JPH1127520A - Magnification and reduction processing unit for compressed image data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To magnify/reduce an image expressed in compressed image data without changing a sampling frequency by shifting the bits of a change point address denoting a change point of gradation of an image and writing the gradation information with the change point address after bit shift at a write address. SOLUTION: An address bit shifter 40 shifts a bit of a change point address ADD of compression data so as to generate a write address WADD of an image memory 44. Compression data ON/OFF information CNT is stored in the write address WADD. For example, the write address WADD is one half the original change point address by right-shifting the change pint address ADD by one bit each. Thus, the image whose change point address after shift is used for a write address is reduced by one half. Meanwhile, the image is magnified twice by left-shifting the change point address ADD by one bit each.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for processing compressed image data to generate image data representing an image obtained by enlarging or reducing an original image.

[0002]

2. Description of the Related Art In image processing using a computer, compressed image data is often used to reduce the amount of image data and save memory and transfer speed. Conventionally, when performing enlargement or reduction of an image represented by compressed image data, first, the compressed image data is expanded and the expanded image data is written to an image memory. Thereafter, the image data is read from the image memory, and the read image data is sampled at a sampling frequency corresponding to the enlargement / reduction ratio, thereby enlarging or reducing the image. For example, when enlarging an image by a factor of two, image data may be sampled at a sampling frequency that is twice as high as at the time of equal magnification.

[0003]

In the prior art, when enlarging or reducing an image, it was necessary to change the sampling frequency of the image data read from the image memory.
In particular, when the enlargement ratio is large, the sampling frequency increases, and the sampling clock signal is likely to be delayed.
When a delay occurs in the sampling clock signal, there is a problem that the quality of an enlarged image is deteriorated.

The present invention has been made to solve the above-mentioned problem in the prior art, and enlarges / reduces an image by changing a sampling frequency when sampling image data read from an image memory. It is an object of the present invention to provide a technique capable of enlarging / reducing an image represented by compressed image data without using a technique for performing the following.

[0005]

In order to solve at least a part of the above-mentioned problems, an image processing method according to the present invention processes compressed or enlarged image data by processing compressed image data. An apparatus for generating image data representing the image data, wherein the compressed image data includes, for each change point of the gradation of the image on a scanning line, a change point address indicating the position of the change point and a gradation after the change point Data representing an image on the scanning line based on the transition point address and the gradation information for each transition point, wherein the apparatus maintains the gradation information while maintaining the gradation information. A multiplying / reducing means for generating processed image data representing an enlarged or reduced image by multiplying the point address by a predetermined value; and an image memory for storing the processed image data. Obtain.

In this compressed image data, the gradation of the image after the position indicated by the change point address is indicated by the gradation information at the change point address. The image can be enlarged by multiplying the change point address by a value greater than one, while the image can be reduced by multiplying the change point address by a value less than one. Therefore, the image represented by the compressed image data is enlarged / reduced without using a technique for enlarging / reducing the image by changing the sampling frequency when sampling the image data read from the image memory. Can be.

Preferably, the enlargement / reduction means includes bit shift means for obtaining a value obtained by multiplying the change point address by a value of an integer power of 2 by bit shifting the change point address.

In this case, the multiplication of the change point address can be performed at a high speed.
Reduction processing can be executed at high speed.

The enlargement / reduction means further supplies the change point address after the bit shift to the image memory as a write address, and writes the gradation information at a memory position of the write address. And reading means for reading out the image data stored in the image memory in the order of addresses.

In this case, image data representing an enlarged or reduced image can be obtained only by writing the gradation information at the bit-shifted address position and reading the gradation information in the address order.

[0011]

Other Embodiments of the Invention The present invention includes the following other embodiments. A first aspect is a computer-readable recording medium in which a computer program for causing a computer to realize the functions of the respective means of the present invention is recorded.

A second aspect is an aspect as a program supply device for supplying, via a communication path, a computer program for causing a computer to realize the functions of each step or each means of the above invention. In such an embodiment, the above processing can be realized by placing the program on a server or the like on a network, downloading the necessary program to a computer via a communication path, and executing the program.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

A. Configuration of Apparatus: Hereinafter, embodiments of the present invention will be described based on examples. FIG. 1 is a block diagram illustrating a configuration of an image processing apparatus 20 according to an embodiment of the present invention. The image processing device 20 includes a CPU 22, a RAM 24, a compressed data processing circuit 26, a hard disk device (HDD)
27 and a bus 28 connecting these components.

