JP3346916B2 - Image rotation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image rotating apparatus for rotating an image stored in a memory in a bit map format in units of 90 DEG, and more particularly to an image rotating apparatus capable of rotating an image following a reading speed of a scanner. Related to a rotating device.

[0002]

2. Description of the Related Art Generally, when an image is rotated by 90 degrees, it can be realized by changing the reading direction of image data stored in a memory according to the rotating direction.

[0003] For example, as a method of displaying an image stored in a memory in a bitmap format by rotating the image in 90 ° units, an image of 1 × n × m × n dots as disclosed in Japanese Patent Laid-Open No. 1-200366 is known. A method has been proposed which has a memory that stores data in blocks of n × n dots and outputs the data in units of n dots, and controls reading of this memory by four up / down counters.

[0004]

For example, when a binary image is rotated in a digital copying machine, the output to the transfer paper is in 1-bit units. Since reading / writing is performed in byte units, the rotation conversion process is limited by byte boundaries. Therefore, the above-described conventional method has a problem that writing cannot be performed in 1-bit units following the reading by the scanner.

Further, in the above-mentioned conventional rotation method, since all the image data to be rotated cannot be read from the memory unless the rotation processing of the image data is completed and further stored in the memory, all the image data to be rotated can be stored. There is a problem that a memory having a large capacity is required. In addition, performing read processing of image data from the memory, rotation processing, and output processing of the rotated image from the memory at the same timing as the operation of the scanner and the printer imposes a burden on the circuit configuration, and reads the memory, There is also a problem that high-speed access is required for writing.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide an image rotating apparatus which can rotate an image following a reading speed of a scanner with a small memory capacity.

[0007]

In order to achieve the above object, a first means is to store a binary image data in a bitmap format, and to store the binary image data stored in the memory in units of 90 °. An address counter that reads out in units of bytes according to the rotation direction, bit extraction means that extracts each bit of the binary image data read out from the memory in units of bytes in accordance with the rotation direction, and extraction by the bit extraction means. And a line memory for two lines for alternately writing and reading the binary image data of the selected bits line by line.

The second means further comprises timing control means for writing the binary image data extracted by the bit extracting means in the first means to the line memory with a writing time sufficiently longer than a reading time. And

[0009]

According to the first means, the binary image data stored in the memory of the bitmap format is read out in byte units according to the rotation direction in units of 90 °, and each bit of the binary image data is read out in the rotation direction. Extracted accordingly. Therefore, the image can be rotated with a small memory capacity following the reading speed of the scanner.

In the second means, since the data is written to the line memory in a writing time sufficiently longer than the reading time, reading from the line memory can be completed even if the access time to the bitmap type memory is slow.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an image rotating apparatus according to the present invention, FIG. 2 is an external view showing a digital copying machine to which the image rotating apparatus of FIG. 1 is applied, and FIG. FIG. 4 is a side view showing a reading optical system, FIG. 4 is an explanatory view showing scanning of the digital copying machine of FIG. 1, FIG. 5 is an explanatory view showing an operation of rotating by 90 °, and FIG. 6 shows writing timing and reading timing of a FIFO memory. FIG. 7 is a timing chart, FIG. 7 is an explanatory diagram showing each read address when rotating by 0 °, 90 °, 180 °, and 270 °; FIG. 8 is a block diagram showing an image synthesizing device including the image rotating device of FIG. 1;
FIG. 9 is an explanatory diagram showing an example of combining by the image combining device of FIG.

First, an outline of a digital copying machine to which the image rotating apparatus of the present embodiment is applied will be described with reference to FIGS. 2 and 3, a document D is set on a document table 1 so that a reading surface faces downward, is illuminated by a light source 2, and its reflected light is reflected by a first mirror 3, a second mirror 4, and a third mirror 5. Is sequentially reflected and passes through the lens 6 to CC
It is read by the D line sensor 7. As shown in FIG. 4, the main scanning direction x of the document D is scanned by the CCD line sensor 7 for each of the lines l1, l2, and the sub-scanning direction y is determined by the relative movement of the document D and the reading optical system shown in FIG. Scanned.

Next, an image rotating apparatus according to the present embodiment will be described with reference to FIG. Image signals read by the CCD line sensor 7 are subjected to predetermined processing such as A / D conversion, shading correction, and binarization, and binary image data is stored in the memory 11 in a bitmap format. The memory 11 can write and read data in units of 1 byte by specifying an address. Therefore, reading from the memory 11 is performed in units of 8 pixels.

An X (main scanning direction) counter 12 and a Y (sub scanning direction) counter 13 convert the binary image data stored in the memory 11 by 90 ° under the control of the counter control unit 14.
Reading is performed in byte units according to the unit rotation direction. For example, in the case of rotating by 90 °, the data stored in the memory 11 is read from the lower left A to the upper left in byte units as shown in FIG. That is, in FIG.
When reading m × 8 bits in the direction, the X counter 12
Is fixed, the read address of the Y counter is decremented, and this operation is repeated eight times.

