JPH01218174A - Image data expansion device - Google Patents

Abstract

PURPOSE:To expand image data swiftly by providing a line data buffer in/from which i-th expanded line data/(i-1)-th expanded line data is written/read as reference line data and a transmission data buffer that sequentially outputs expanded line data. CONSTITUTION:In the line data buffer 2, i-th expanded line data is written and simultaneously with it, (i-1)-th expanded line data is read therefrom as reference line data. The transmission data buffer 3 sequentially outputs expanded line data coming from an expansion processing circuit 1. When expanding in accordance with a two-dimensional decoding system, i-th compressed line data is accessed to the circuit 1, where said data is expanded by using reference line data from the buffer 3. As a result, the access time for compressed line data at the time of expanding can be shortened, and the image data can be expanded swiftly.

Description

[Detailed Description of the Invention] [Summary] An image data decompression device that uses a dedicated memory for storing reference line data necessary when decompressing compressed image data based on a two-dimensional encoding method, and provides compression during decompression. The purpose is to make it possible to decompress compressed image data at high speed by shortening line data access time. Among the compressed line data that makes up the compressed image data, the first compressed line data is one-dimensionally decoded. The second and subsequent compressed line data are expanded based on the method, and the compressed line data after the second is
In an image data decompression device equipped with a decompression processing circuit that decompresses based on a two-dimensional encoding method using reference line data before a line, the i-1th decompression is performed at the same time as the i-th decompressed line data is written. The decompression processing circuit is equipped with a line data buffer that reads line data as reference line data, and a transfer data buffer that sequentially outputs the decompressed line data from the decompression processing circuit. The i-th compressed line data is accessed and reference line data from the line data buffer is used to expand the i-th compressed line data.

[Industrial application field]

The present invention relates to an image data decompression device, and more particularly to an image data decompression device that uses a dedicated memory for storing reference line data necessary when decompressing compressed image data based on a two-dimensional encoding method.

As an example of an image data processing device, image data is recorded and stored in a recording bag such as an optical disk or a magnetic disk memory. There is an illing system. In this kind of filing system, image data obtained by scanning a document etc. is digitized by a scanner and then recorded in a recording device, but recording all the data in the image data is extremely difficult to record. equipment is required. Therefore, the image data is compressed before being recorded on the recording device.
When reproducing recorded image data, the original image data is restored by decompressing the reproduced compressed image data.

As compression/expansion methods for image data, there are, for example, one-dimensional encoding methods such as the MH encoding method used in facsimile, and two-dimensional encoding methods such as the MR encoding method.

[Conventional technology]

FIG. 4 shows the main parts of a conventional image data decompression device.

Image data scanned by a scanner (not shown) is stored in main memory 31 via common bus 30 .

The main memory 31 stores compressed image data etc. to ηC obtained by compressing line data 1 to 21 regarding each line of image data, as well as decompressed image data and data necessary for various input/output operations. . The decompression processing circuit 32 that decompresses image data is a common bus.

30, and the image data decompression processing circuit 3
This is done by referring to the MH code table 33 and the MR code table 34 connected to 2.

During decompression, the compression/decompression processing circuit 32 first accesses the first compressed line data flIc from among the compressed image data stored in the main memory 31 via the common bus 30 and refers to the MH code table 33. The first line data fl+ is restored by decompression. The restored line data 21 is supplied to, for example, a display device (not shown) via the common bus 30 for display, and is also stored in the main memory 31. Next, among the compressed image data, the second compressed line data lzc and the first expanded line data 1 as reference line data are transferred to the common bus 30.
, and by referring to the MR code table 34, the second line data No. 2 is restored by decompression. This restored expanded line data No. 2 is also supplied to the display device via the common bus 30 and stored in the main memory 31. In the same manner, the third and subsequent compressed line data l13cm1nc are sequentially expanded and restored to the original line data I13 to l1Tl, and finally the original image data (2+-en) is displayed on the display device.

[Problem to be solved by the invention]

Therefore, when performing two-dimensional decompression, it is necessary to sequentially read two line data from the main memory 31 in order to decompress one compressed line data.

That is, when decompressing one predetermined compressed line data, one decompressed line data as reference line data one line before the predetermined one compressed line data stored in the main memory 31 and one predetermined compressed line data Since it is necessary to sequentially access data via the common bus 30, the problem arises that it takes a long time to access the main memory 31, and it takes time to decompress compressed image data.

As a result, a problem arises in that it takes a long time to display the stored image data, and the waiting time before moving on to other processing operations is long.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image data decompression device that can decompress image data at high speed by shortening the access time of compressed line data during decompression.

[Means to solve the problem]

FIG. 1 is an explanatory diagram of the principle of the apparatus of the present invention. In the figure, 1 is an expansion processing circuit, 2 is a line data buffer, and 3 is a transfer data buffer. The decompression processing circuit 1 decompresses the first compressed line data among the compressed line data constituting the compressed image data based on a one-dimensional decoding method, and decompresses the second and subsequent compressed line data based on the previous line. Decompression is performed based on a two-dimensional decoding method using reference line data.

[Effect]

The line data buffer 2 writes the i-th expanded line data and at the same time reads the i-1th expanded line data as reference line data. The transfer data buffer 13 sequentially outputs the expanded line data from the expansion processing circuit 1. The decompression processing circuit 1 accesses the i-th compressed line data during decompression based on the two-dimensional decoding method, and uses the reference line data from the line data buffer 3 to decompress the i-th compressed line data.

