JP2865016B2 - Image playback 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 reproducing apparatus for decompressing compressed image data using a CPU.

[0002]

2. Description of the Related Art When an image is digitized and stored or transferred to a storage medium such as a CD-ROM or a hard disk, simply digitizing an image would require a huge amount of data. After that, it is stored or transferred.

[0003] There are various types of compression coding systems, and JPEG (Joint Photograph) is available.
ic Expert Group) or MPEG (Mov
ing Pictures Expert Grou
Those based on the discrete cosine transform (DCT) adopted in international standards such as p) are often used.
In addition, as an image reproducing apparatus that expands the compressed and encoded compressed image data, an inverse discrete cosine transform (I
Those based on (DCT) are often used.

FIG. 10 is a block diagram showing an example of the configuration of a conventional image reproducing apparatus conforming to the MPEG, and includes a header analyzing unit 101, a decoding unit 102, and an inverse quantization unit 10.
3, the IDCT means 104, the front frame unit 105,
Rear frame section 106, pre-prediction means 107, both prediction means 108, post-prediction means 109, video memory 110
And display means 111.

[0005] Header analysis means 101 reads image data having a hierarchical structure and analyzes the type of code and the like.
In MPEG, there are three types of I-pictures, which are intra-frame codes, P-pictures, which are inter-frame codes only in the forward direction, and B-pictures, which are bi-directional inter-frame codes.

If the analysis result of the header analysis means 101 is an I picture, the highly efficient variable-length Huffman code is decoded by the decoding means 102, and the decoded result is dequantized by the dequantization means 103. Further, the IDCT means 104 performs an inverse discrete cosine transform on the result of the inverse quantization to calculate the value of each pixel, and writes the calculated value of each pixel to the video memory 110.
The image expanded to 1 is displayed.

If the analysis result is a P-picture, the decoding means 102 decodes the highly efficient compressed variable-length Huffman code, and decodes the decoding result into an inverse quantization means 103.
And the IDCT means 104 performs inverse discrete cosine transform on the result of the inverse quantization to calculate the difference between the blocks. This difference and the previous frame extracted from the previous frame unit 105 by the previous prediction unit 107 are calculated. With the motion-compensated block therein, and the result of addition is stored in the video memory 11.
By writing 0, the expanded image is displayed on the display unit 111.

If the analysis result is a B picture, the highly efficient compressed variable-length Huffman code is decoded by the decoding means 102, and the decoded result is decoded by the inverse quantization means 103.
, And the IDCT means 104 performs an inverse discrete cosine transform on the result of the inverse quantization to calculate a difference between the blocks. The average value of the motion-compensated block in the previous frame and the subsequent frame extracted from the frame or the motion-compensated block in the post-frame extracted from the subsequent frame unit 106 by the post-prediction unit 109 is added, and the addition result is stored in the video memory 110. By writing, the expanded image is displayed on the display unit 111.

By the way, the at the image reproducing apparatus as described above, decrypt unit 102, an inverse quantization unit 103, I
Generally, the DCT means 104 and the like are configured using a CPU. However, since the amount of processing in each of the above-described units is very large, an image cannot be reproduced at a predetermined speed unless a high-speed CPU is used.

In order to enable reproduction at a predetermined speed even with a low-speed CPU, compressed image data obtained by compression-encoding reduced image data generated by thinning out some pixels in image data is sent to an image reproducing apparatus. Conventionally, an image reproducing apparatus performs an expansion process on input compressed and reduced image data and enlarges the expanded reduced image data to an original size. (For example, "Digital Communication Technology", Kimio Tanaka, 19
March 25, 1986 1st printing, issuance office Tokai University Press,
P61).

[0011]

According to the above-mentioned prior art, the processing amount of each means such as a decoding means, an inverse quantization means and an IDCT means is reduced, so that reproduction at a predetermined speed can be performed even with a low-speed CPU. Although this is possible, image data is reproduced based on reduced image data in which pixels have been thinned out, so that there is a problem in that image quality deteriorates.

[0012] Such a problem is caused by a low-performance low-speed CP.
There is no way to keep the playback speed of the image playback device using U at a constant playback speed. However, in the above-described conventional technology, in the image playback device using a high-performance, high-speed CPU, Quality will be degraded.