The RAM 24 has a hard disk drive 27
Compressed image data stored in the compressed data processing circuit 2
6 stores a computer program for causing a computer to realize the function of the compressed data transfer unit 30 for transferring the data to the computer 6.

A computer program for realizing this function is provided in a form recorded on a computer-readable recording medium such as a flexible disk or a CD-ROM. The computer reads the computer program from the recording medium and reads the computer program into the internal storage device (RAM2).
4) Or transfer to an external storage device (HDD 27). Alternatively, a computer program may be supplied to a computer via a communication path. When implementing the functions of the computer program, the computer program stored in the internal storage device is executed by the microprocessor (CPU 22) of the computer. Further, a computer may read a computer program recorded on a recording medium and directly execute the computer program.

In this specification, a computer is
The concept includes a hardware device and an operation system, and means a hardware device that operates under the control of the operation system. In the case where an operation system is unnecessary and a hardware device is operated by an application program alone, the hardware device itself corresponds to a computer. The hardware device includes at least a microprocessor such as a CPU and means for reading a computer program recorded on a recording medium. The computer program includes a program code that causes such a computer to realize the functions of the above-described units. Some of the functions described above may be realized by an operation system instead of the application program.

The "recording medium" in the present invention includes a flexible disk, a CD-ROM, a magneto-optical disk, an IC card, a ROM cartridge, a punch card, a printed matter on which a code such as a bar code is printed, and an internal storage of a computer. Device (RAM, ROM, etc.)
And various computer-readable media such as an external storage device.

FIG. 2 is a block diagram showing the internal configuration of the compressed data processing circuit 26. Compressed data processing circuit 26
Includes an address bit shifter (ABS) 40, a data driver 42, an image memory 44, and an address generator 46.
And a data register 48. The address bit shifter 40 and the data driver 42 store the compressed data CD
This is a circuit for enlarging / reducing the image represented by, and writing image data representing the enlarged / reduced image into the image memory 44. On the other hand, the address generator 46 and the data register 48 are circuits for reading out image data from the image memory 44 and outputting it to the outside. The address bit shifter 40 and the address generator 46 are connected to an address terminal of the image memory 44. The data driver 42 and the data register 48 are connected to a data input / output terminal of the image memory 44. As the data driver 42, for example, a three-state buffer can be used. Further, an addition counter can be used as the address generator 46, and a flip-flop can be used as the data register 48.

The address bit shifter 40 corresponds to the bit shift means of the present invention, and is a path for connecting the address bit shifter 40 to the image memory 44 and a path for supplying data to the image memory via the driver 42. Corresponds to the writing means of the present invention. Further, the address generator 46 and the data register 48 correspond to the reading means of the present invention.

FIG. 3A shows the structure of compressed data, and FIG. 3B shows an image on one scanning line represented by the compressed data. As shown in FIG. 3A, this compressed data has a plurality of unit compressed data Q1 to Q4 to represent an image on one scanning line. Each unit of compressed data contains ON / OFF control information CNT
And a change point address ADD. The change point address ADD indicates a position where the gradation of the image changes on the scanning line. The ON / OFF control information CNT takes a value “01” when the position indicated by the change point address ADD is a start point (ON start) of an ON area (for example, a black area) of the image, and takes an OFF area (for example, When it is the start point (OFF start) of the white area), the value “0”
When "0" is the end point (line end) of the scanning line, the value "11" is taken. In other words, the ON / OFF control information CNT is gradation information indicating the gradation level of the image after the gradation change point indicated by the change point address ADD. As can be seen from FIG. 3B, the image reproduced by the compressed data is formed such that an area of the same gradation level (black or white) continues from each change point to before the next change point. .