In the data read from the memory 11, the first (MSB) of each byte is extracted one bit at a time by the bit extraction unit 15 at the time of the first read, and the first data after rotation is output via the flip-flop (FF) 16. Line is FIFO
Stored in the memory 17a. Similarly, at the next read, the second bit of each byte is extracted one bit at a time, and the rotated second line is stored in the FIFO memory 17b.
Therefore, the data stored in the FIFO memories 17a and 17b is data obtained by rotating the data stored in the memory 11 by 90 degrees clockwise. When the rotation process for eight lines is completed in this way, the data is read from the position B in the figure.

The writing and reading by the FIFO memories 17a and 17b are performed by the timing controller 18 by the selection signal S.
Switching between the selectors 19a and 19b by EL and alternately for each line by a write enable signal WE and a read enable signal RE (toggle operation). The operation will be described with reference to FIG.
During a period in which the write enable signal WE becomes active in synchronization with the write clock CLK, the FIFO memory 17a,
17b, and are read from the FIFO memories 17a and 17b during a period in which the read enable signal RE becomes active.

A signal LGATE shown in FIG. 6 is a gate signal for writing an image on the transfer paper P, and corresponds to one line in the main scanning direction at the time of writing. X0 is a write start line, and output is started from the position S0 of the write start line X0. The write enable signal WE is sufficiently long with respect to the image data output period, and the output start position S0
Is written in the period of the write enable signal WE from the position P0 one line before.

Therefore, since the writing time is sufficiently long with respect to the output time of the image data, the reading from the memory 11 can be performed even if the access time to the memory 11 storing the image data is slow. The output from 17b can be made in time.
Also, the rotation of 180 ° and 270 ° can be realized by controlling the counting directions of the X and Y counters 12 and 13 by the counter control unit 14.

FIG. 7 shows 0 °, 90 °, 180 °, 270 °
The read address during rotation is shown. When the X and Y counters 12 and 13 rotate at 0 °, they both increment and start reading from the upper left, and when rotating at 180 ° both decrement and start reading from the lower right. Also, 2
At the time of 70 ° rotation, the X counter 12 increments from the upper right, and the Y counter 13 decrements.

FIG. 8 shows an image synthesizing circuit provided with the image rotation device 23 of the above embodiment.
1, image data “R” before rotation as shown in FIG. 9 is stored in advance. Then, the document is read by the scanner 21, and a known process is performed by the image processing unit 22. The image and the image data “R” rotated by 90 ° by the image rotation unit 23 are synthesized by the synthesizing unit 24, and the printer 25 Can be recorded on the transfer paper P.

[0021]

As described above, according to the first aspect of the present invention, the binary image data stored in the memory of the bitmap format is read out in byte units in accordance with the rotation direction in units of 90.degree. Since each bit of the image data is extracted according to the rotation direction, the image can be rotated with a small memory capacity while following the reading speed of the scanner.

According to the second aspect of the present invention, since data is written to the line memory in a writing time sufficiently longer than the reading time, reading from the line memory can be completed even if the access time to the bitmap type memory is slow.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an image rotation device according to the present invention.

FIG. 2 is an external view showing a digital copying machine to which the image rotation device of FIG. 1 is applied.

FIG. 3 is a side view showing a reading optical system of the digital copying machine of FIG. 1;

FIG. 4 is an explanatory diagram showing scanning of the digital copying machine in FIG. 1;

FIG. 5 is an explanatory diagram showing an operation of rotating 90 °.

FIG. 6 is a timing chart showing write timing and read timing of a FIFO memory.

FIG. 7 is an explanatory diagram showing read addresses when rotating by 0 °, 90 °, 180 °, and 270 °;

FIG. 8 is a block diagram showing an image synthesizing device including the image rotating device of FIG. 1;

FIG. 9 is an explanatory diagram showing an example of combining by the image combining device of FIG. 8;

[Explanation of symbols]

 Reference Signs List 11 memory 12 X counter 13 Y counter 14 counter control unit 15 bit extraction unit 17A, 17B FIFO memory 18 timing control unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06T 3/60 H04N 1/387 G09G 5/36

Claims (2)

(57) [Claims] 1. A memory that stores binary image data in a bitmap format, an address counter that reads binary image data stored in the memory in units of bytes according to a rotation direction in units of 90 °, Bit extracting means for extracting each bit of the binary image data read out in byte units according to the rotation direction; and alternately writing and reading binary image data of the bits extracted by the bit extracting means line by line. 2 for
An image rotation device comprising: a line memory for lines. 2. The two bits extracted by the bit extracting means.
2. The image rotation device according to claim 1, further comprising a timing control unit that writes the value image data to the line memory in a writing time sufficiently longer than a reading time.