Therefore, an object of the present invention is to use a C
Regardless of the performance of PU, a certain playback speed can be guaranteed,
Another object of the present invention is to provide an image reproducing apparatus capable of obtaining high image quality when a CPU used has high performance.

[0014]

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a CPU performance measuring means for measuring the performance of addition / subtraction processing of a CPU in an image reproducing apparatus for decompressing compressed image data using a CPU. For restoring a portion of the image data that has been subjected to decimation, which is added to the compressed reduced image data obtained by compressing and encoding the reduced image data formed by thinning out some pixels from the image data. The CPU comprising: an additional information reading unit that determines whether to read the compression-encoded additional information based on a measurement result of the CPU performance measurement unit;
Expands the compressed / reduced image data and expands the additional information read by the additional information reading means.If the additional information reading means does not read the additional information, the expanding means When the reduced image data generated by expanding the compressed reduced image data is restored by enlarging the image data to the same size, and the additional information reading means reads the additional information, the CPU Is a method for restoring the image data based on reduced image data generated by expanding the compressed reduced image data and a result of expansion performed on the additional information by the CPU.

[0016]

[Function] C for decompressing the compressed and encoded compressed image data
The performance of the PU surplus processing is measured by the CPU performance measuring means. The additional information reading means reads the additional information when the performance of the addition / subtraction processing of the CPU measured by the CPU measuring means is higher and equal to a predetermined performance, and does not read the additional information when the performance is lower than the predetermined performance. . The CPU expands the compressed reduced image data and expands the additional information read by the additional information reading means. In the enlarging means, when the additional information reading means does not read the additional information, the CPU expands the reduced image data expanded by the CPU to the same size as the image data to restore the image data. Is read, the image data is restored based on the reduced image data expanded by the CPU and the expansion result performed on the additional information by the CPU.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an image reproducing apparatus according to the present invention, which is based on MPEG.

The image reproducing apparatus according to the present embodiment comprises a header analyzing means 1, an additional information reading means 2, a CPU performance measuring means 3, a decoding means 4, an inverse quantization means 5, an IDCT
It comprises a means 6, a pre-prediction means 7, both prediction means 8, a post-prediction means 9, a front frame section 10, a rear frame section 11, an enlarging means 12, a video memory 13, and a display means 14. Is done.

The CPU performance measuring means 3 when turning the image reproducing apparatus (at initial), decrypt unit 4, to measure the performance of the CPU for realizing the inverse quantization means 5, IDCT unit 6 and the like. FIG. 2 is a flowchart showing a processing example of the CPU performance measuring means 3. When the power is turned on, the CPU performance measuring means 3 first sets "0" to the counter C in step S201, and sets a timer in the next step S202. . Thereafter, the number of times that the addition / subtraction processing in step S203 can be performed within a certain time in the loop of steps S203 to S205 is counted using the counter C, and the count value Ct is determined by the CP.
U performance. Naturally, the count value Ct
Is larger, the performance of the CPU is higher.

The header analysis means 1 and the additional information reading means 2 receive image data having a hierarchical structure conforming to MPEG.

FIG. 3 is a diagram showing a hierarchical structure of image data conforming to MPEG. The uppermost layer is a video sequence, and one or more GOPs (Group Of POPs).
picture). A GOP is composed of one or more pictures, and one picture indicates one image. A picture is composed of one or more slices divided into arbitrary regions. A slice is composed of a plurality of macroblocks arranged in left-to-right and top-to-bottom order. Each macro block is 8 × 8
The block is composed of a total of six blocks including a block of luminance components (Y1, Y2, Y3, Y4) of pixels and a block of color difference components (Cb, Cr) of 8 × 8 pixels. A block of 8 × 8 pixels is the minimum unit of encoding.

FIG. 4 is a diagram showing a format of image data conforming to MPEG. MPEG image data is
Sequence header Seq, Gop header G, picture header Picture, slice header Slice
, Macro block header Macro, and block code Block.

The picture header Picture has a start code PicStart, a code TempRef indicating the display order, and a code Pic indicating the type of picture.
Code and a code UsrS indicating the existence of user data
start and user data UserData.