Therefore, the access time for compressed line data during decompression can be shortened, and image data can be decompressed at high speed.

〔Example〕

FIG. 2 shows an embodiment of the invention. In the figure, the main memory 11 stores two-dimensionally encoded compressed line data Il.
It is assumed that compressed image data consisting of +c"-IlTlc is stored in advance. This main memory 11 also stores data necessary for various output operations, and decompressed image data is also stored in this main memory 11. be done.

At the time of decompression, the decompression processing circuit 12 first accesses the 11th compressed line data 2+c from the compressed image data stored in the main memory 11 via the common bus 14 under the control of the decompression control processor 13. code table 1
5, the first line data No. 1 is restored by decompression. The restored line data No. 1 is supplied to the line data buffer 16 and transfer data buffer 17 at the same timing. Line data buffer 1
Reference numeral 6 is composed of a memory, a register, etc. that can simultaneously write data for one line and read data for one line. The transfer data buffer 17 includes a first-in first-out (FIFO) register,
It is composed of a memory, etc., and buffers the decompressed line data from the decompression processing circuit 12, as well as main memory 1.
It has the function of specifying an address within 1. The line data f11 from the transfer data buffer 17 is transferred to the common bus 14.
The data is stored in, for example, the main memory 11 via the output port 18 and is supplied to the display device 19 for display. Next, the second compressed line data flzc in the compressed image data is accessed via the common bus 14, and the second compressed line data flzc read from the line data buffer 16 as reference line data is used to create the MR code table 20. By referring to , the second line data No. 2 is restored by decompression. This restored line data No. 2
Also line data buffer 16 and transfer data buffer 1
7 at the same timing. Line data 22 from transfer data buffer 17 is supplied to main memory 11 via common bus 14 and to display device 19 via common bus 14 and output port 18 . In the same manner, the third and subsequent compressed line data gc-et+c are sequentially decompressed and restored to the original line data Ils~1, and finally the original image data (Ils1~en) is stored in the main memory 1.
1 and displayed on the display device 19.

In this embodiment, the line data in the line data buffer 16 is updated every time the decompression processing circuit 12 performs decompression operation for one line, and the reference line data necessary for processing the next line is always updated. data buffer 16
is stored in

So, what about the decompression processing circuit 12 and the transfer data buffer? By updating the reference line data in the line data buffer 16 at the same timing as the image data is transferred to and from the main memory 17, the access time from the decompression processing circuit 12 to the main memory 11 can be shortened.

The line data buffer 16 also writes the expanded line data from the expansion processing circuit 12 and the expansion processing circuit 1.
Extended line data as reference line data to 2×
-1 can be read simultaneously, so the access time for reference line data can be reduced to the minimum. FIGS. 3(a) and 3(t)) show writing and reading of line data when the line data buffer 16 has a storage capacity for, for example, two lines.

Furthermore, since the transfer data buffer 17 is provided in this embodiment, the decompression processing circuit 12 starts decompression processing of the next compressed line data even if the transfer of one decompressed line data to the main memory 11 is not completed. can do. This is because each expanded line data is temporarily stored in the transfer data buffer 17, and the transferred data buffer 17 outputs the expanded line data to the common bus 14 at a transferable transfer speed. Therefore, even if the time required for the decompression processing of one compressed line data by the decompression processing circuit 12 is shorter than the time required for transferring one decompressed line data via the common bus 14, the decompression processing circuit 12 does not perform the decompression processing. It is possible to sequentially decompress compressed line data without having to hold data.

Although the present invention has been described above using examples, the present invention can be modified in various ways according to the gist of the present invention, and these are not excluded from the present invention.

〔Effect of the invention〕

According to the present invention, there is provided a line data buffer that reads the i-1th expanded line data as reference line data at the same time as writing the first expanded line data, and a transfer data buffer that sequentially outputs the expanded line data. The access time for compression line data during expansion can be shortened, and image data can be expanded at high speed, which is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a diagram explaining write and read operations of a line data buffer, and FIG. 4 is a conventional diagram. FIG. 2 is a block system diagram of main parts of the device. 1 to 3, 1 is a compression/decompression processing circuit, 2 is a line data buffer, 3 is a transfer data buffer, 11 is a main memory, 12 is a decompression processing circuit, 13 is a decompression control processor, 14 is a common bus, 15 is an MH code table, 16 is a line data buffer, 17 is a transfer data buffer, 18 is an output port, 19 is a display device, and 20 is an MR code table. Book, Sono Tangetsu (Zessho V Figure 1 (a) (b) Figure 3

Claims (1)

[Claims] Among the compressed line data constituting the compressed image data, the first compressed line data is decompressed based on a one-dimensional decoding method, and the second and subsequent compressed line data are
In an image data decompression device equipped with a decompression processing circuit (1) that decompresses based on a two-dimensional decoding method using reference line data before a line, the i-1th decompressed line data is simultaneously written. The decompression processing circuit comprises: a line data buffer (2) for reading the decompressed line data of the decompression line data as reference line data; and a transfer data buffer (3) for sequentially outputting the decompressed line data from the decompression processing circuit (1). , an image characterized in that the i-th compressed line data is accessed during decompression based on a two-dimensional decoding/combining method, and the i-th compressed line data is expanded using reference line data from the line data buffer. Data decompression device.