JPH04145765A - Image decoder - Google Patents

Abstract

PURPOSE:To display the reduced screen at high speed by decoding only a specific block in encoded image data, and also, executing a thin-out image processing before decoding it. CONSTITUTION:A decoding means 6 regards one scanning line as one block in encoded data, and by a counting/integrating means 10, the number of scanning lines in the encoded data is integrated. In such a way, a counted/integrated value immediately after the number of n-th scanning lines is counted and integrated comes to (n), therefore, only when this counted/integrated value satisfies nMODm=1 (m denotes an arbitrary natural number), decoding of an n-th scanning line is executed by the decoding means 6, and in other case, decoding is not executed, and a processing for detecting the next EOL code is executed. In such a way, the part corresponding to (m)-1. pieces of scanning lines can be skipped without executing the decoding which takes time for the processing, and the processing can be executed at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a decoding device for encoded data into image data. The present invention relates to an image decoding device that performs expansion by decoding while thinning out sections for the purpose of obtaining a reduced image when expanding data that has been compressed by encoding and stored.

(Prior Art) For high-speed retrieval and display of image data, which has been attracting attention in recent years, high-speed decoding and display technology is important. Among these, techniques for displaying thinned images are useful.

Mod is a typical conventional code/decoding method.
ifiecl Huffman (hereinafter referred to as MH)
Code/decoding method, Modifier Re1ati
ve ElementAddress Designa
te (hereinafter referred to as MR) code/decoding method, Dis
There is a create Co51ne Transform (hereinafter referred to as DCT) code decoding method.

FIG. 1 shows a flowchart of image data processing in the image decoding apparatus of the present invention, and in any of the above-mentioned code/decoding systems, conventional image processing has been performed as shown by the broken line.

That is, the complete original image data D1 appearing on the bus line 9 is encoded by the encoding means 1 to become encoded data D2 appearing on the bus line 2, and the data D stored in the storage means 3 is read out by the reading means 4. The entire encoded data D4 appearing on the bus line 11 is decoded by the decoding means 6, complete original image data D is obtained on the bus line 12, thinned out by the thinning means 8, and the thinned image data D is sent to the bus line 7. I was trying to get it.

(Problem to be Solved by the Invention) As described above, conventional thinned image processing is performed on complete original image data D obtained by decoding all encoded data D4 reproduced on bus line ll. Ta. However, since the resolution of image display processing is generally inferior to the resolution of the complete original image data D generated on the bus line 12, this conventional method also decodes image data that is known not to be displayed from the beginning. The present invention solves these conventional problems and provides a method for displaying a reduced screen at high speed. The purpose of the present invention is to provide an image decoding device that is capable of decoding images.

(Means for Solving the Problem) In order to solve the above problem and achieve the object, the invention according to claim (1) provides a device for decoding encoded data into image data, which comprises: means for detecting one section from encoded data; means for counting and integrating the number of sections detected by the detection means; and means for decoding one section of the encoded data; The present invention is characterized in that the partition is decoded only when the accumulated count value n immediately after the count accumulation satisfies n MOD m = 1 for any natural number m.

Further, the invention according to claim (2) provides an apparatus for decoding encoded data into image data.

comprising means for detecting one sub-section from the encoded data, means for counting and accumulating the number of sub-sections detected by the detection means, and means for decoding one sub-section of the encoded data, The present invention is characterized in that the sub-divisions are decoded only when the counted integrated value J immediately after counting and accumulating the number of sub-divisions satisfies j MOD i = 1 for any natural number 1.

(Function) In the present invention, the encoding process of image data and the reading process of stored data are performed as before, but only a specific section of the encoded image data is decoded, and the data is thinned out before decoding. It performs image processing to enable high-speed display of reduced screens.