The user data UserData can be freely defined by the user. In this embodiment, the identifier "Custom" indicating that additional information has been added is provided.
, A flag cflg indicating the type of additional information, the number of divisions cnum indicating the number of divisions of the reduced image data, and a plurality of pieces of additional information Code1 to Code
eN is set.

The flag cflg indicating the type of additional information is
When only the least significant bit B0 is "1", the type of additional information is an I picture, and when only the next bit B1 is "1", the type of additional information is a P picture. When only the bit B2 is "1", it indicates that the type of the additional information is a B picture. When only the bit B3 is "1", the type of the additional information is a compression code indicating the difference between the picture data and the reduced image data. Indicates that the

FIG. 5 is a diagram for explaining additional information and picture data when the division number cnum = 4. The image data is divided into 2 × 2 pixel blocks B11, B12,..., And compressed reduced image data obtained by compressing and encoding reduced image data A formed by collecting upper left pixels in each of the blocks B11, B12. Data. Are compressed information of reduced image data B formed by collecting upper right pixels in each block B11, B12,..., And compressed information is compressed information of reduced image data C formed by collecting lower left pixels. The converted information is the additional information Code2, and the compressed information of the reduced image data D formed by collecting the lower right pixel is the additional information Code3. In the following description, it is assumed that the division number cnum = 4.

At the time of inputting image data, the header analysis means 1 analyzes the type of picture data, the type of additional information, and the like.

When inputting image data, the additional information reading means 2 determines that the additional information Code1 is present when the measurement result of the CPU performance measuring means 3 indicates that the performance of the CPU is sufficiently high, that is, when Ct ≧ 4α. , Code2, Code
e3 and reads them out sequentially to the decoding means 4,
After that, it instructs the header analysis means 1 to output the picture data. Here, α is a value determined by the number of divisions cnum, and indicates a value of CPU performance required for expanding one reduced image data divided by the number of divisions.
If the measurement result of the CPU performance measuring means 3 indicates that the performance of the CPU is low, that is, if 2α> Ct, the additional information is not read and the header analyzing means 1 is not read.
Is instructed to output picture data. Also, CP
If the measurement result of the U performance measuring means 3 indicates that the performance of the CPU is intermediate between the above two cases,
If α> Ct ≧ 2α, additional information Code1, Code
Only the additional information Code1 of e2 and Code3 is read and output to the decoding means 4, and thereafter, the header analysis means 1 is instructed to output picture data.

Now, for example, when the measurement result of the CPU performance measuring means 3 is Ct ≧ 4α, and the additional information Code1, Code2, Code3 is output from the additional information reading means 2, it is analyzed by the header analyzing means 1. The following processing is performed according to the type of the additional information.

When the picture is analyzed as an I picture:

The additional information Code1, Code2, and Code3 output from the additional information reading means 2 are decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is transmitted by the IDCT means 6. Are subjected to inverse discrete cosine transform, and the processing result of the IDCT means 6 (additional information Cod
The reduced image data B, C, and D obtained by expanding e1, Code2, and Code3 are passed to the enlargement unit 12.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

Upon receiving the reduced image data B corresponding to the additional information Code1, the enlarging means 12 determines the pixel values b0, b1, and b1 of each pixel in the reduced image data B as shown in FIG.
.. Are written in the upper right pixel position of each block when the video memory 13 is divided into 2 × 2 pixel blocks. Next, when the reduced image data C corresponding to the additional information Code2 is passed, the pixel value c of each pixel in the reduced image data C is obtained.
Write 0, c1,... To the lower left pixel position of each block in the video memory 13. Thereafter, when the reduced image data D corresponding to the additional information Code3 is passed, the pixel values d0, d1,... Of each pixel in the reduced image data D are stored in the video memory 1.
3 is written in the lower right pixel position of each block. Furthermore,
When the reduced image data A corresponding to the picture data is passed, the pixel values a0, a1,
.. Are written in the upper left pixel position of each block in the video memory 13. Thus, the expansion of one frame is completed, and the reproduced image is displayed on the display unit 14.

