading of each data are performed for each data of the number of pixels corresponding to a predetermined burst length.

  Such an image rotation apparatus 1 has the number of pixels corresponding to a predetermined burst length even if the number of pixels (capacity) of the second storage unit 12 is smaller than the number of pixels (capacity) of the first storage unit 11. Therefore, the efficiency of reading and writing data is not lowered. Further, in the image rotation device 1, the performance degradation caused by reducing the capacity of the second storage unit 12 is gradual (decrease in the primary expression). Therefore, the image rotation apparatus 1 can suppress the capacity of the second storage unit 12 used for image rotation.

Further, in the image rotation device 1, the second storage unit 12 has a fourth number of pixels in the fourth direction that is 1/4 ⁿ (n = 1, 2, 3) as compared with the number of pixels in the second direction in the first storage unit 11. ,···)It has become. The image rotation device 1 rotates the image by (n + 1) rotation operations per pixel. The rotation operation is a single rotation operation by writing data to the second storage unit and reading data from the second storage unit. Thereby, even if the pixel number (capacity) of the 1st memory | storage part 11 becomes large, the image rotation apparatus 1 can rotate an image with the 2nd memory | storage part 12 with a small pixel number (capacity | capacitance).

  Note that the image rotation device 1 is mounted on, for example, an image forming apparatus such as a copier, a multifunction peripheral, or a printer, or an electronic device such as a camera or personal computer. For example, when the image rotation apparatus 1 is mounted on an image forming apparatus, the image data is an external terminal connected by reading an image of a document by a document reading unit (not shown) or via a communication network. By being transmitted from (a personal computer or the like), it is stored in the first storage unit 11 via the input / output unit 40. Further, the image forming apparatus rotates the image based on the image data by the image rotating apparatus 1, then outputs the image data corresponding to the rotated image through the input / output unit 40, and outputs the image to the engine unit ( It can be formed on a sheet (image forming medium) by a not-shown.

DESCRIPTION OF SYMBOLS 1 ... Image rotation apparatus, 11 ... 1st memory | storage part, 12 ... 2nd memory | storage part, 13 ... 3rd memory | storage part, 20 ... Read-write part, 30 ... Control part

Claims (3)

The image data can be stored, the image data writing direction and the image data reading direction are the same direction, and the number of pixels corresponding to a predetermined burst length in the first direction is orthogonal to the first direction. A first storage unit having the same number of pixels in the second direction
Image data can be stored, and the number of pixels in the third direction is the same as the number of pixels in the first direction in the first storage unit, and the number of pixels in the fourth direction orthogonal to the third direction is A second storage unit that is less than the number of pixels in the second direction in the first storage unit;
Image data can be stored, and the number of pixels in the fifth direction is the same as the number of pixels in the third direction in the second storage unit, and the number of pixels in the sixth direction orthogonal to the fifth direction is A third storage unit having the same number of pixels in the fifth direction;
The image data stored in the first storage unit or the third storage unit is read and written to the second storage unit for each data of the number of pixels corresponding to a predetermined burst length, and stored in the second storage unit A read / write unit that reads the data to be read for each pixel number of data corresponding to a predetermined burst length and writes the data to the first storage unit or the third storage unit;
A first operation for reading the image data stored in the first storage unit for each first line data corresponding to the line in the first direction and writing for each line in the third direction in the second storage unit; The image data stored in the second storage unit after the first operation is divided into a plurality of second block data in the third direction to generate a plurality of second block data, and the plurality of second block data generated by the division Is read in the third direction and written in the fifth direction or the sixth direction of the third storage unit, and second block data stored in the third storage unit after the second operation Is read out along the direction orthogonal to the direction in which the second block data is written by the second operation out of the fifth direction and the sixth direction, and image rotation processing based on the second block data is performed. After going A third operation for writing the second block data subjected to the rotation process to the second storage unit along the third direction, and image data stored in the second storage unit after the third operation, A control unit that causes the read / write unit to sequentially execute a fourth operation of reading for each third line data corresponding to a line in the third direction and writing for each line in the first direction of the first storage unit; ,
An image rotation apparatus comprising: The number of pixels in the fourth direction of the second storage unit is 1/4 ⁿ (n = 1, 2, 3,...) Compared to the number of pixels in the second direction of the first storage unit. Item 2. The image rotation device according to Item 1.   An image forming apparatus comprising the image rotating device according to claim 1.

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