(Example) First, Example 1 of the invention according to claim (1) of the present invention
This will be explained with reference to the flowchart of the image data processing shown in FIG. The solid line part in the figure shows the part of the present invention.
o is a counting and accumulating means installed immediately before the decoding means 6 in the subsequent stage, which integrates the number of scanning lines in the encoded data, and the other numbers 1, 3, and 4 correspond to the already explained encoding means, storage means, and reading means.

In the first embodiment, the MH code decoding method is used as the encoding means l. This MH code decoding method is a type of one-dimensional code decoding method, and uses only the correlation between pixels within one scanning line. In this method, the state of a pixel is represented by two values, white or black. The length of consecutive white or black pixels (hereinafter referred to as
Complete original image data D is output to the bus line 9 by encoding the MH code tables given for white runs and black runs respectively (denoted as white runs and black runs, respectively).
1 compression. Then, an E OL (000000000001) codeword, which is a terminal codeword, is added to the end of each scanning line. It goes without saying that, in order to facilitate the detection of the EOL code during decoding, which will be described later, it is possible to achieve higher speed by encoding by using pad bits and aligning with byte/word boundaries as is well known.

The decoding means 6 in the first embodiment regards one scanning line as one section in encoded data. Since the aforementioned EOL code is given to the end of each scanning line, it is easy to detect one section. The counting and accumulating means 10 accumulates the number of scanning lines in the encoded data.

In this way, the cumulative value immediately after counting and integrating the number of n-th scanning lines is n, so this n is n MOD m = 1 - (1) where m is any natural number. It is.

The decoding means 6 decodes the n-th scanning line only when the following is satisfied, and in other cases, no decoding is performed and the next EO
A process for detecting the L code is performed. In this way, a portion corresponding to m-1 scanning lines can be skipped without performing decoding, which takes time.

Note that if the image data D, / with thinned scanning lines generated at high speed using the image decoding apparatus of the present invention is displayed as it is on a CRT display or the like, a horizontally long screen will be displayed. Therefore, in order to display a screen that has been reduced so that the aspect ratio of the image is 1:1, it is necessary to thin out the generated image data in the horizontal direction as well. However, since this horizontal thinning process also takes time, it is possible to display a plurality of horizontally long screens simultaneously for the purpose of visual search.

Next, a second embodiment of the invention according to claim (1) will be described using FIG. 1. The MR code decoding method described above is used as the encoding means 1 in the figure.

The MR code decoding method is a type of two-dimensional encoding method,
After one scanning line is encoded using the MH code decoding method, 11 scanning lines are subsequently two-dimensionally encoded according to the K factor.

In the decoding means 6 in the second embodiment, 1 in the encoded data
A portion corresponding to a scanning line is regarded as one section. Since an EOL code is given to the end of each scanning line equivalent portion, it is easy to detect one section. As in the first embodiment, the number of sections in the encoded data is integrated by the counting/integrating means 1o.

In the MR code decoding method, only the part corresponding to the scanning line that satisfies (2) is encoded with the MH code, and the corresponding section is independent. can be decrypted to

Therefore, if the section is decoded only when the above formula (2) is satisfied, 11 sections will have been skipped before decoding. In this way, an image obtained by reducing the complete original image data appearing on the bus line 9 to 1/K in the vertical direction is obtained.

Note that if one section is regarded as a part corresponding to KXp (p is a natural number) scanning lines starting from a part corresponding to a scanning line encoded with the MH code in the encoded data, and the image decoding apparatus of the present invention is applied, It is also possible to obtain a screen that is reduced by 1/(KXp) in the vertical direction.

Next, regarding Example 3 of the invention according to claim (1),
This will be explained with reference to a conceptual diagram of partitions of encoded data in FIG. 2 and a block diagram of decoding in FIG. 3.

In the third embodiment, the DCT code decoding method is used as the encoding means 1 indicated by block 301 in FIG. In the following description, the DCT code decoding method will be briefly explained, and sections in encoded data will be explained with reference to FIG. 2, and then a third embodiment will be described.