When the picture is analyzed as a P picture:

The additional information Code1, Code2, and Code3 output from the additional information reading means 2 are decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is obtained by the IDCT means 6. Is subjected to inverse discrete cosine transform, and the difference between the blocks is calculated. Further, the difference is added to the motion-compensated block in the previous frame corresponding to each of the reduced image data B, C, and D extracted from the previous frame unit 10 by the previous prediction unit 7, and the additional information Code1,
Code2, Code3 and corresponding reduced image data B,
Restore C and D. The restored reduced image data B,
C and D are passed to the enlarging means 12. The previous frame section 10 also stores a previous frame corresponding to the reduced image data A.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

The enlarging means 12 performs the processing shown in FIG. 6 on the received reduced image data A, B, C, and D.

When analyzed as a B picture:

The additional information Code1, Code2, and Code3 output from the additional information reading means 2 are decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is obtained by the IDCT means 6. Is subjected to inverse discrete cosine transform, and the difference between the blocks is calculated. Further, the difference and the two predicting means 8 are used by the front frame unit 10 and the rear frame unit 1.
1 or the average value of the motion-compensated blocks in the previous and subsequent frames of the reduced image data B, C, and D, or the subsequent frame of the reduced image data B, C, and D extracted from the subsequent frame unit 11 by the rear prediction unit 9. The motion-compensated blocks in the data are added, and additional information Code1, Code2, Code
The reduced image data B, C, and D corresponding to No. 3 are restored. The restored reduced image data is passed to the enlargement unit 12.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

The enlarging means 12 performs the processing shown in FIG. 6 on the received reduced image data A, B, C, and D.

When it is analyzed that the difference from the picture data is obtained by compressing and encoding:

The additional information Code1, Code2, and Code3 output from the additional information reading means 2 are decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is obtained by the IDCT means 6. And the result of processing by the IDCT means 6 (difference between reduced image data A and reduced image data B, difference between reduced image data A and reduced image data C, reduced image data A and reduced image data D Is passed to the enlarging means 12.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

Upon receiving the reduced image data A corresponding to the picture data, the enlarging means 12 performs, as shown in FIG.
Write the pixel values a0, a1,... Of each pixel in the reduced image data A to the upper left pixel position of each block in the video memory 13.

Next, the enlargement means 12 restores the reduced image data B by adding the additional information Code1 (the difference between the reduced image data A and the reduced image data B) to the reduced image data A, and Pixel value b of each pixel
Write 0, b1,... To the upper right pixel position of each block in the video memory 13.

After that, the enlargement means 12 restores the reduced image data C by adding the additional information Code 2 (the difference between the reduced image data A and the reduced image data C) to the reduced image data A, and Pixel value c of each pixel
0, c1,... Are written in the lower left pixel position of each block in the video memory 13.

Further, the enlarging means 12 outputs the reduced image data A
Is added to the additional information Code3 (the difference between the reduced image data A and the reduced image data D) to restore the reduced image data D, and the pixel value d of each pixel in the reduced image data D
, D2,... Are written in the lower right pixel position of each block in the video memory 13. Thus, the expansion of one frame is completed, and the reproduced image is displayed on the display unit 14.

For example, when the measurement result of the CPU performance measuring means 3 is 4α> Ct ≧ 2α and only the additional information Code1 is output from the additional information reading means 2,
The following processing is performed according to the type of the additional information analyzed by the header analysis means 1.

When the picture is analyzed as an I picture:

The additional information Code1 output from the additional information reading means 2 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is
The inverse discrete cosine transform is performed by the CT means 6, and the IDCT means 6
(Reduced image data B obtained by expanding the additional information Code1) is passed to the enlarging means 12.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

When the reduced image data B corresponding to the additional information Code1 is passed, the enlarging means 12 determines the pixel values b0, b0, and b0 of each pixel in the reduced image data B as shown in FIG. are written in the upper right pixel position of each block when the video memory 13 is divided into blocks of 2 × 2 pixels.

Next, when the reduced image data A corresponding to the picture data is passed, the pixels a0, a1,... Of each pixel in the reduced image data A are written to the upper left pixel position of each block in the video memory 13.