FIG. 3C shows a state in which image data representing the image of FIG. 3B has been written into the image memory 44 based on the compressed data of FIG. In the image memory 44, the gradation level (ON or OFF) of the image indicated by the ON / OFF control information CNT is written at the address position indicated by the change point address ADD of the compressed data. When the image is not enlarged or reduced, the address bit shifter 40 (FIG. 2) operates at the changing point address AD.
D as the write address WADD as it is in the image memory 4
4 The ON / OFF control information CNT is
Regardless of whether the image is enlarged or reduced, the data driver 4
2, the image data is supplied to the image memory 44 as it is. Before writing the image data to the image memory 44,
All data in the image memory 44 has been initialized to zero.

When reading the image data from the image memory 44, the address generator 46 (FIG. 2) stores the read address RADD, which is sequentially increased from 0 by 1, in the image memory 4.
4 to read the image data stored in each read address position in order of address up to the line end. The read image data is held in the data register 48 and output to the outside. The address generator 46 and the data register 48 use the same sampling clock signal C
It operates in synchronization with LK, and the image data read from the image memory 44 is held by the data register 48 every time the read address RADD is updated. FIG.
In the example of (C), the image data from the address 0 to the address 7 are sequentially read. The read image data is supplied to, for example, a recording scanner (not shown), and an image shown in FIG. 3B is recorded on an image recording medium according to the image data.

FIG. 4 is an explanatory diagram showing an enlarged / reduced image and corresponding image data in the memory. FIG.
(B-1) and (B-2) correspond to FIGS.
This is the same as that shown in (C), and shows the case of the same magnification. 4 (A-1) and (A-2) show the case where the image is reduced to half, and FIGS. 4 (C-1) and (C-2) show the case where the image is enlarged twice. Is shown.

When the image is enlarged or reduced, the address bit shifter 40 (FIG. 2) generates the write address WADD of the image memory 44 by shifting the bit of the change point address ADD of the compressed data. The ON / OFF information CNT of the compressed data is stored in the write address WA.
Stored in the DD memory location. For example, FIG.
As shown in 1) and (A-2), when the image is reduced to １ ／, the write address WADD is generated by shifting the change point address to the right by one bit. This write address WADD is the same as the original change point address ADD.
１ ／. As shown in FIG. 4A-2, the image data written in the image memory 44 using the shift point address after the shift as the write address is the original image.
/ 2 represents an image reduced to / 2.

As shown in FIGS. 4 (C-1) and 4 (C-2), when the image is enlarged twice, the write address WADD is shifted by shifting the change point address left by one bit. Generate. This write address WADD is twice the original change point address ADD. The image memory 44 uses the change point address after the shift as a write address.
The image data written in the box represents an image obtained by enlarging the original image twice as shown in FIG. 4 (C-2).

In general, if the change point address ADD is shifted right by n bits, the image can be reduced to 1/2 ⁿ . On the other hand, if the change point address ADD is shifted left by n bits, the image can be reduced by 2 bits. It can be enlarged ⁿ times.
The direction of the bit shift and the shift amount are set in the address bit shifter 40 by the CPU 22. As described above, in this embodiment, the write address W to the image memory 44 is shifted by bit shifting the change point address ADD.
ADD is generated, and O is added to the position of the write address WADD.
By writing the N / OFF control information CNT, the image data representing the enlarged / reduced image is stored in the image memory 44.
Can be stored. Then, this image memory 44
Just read the image data in order from the address
It is possible to obtain reduced image data. This technique has the advantage that it is not necessary to change the frequency of the sampling clock signal CLK when the image data read from the image memory 44 is sampled by the data register 48 when the image is enlarged or reduced.

If a multiplier capable of multiplying the change point address ADD by an arbitrary number is used instead of the address bit shifter 40, the number is not limited to 2 ⁿ times and 1/2 ⁿ times.
It is also possible to enlarge or reduce the image at any magnification.
However, when the bit shifter 40 is used, there is an advantage that the operation of the multiplication is faster than when using another type of multiplier.

FIG. 5 is an explanatory diagram showing an example in which processing equivalent to FIG. 4 is realized by changing the compressed data itself. The compressed data shown in FIGS. 5 (A-1), (B-1) and (C-1) are the same as those shown in FIGS. 4 (A-1), (B-1) and (C-1).
-1) represents the same image as the data in the memory shown in FIG. As can be seen by comparing FIGS. 5 (A-1), (B-1) and (C-1), the compressed data representing the enlarged / reduced image is the original compressed data (FIG. 5 (B-1) )) Is obtained by multiplying the change point address ADD by a predetermined value. As described above, if the change point address of the compressed data is multiplied by a predetermined number, there is an advantage that the image can be enlarged or reduced without changing the compressed data.