First, the DCT code decoding method is a type of two-dimensional code decoding method, in which transform coefficients by two-dimensional DCT, which is a type of orthogonal transform, are Huffman encoded for direct current (hereinafter referred to as DC) components. The alternating current (hereinafter referred to as AC) component is run-length Huffman encoded. This encoding converts the original image into a plurality of blocks 1, 2, . . . each having pXp (p is a positive integer) pixels. . . , after dividing into r, this is performed for each block one by one. After one block encoding is completed, an EOB code (End of B) is used as a block end word.
lock) (see Figure 2).

Among the transform coefficients obtained by two-dimensional DCT, the DC component is subjected to one-dimensional prediction with neighboring blocks, and then the one-dimensional prediction error is Huffman encoded. In this embodiment, a DCT code decoding method that performs one-dimensional prediction in the direction of the horizontal scanning line X is applied. That is, in the third embodiment, inter-block correlation exists only in the horizontal direction and not in the vertical direction.

Next, a section of encoded data, which is a unit of decoding necessary for applying the present invention, will be described. FIG. 2 shows a conceptual diagram of the division, and the AC component encoded data in the two-dimensional DCT transform coefficients are independent in units of pxp blocks of the image data, but the DC component encoded data is 1 in the X direction of the horizontal scanning line. In order to perform dimensional prediction, each p horizontal scanning line of image data is independent.

Therefore, for image data, one section 201 is a digital image data group of p horizontal scanning lines, and for encoded data, one section 201 is for an encoded data group of the image data group.
Set it to 2. Here, the size of the image data in the direction of the horizontal scanning line X is q (however, q is a natural number multiple of p).

), the number of blocks in the direction of horizontal scanning line X is r =
Since q/p, there are r EOBs in the partition. Therefore, the integrated count value S of the EOB code is s MOD r = 1 −−−−−−(3
) The end of the encoded data group that satisfies the following is the end 20 of one section.
It becomes 3. That is, the end of the image data group in units of p scanning lines becomes the end 203 of one section.

In the decoding device of the present invention, at the time of decoding, the encoded data is thinned out by integrating the end word E○B of the block and the end number of the sections of the encoded data using a counting accumulation means. Perform decryption.

In the decoding block diagram shown in FIG.
All encoded data D is inputted to line 302 from encoding means 1, storage means 3, and readout means 4 (the above are based on the embodiment) indicated by 01, and EOB is detected on line 304 by EOB detection means 303. Output a signal.

The EOB detection signal is input to the EOB number counting/accumulating means 305, and an EOB number counting integrated value S is outputted to a line 306.

The calculated value of the EOB count is input to the section end detection means 307, and only when the above equation (3) is satisfied, a section end detection signal is outputted to the line 308. The section end detection signal is input to the section number counting integration means 309, and the section number counting integrated value n is outputted to the line 310. Decoding means 3 for the cumulative value n of the number of sections
11, decodes only the sections that satisfy the above equation (1), and outputs thinned image data D, / to line 312.

Note that if the image data D, / with thinned scanning lines generated at high speed using the image decoding apparatus of the present invention is displayed as it is on a CRT display or the like, a horizontally long screen will be displayed. Therefore, in order to display a screen that has been reduced so that the aspect ratio of the image is 1:1, it is necessary to thin out the generated image data in the horizontal direction as well. However, since this horizontal thinning process takes time, it is possible to display a plurality of horizontally long screens at the same time for the purpose of visual search.

Next, an embodiment of the invention according to claim (2) of the present invention will be described using a decoding block diagram shown in FIG.

In this embodiment, the DCT code decoding method described above is used as the encoding means 1 indicated by block 401 in FIG.

In the following description, sub-partitions in encoded data will be described, followed by examples.

However, the DCT code decoding method, partition, block, AC component, and DC component referred to here are based on the third embodiment.