In the above processing, the video memory 13
Since no pixel value is written in the lower left and lower right pixel positions of each block in the middle, the enlarging means 12 is, for example, shown in FIG.
As shown in (A), the average value c0 ′, c of the upper and lower pixel values
1 ′,..., D0 ′, d1 ′,..., And writing them to the lower left and lower right pixel positions of each block, or
As shown in (B), the pixel values a0, a1, ..., b0, b1, ... at the upper left and upper right pixel positions of each block are written into the lower left and lower right pixel positions of each block. This gives 1
The expansion of the frame is completed, and the reproduced image is displayed on the display unit 14.

When the picture is analyzed as a P picture:

The additional information Code1 output from the additional information reading means 2 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is
The inverse discrete cosine transform is performed by the CT means 6, and the difference between the blocks is calculated. Further, the difference and the motion-compensated block in the previous frame corresponding to each reduced image data B extracted from the previous frame unit 10 by the previous prediction unit 7 are added to restore the reduced image data B corresponding to the additional information Code1. I do. The restored reduced image data B is supplied to the enlargement unit 12.
Passed to.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

The enlarging means 12 performs the processing shown in FIG. 7 on the received reduced image data A and B.

When analyzed as a B picture:

The additional information Code1 output from the additional information reading means 2 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is
The inverse discrete cosine transform is performed by the CT means 6, and the difference between the blocks is calculated. Further, the difference and the average value of the motion-compensated blocks in the front and rear frames of the reduced image data B extracted from the previous frame unit 10 and the rear frame unit 11 by both prediction units 8 or the rear prediction unit 9 And the motion-compensated block in the succeeding frame in the subsequent frame is added to restore the reduced image data B corresponding to the additional information Code1. The restored reduced image data B is passed to the enlargement means 12.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

The enlarging means 12 performs the processing shown in FIG. 7 on the received reduced image data A and B.

When it is analyzed that the difference from the picture data is obtained by compressing and encoding:

The additional information Code1 output from the additional information reading means 2 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is
The inverse discrete cosine transform is performed by the CT means 6, and the IDCT means 6
(The difference between the reduced image data A and the reduced image data B) is passed to the enlarging means 12.

Thereafter, the picture data corresponding to the reduced image data A is output from the header analysis means 1 which has received the instruction to output the picture data. The same processing as described above is performed on the picture data, and the reduced image data A obtained by expanding the picture data is passed to the enlargement unit 12.

Upon receiving the reduced image data A corresponding to the picture data, the enlarging means 12 determines the pixel value a0 of each pixel in the reduced image data A as shown in FIG. 7A or 7B. , A1,... Are written in the upper left pixel position of each block in the video memory 13.

Next, the enlarging means 12 restores the reduced image data B by adding the additional information Code 1 (the difference between the reduced image data A and the reduced image data B) to the reduced image data A, and Pixel value b of each pixel
Write 0, b1,... To the upper right pixel position of each block in the video memory 13.

Thereafter, as shown in FIG. 7 (A) or (B), the enlarging means 12 places the average value of the pixel values of the upper and lower pixels at the lower left and lower right pixel positions of each block of the video memory 13. Write the pixel value of the upper pixel. This allows
When the expansion for one frame is completed, the reproduced image is displayed on the display unit 14.
Will be displayed.

For example, if the measurement result of the CPU performance measuring means 3 is 2α> Ct and no additional information is output from the additional information reading means 2, the type of the additional information analyzed by the header analyzing means 1 The following operation is performed in accordance with.

When the picture is analyzed as an I picture:

The picture data corresponding to the reduced image data A output from the header analysis means 1 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is obtained by the IDCT means. In step 6, the inverse discrete cosine transform is performed, and the processing result of the IDCT unit 6 (reduced image data A obtained by expanding the picture data) is passed to the enlarging unit 12.

Upon receiving the reduced image data A corresponding to the picture data, the enlarging means 12 sets the pixel value a0 of each pixel in the reduced image data A as shown in FIG. 8A or 8B. , A1,... Are written in the upper left pixel position of each block when the video memory 13 is divided into 2 × 2 pixel blocks.