The process of enlarging / reducing an image with the compressed data as it is can be executed by, for example, an application program realizing the compressed data transfer means 30. If the compressed data expanded / reduced in this manner is directly written into the image memory 44, the compressed data shown in FIGS.
-1) and (C-1) can be stored in the image memory 44, respectively.

FIG. 6 is an explanatory diagram showing an example of the structure of another compressed data to which the present invention can be applied. As shown in FIG. 6A, one unit of compressed data has an attribute ATR, tint% information TAR, and a change point address ADD. The attribute ATR takes a value “001” when the position indicated by the change point address is the start point of the tint area (area where the halftone dot area ratio is constant). If the image is an image in which data changes, "010" is taken, and if it is a line end, a value "111" is taken. When the position indicated by the change point address is a tint area, the tint% information TAR indicates a dot area ratio of the tint area. The attribute ATR and the tint% information TAR function as gradation information indicating the gradation level of the image after the gradation change point indicated by the change point address ADD.

FIG. 6C shows an example of an image represented by compressed data, and FIG. 6B shows the scanning line S in FIG. 6C.
5 shows an example of compressed data representing an image on L. In this example, a picture is pasted between addresses 300 to 450. The enlargement / reduction of the picture is performed by normal enlargement / reduction processing of the image separately from the above-mentioned enlargement / reduction processing. Thereafter, the enlarged / reduced picture image data is written to the image memory 44. As described above, even when a pattern is included in the entire image, the technique according to the present embodiment allows the image portion other than the pattern to be rapidly enlarged / reduced.
Enlargement / reduction processing can be accelerated as a whole.

It should be noted that the present invention is not limited to the above examples and embodiments, but can be implemented in various modes without departing from the gist thereof.
For example, the following modifications are possible.

(1) In the above embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software is replaced by hardware. You may do so.

(2) In the above embodiment, the gradation information is written only at the memory location indicated by the transition point address. It is also possible to write the same information as the gradation information of the address.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an image processing apparatus as an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a compressed data processing circuit 26.

FIG. 3 is an explanatory diagram showing a structure of compressed data.

FIG. 4 is an explanatory diagram showing an enlarged / reduced image and corresponding data in a memory.

FIG. 5 is an explanatory diagram showing an example in which processing equivalent to FIG. 4 is realized by changing compressed data itself.

FIG. 6 is an explanatory diagram showing an example of the structure of another compressed data to which the present invention can be applied.

[Explanation of symbols]

 Reference Signs List 20 image processing device 22 CPU 24 RAM 26 compressed data processing circuit 27 hard disk device 28 bus 30 compressed data transfer means 40 address bit shifter 42 data driver 44 image memory 46 address generator 48 Data register

Claims (3)

[Claims] 1. An apparatus for generating image data representing an enlarged or reduced image by processing the compressed image data, wherein the compressed image data is generated at each change point of a gradation of an image on a scanning line. Includes a transition point address indicating the position of the transition point and gradation information indicating a gradation after the transition point, and on the scanning line based on the transition point address and the gradation information for each transition point. Data representing an image, wherein the device generates processed image data representing an enlarged or reduced image by multiplying the change point address by a predetermined value while maintaining the gradation information. Means for enlarging / reducing compressed image data, comprising: means; and an image memory for storing processed image data. 2. The apparatus according to claim 1, wherein the enlargement / reduction means obtains a value obtained by multiplying the change point address by an integer power of 2 by bit-shifting the change point address. Comprising bit shifting means,
Enlargement / reduction device for compressed image data. 3. The apparatus according to claim 2, wherein said enlargement / reduction means further supplies said change point address after bit shift to said image memory as a write address, and An apparatus for enlarging / reducing compressed image data, comprising: writing means for writing the gradation information at a memory position; and reading means for reading image data stored in the image memory in order of addresses.