First, one subsection of encoded data, which is a unit of decoding necessary for applying the present invention, is defined as one block. Therefore, the end word EOB code of the block becomes the end of the subpartition. As a result, the DC components are not independent between subdivisions, but the AC components are independent. Further, the decoding device of the present invention uses counting and accumulation means in decoding,
The encoded data is thinned out in the vertical and horizontal directions by adding up the number of ends of sub-divisions and the number of ends of sections of encoded data, and then decoding is performed.

In the decoding block diagram shown in FIG.
Encoding means 1 indicated by 01, storage means 3. Reading means 4
(Hereinafter, the same applies to Embodiment 1), EOB detection means 303.
EOB count accumulating means 3052 section end detection means 307
And the section number counting integrated value n inputted to the line 402 from the section number counting integrating means 309 (the above corresponds to the third embodiment) is equivalent to the section number counting integrated value n in the third embodiment. Here, only when the division count integrated value n satisfies the above formula (1), the divisions of the decoded data are separated into AC components and DC components, and the following processing is performed.

Regarding the AC component, the sub-section end detection means 403 outputs a sub-section detection signal to the line 404.

The sub-division detection signal is input to the sub-division number counting and accumulating means 405, and the sub-division number counting integration value J is outputted to a line 406. The sub-section count integrated value J is input to the decoding means 407, and for any number i, jMODi=1...
. . . Only when (4) is satisfied, sub-sections are decoded and AC component thinned image data is output to line 408.

Further, regarding the DC component, the decoding means 409 outputs DC component image data to a line 410. The DC component image data is converted into a line 412 by the pixel number calculation and accumulation means 411.
The pixel count integrated value V is output to.

The pixel count integrated value V is input to the thinning means 413, and v
DC component thinned image data is output to line 414 only when MOD i = 1 - (5) is satisfied.

The image data of the AC component and the DC component are inputted to the integrating means 416 via a line 415, and the interrupted image data D,' is outputted to a line 417.

In addition, especially by setting 1=m (any natural number),
It becomes possible to obtain a thinned image with the same aspect ratio as the original image.

(Effects of the Invention) As explained above, the decoding device for encoded image data according to the present invention thins out scanning lines and sections before decoding image data, so unnecessary processing can be omitted. , which has the advantage of speeding up processing. Moreover, since the encoded data to be stored has the same definition as before, it is possible to display and print at the original definition if necessary.

[Brief explanation of drawings]

1 to 3 show embodiments of the invention according to claim (1) of the present invention, and FIG. 1 is Embodiment 1 and Embodiment 2.
FIG. 2 is a conceptual diagram of partitions of encoded data, FIG. 3 is a block diagram of decoding according to the third embodiment, and FIG. 4 is a claim (2) of the present invention. FIG. 2 shows a block diagram of decoding in an embodiment of the described invention. 1, 301.401... encoding means, 3...
Accumulating means, 4...Reading means, 5...EO
L detection means, 6, 311.407.409-decoding means, lO... counting accumulation means, 201... 1 section of digital image data, 202... 1 section of coded data,
203... End of section, 303... EOB check-to-side ratio, 305... EOB number counting integration means, 307... Section end detection means, 309... Section number counting integration means, 40
3... Sub-section end detection means, 405... Sub-section number counting and accumulation means, 411... Pixel number counting and accumulation means, 4
13... Thinning means, 416... Integrating means.

Claims (2)

[Claims] (1) A device that decodes encoded data into image data, comprising: means for detecting one section from the encoded data; means for counting and accumulating the number of sections detected by the detection means; means for decoding one section of the encoded data, and decoding the section only when the cumulative value n immediately after counting and accumulating the number of sections satisfies nMODm=1 for any natural number m. An image decoding device characterized by performing decoding. (2) A device that decodes encoded data into image data, comprising means for detecting one sub-section from the encoded data, and means for counting and accumulating the number of sub-sections detected by the detection means; means for decoding one sub-section of the encoded data, when the cumulative count value j immediately after counting and accumulating the number of sub-sections satisfies jMODi=1 for any natural number i. An image decoding device characterized in that the image decoding device decodes only the sub-sections.