In the above processing, the video memory 13
Since no pixel value is written in the upper right, lower left, and lower right pixel positions of each block in the middle, the enlargement unit 12
As shown in FIG. 8A, the average value b0 ′, b1 ′ of the pixel values of the left and right pixels at the upper right pixel position of each block.
.., And at the lower left and lower right pixel positions of each block, average values c0 ′, c1 ′,.
0 ′, d1 ′,...
Write to lower left and lower right pixel positions, or
As shown in (B), the pixel values a0, a1,... At the upper left pixel position of each block are written in the upper right, lower left, lower right pixel positions. Thus, the expansion of one frame is completed, and the reproduced image is displayed on the display unit 14.

When the picture is analyzed as a P picture:

The picture data corresponding to the reduced image data A output from the header analysis means 1 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is obtained by the IDCT means. In step 6, an inverse discrete cosine transform is performed to calculate a block difference. Further, the difference and the motion-compensated block in the previous frame corresponding to the reduced image data A extracted from the previous frame unit 10 by the previous prediction unit 7 are added to restore the reduced image data A. The restored reduced image data A is passed to the enlargement means 12.

The enlarging means 12 performs the processing shown in FIG. 7A or 7B on the received reduced image data A.

When analyzed as a B picture:

The picture data corresponding to the reduced image data A output from the header analysis means 1 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is obtained by the IDCT means. In step 6, an inverse discrete cosine transform is performed to calculate a block difference. Further, the difference and the average value of the motion-compensated blocks in the front and rear frames of the reduced image data A extracted from the previous frame unit 10 and the rear frame unit 11 by the both prediction units 8 or the rear prediction unit 9 outputs The reduced image data A is restored by adding the motion-compensated blocks in the frame of the reduced image data A extracted from the frame. The restored reduced image data A is passed to the enlargement means 12.

The enlarging means 12 performs the processing shown in FIG. 8A or 8B on the transferred reduced image data A.

When it is analyzed that the difference from the picture data is obtained by compressing and encoding:

The picture data corresponding to the reduced image data A output from the header analysis means 1 is decoded by the decoding means 4, the decoding result is inversely quantized by the inverse quantization means 5, and the inverse quantization result is obtained by the IDCT means. In step 6, the inverse discrete cosine transform is performed, and the processing result (reduced image data A) of the IDCT unit 6 is passed to the enlargement unit 12.

The enlarging means 12 performs the processing shown in FIG. 8A or 8B on the received reduced image data A.

In the above-described embodiment, when the measurement result of the CPU performance measuring means 3 satisfies Ct ≧ 4α, the additional information reading means 2 reads all the additional information Code1, Code2, Code3, and 4α> Ct. When ≧ 2α, the additional information reading unit 2 reads only some of the additional information Code1, and when 2α> Ct, the additional information is not read. However, when Ct ≧ 4α, all the additional information Code1 is not read. , Code2, and Code3, and in other cases, that is, in the case of Ct <4α, the additional information may not be read. Also,
In the embodiment, the additional information is added to the user data of the picture header. However, the additional information is added to the extension data or user data defined as an extension area of any one of the sequence header, the GOP header, the picture header, and the slice header. You may make it add. In the above-described embodiment, the image data enlarged by the enlarging means 12 is written in the video memory 13 for display. However, the image data may be stored in a hard disk or a memory.

FIG. 9 is a block diagram showing an example of the configuration of an image compression apparatus for generating image data in a format conforming to MPEG as shown in FIG. 4, wherein an image file 21 storing image data and a reduced image data Generating means 22
4, a difference calculating unit 23, an encoding unit 24 based on MPEG, a header information adding unit 25, a compression code file 26 storing image data in a format as shown in FIG. 4, and an input unit such as a keyboard. 27.

When generating image data in a format conforming to MPEG as shown in FIG. 4, the user inputs an instruction as to whether or not user data is to be obtained by compressing and encoding the difference from picture data. 27, and the number of divisions (4 in this example) indicating how many pieces of reduced image data are to be divided into the image data.
Input from 7.

First, a description will be given of an operation in the case where it is not instructed by the user to convert the difference between the picture data and the picture data into user data by compression coding.

The reduced image data generating means 22 extracts image data from the image file 21 frame by frame, and performs the following processing on the extracted image data.

First, as shown in FIG.
The image data for one frame extracted from 1 is divided into 2 × 2 pixel blocks B11, B12,..., And the upper left pixel in each of the blocks B11, B12,. The reduced image data A is generated, and the generated reduced image data A is output to the encoding unit 24. When outputting the reduced image data A, the reduced image data generating unit 22 instructs the header information adding unit 25 to use the compression code corresponding to the reduced image data A output from the encoding unit 24 as picture data. I do.

Thereafter, the reduced image data generating means 22
The reduced image data B, C, and D in which the image data is reduced to 1/4 by sequentially collecting the upper right pixel, the lower left pixel, and the lower right pixel in the blocks B11, B12,. The image data B, C, and D are sequentially output to the encoding unit 24. When outputting the reduced image data B, C, and D, the reduced image data generating unit 22 instructs the header information adding unit 25 to use the compression code output from the encoding unit 24 as user data.

When the reduced image data A is output from the reduced image data generation unit 22, the encoding unit 24 compression-encodes the reduced image data A and outputs it to the header information adding unit 25. Further, the encoding means 24 calculates a motion vector, a macroblock type,
It also outputs quantization characteristic designation information, quantization transform coefficients, and the like.

The header information adding means 25 includes the encoding means 2
4 outputs the compressed code of the reduced image data A as the picture data and the flag C of the additional information.
custom, various information output from the encoding unit 24, the number of divisions input from the input unit 27, and the like are added to the picture data.

The encoding means 24 performs the same processing when the reduced image data B, C, and D are output from the reduced image data generating means 22.

The header information adding means 25 includes the encoding means 2
4 outputs compressed codes corresponding to reduced image data B, C, and D, as shown in FIG.
It is assumed that de1, Code2, and Code3.

When image data having a format as shown in FIG. 4 is generated, it is stored in the compression code file 26.

Next, a description will be given of the operation in the case where the user instructs to convert the difference between the picture data and the picture data into user data.

First, as shown in FIG.
The image data for one frame extracted from 1 is divided into 2 × 2 pixel blocks B11, B12,..., And the upper left pixel in each of the blocks B11, B12,. The reduced image data A is generated, and the generated reduced image data A is output to the encoding unit 24 and the difference calculation unit 23. When outputting the reduced image data A, the reduced image data generating unit 22 instructs the header information adding unit 25 to use the compression code corresponding to the reduced image data A output from the encoding unit 24 as picture data. I do.

Thereafter, the reduced image data generating means 22
The reduced image data B, C, and D in which the image data is reduced to 1/4 by sequentially collecting the upper right pixel, the lower left pixel, and the lower right pixel in the blocks B11, B12,. The image data B, C, and D are sequentially output to the difference calculator 23.

When the reduced image data A is output from the reduced image data generating unit 22, the encoding unit 24 compression-encodes the reduced image data A and outputs it to the header information adding unit 25. Further, the encoding means 24 calculates a motion vector, a macroblock type,
It also outputs quantization characteristic designation information, quantization transform coefficients, and the like.

The header information adding means 25 includes the encoding means 2
When the compressed code of the reduced image data A is output from 4, it is used as picture data, and various information output from the encoding means 24 and the number of divisions input from the input means 27 are added to the picture data. .

When the reduced image data A, B, C, and D are output from the reduced image data generator 22, the difference calculator 23 calculates the difference between the reduced image data A and the reduced image data B and the reduced image data. A and the difference between the reduced image data C,
The difference between the reduced image data A and the reduced image data D is calculated, and the calculated difference is sequentially output to the encoding unit 24. When outputting the difference, the difference calculation unit 23 instructs the header information addition unit 25 to use the compression code output from the encoding unit 24 as user data. When calculating the above difference, once for each reduced image data,
DCT, quantization, compression, then inverse quantization, IDCT
It is preferable to take a difference between the reduced image data expanded by performing the above.

The encoding means 24 performs the same processing when the difference between the reduced image data A and the reduced image data B, C, D is output from the difference calculating means 23.

[0104] The header information adding means 25 includes the encoding means 2
When the compressed code corresponding to the difference between the reduced image data A and the reduced image data B, C, and D is output from No. 4, these are set as additional information Code1, Code2, and Code3.

When image data having a format as shown in FIG. 4 is generated, it is stored in the compression code file 26.

[0106]

As described above, according to the present invention, the performance of the addition / subtraction processing of the CPU for expanding the compressed image data is determined by the CPU.
Measured by the performance measuring means. If the performance of the CPU addition / subtraction processing is low, the image is restored using only the compressed and reduced image data. If the CPU addition / subtraction processing performance is high, the compression / reduction is performed. Since the image is restored using the image data and the additional information, the CPU used
Irrespective of the performance of the addition / subtraction processing , a constant reproduction speed can be guaranteed, and high image quality can be obtained when the CPU used has high performance.

Further, according to the present invention, based on the measurement result of the CPU performance measuring means, the image is restored using only the compressed reduced image data or the image is restored using the compressed reduced image data and a part of the additional information. or to, since the divided cut or to restore an image using the compressed reduced image data and all of the additional information, regardless of sex <br/> ability subtraction modulo processing of CPU used, a constant There is an effect that the reproduction speed can be guaranteed and the best image quality according to the performance of the addition / subtraction processing of the CPU being used can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing example of a CPU performance measuring means 3;

FIG. 3 is a diagram showing a hierarchical structure of image data conforming to MPEG.

FIG. 4 is a diagram showing a format of image data conforming to MPEG.

FIG. 5 is a diagram for explaining picture data and additional information.

FIG. 6 is a diagram for explaining a processing example of an enlarging unit 12;

FIG. 7 is a diagram for explaining a processing example of the enlarging means 12;

FIG. 8 is a diagram for explaining a processing example of the enlarging means 12;

FIG. 9 is a block diagram illustrating a configuration example of an image compression device.

FIG. 10 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Header analysis means 2 ... Additional information reading means 3 ... CPU performance measurement means 4 ... Decoding means 5 ... Inverse quantization means 6 ... IDCT means 7 ... Pre-prediction means 8 ... Both prediction means 9 ... Post-prediction means 10 ... Before Frame part 11 ... Back frame part 12 ... Enlargement means 13 ... Video memory 14 ... Display means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 7/24 G06F 15/66 330D

Claims (4)

(57) [Claims] 1. A compression-encoded compressed image data is represented by a CP
A CPU performance measuring means for measuring the performance of addition / subtraction processing of the CPU in the image reproducing apparatus which expands using U, and compression-encodes reduced image data constituted by thinning out some pixels from the image data Whether or not to read the compression-encoded additional information for restoring the thinned-out portion in the image data, which is added to the compressed and reduced image data, is determined by the measurement result of the CPU performance measurement unit. The additional information reading means for determining, and the enlarging means, wherein the CPU expands the compressed reduced image data and expands the additional information read by the additional information reading means, If the reading means does not read the additional information, the CPU generates a reduced image generated by expanding the compressed reduced image data. The image data is restored by enlarging the data to the same size as the image data, and when the additional information reading means reads the additional information, the CPU generates the image data by expanding the compressed reduced image data. An image reproducing apparatus for restoring the image data based on the reduced image data thus obtained and a result of expansion performed on the additional information by the CPU. 2. One of a plurality of reduced image data constituted by collecting pixels having the same arrangement position in each block when the image data is divided into a plurality of blocks.
2. The compression-encoded image data of one of the plurality of reduced image data, and the compression-encoded remaining image data of the plurality of reduced image data is used as the additional information. Image playback device. 3. The apparatus according to claim 2, wherein the additional information reading unit includes
Adjustable surplus processing of CPU measured by U performance measuring means
When the performance of processing is higher than the predetermined performance, etc.
2. The image reproducing apparatus according to claim 1, wherein the additional information is read when it is appropriate, and the additional information is not read when the performance is lower than a predetermined performance. 4. An image reproducing apparatus for decompressing compressed and encoded image data using a CPU, a CPU performance measuring means for measuring the performance of the addition / subtraction processing of the CPU, and The plurality of reduced images which are added to compressed reduced image data obtained by compressing and encoding one of a plurality of reduced image data formed by collecting pixels having the same arrangement position in each block when divided. The additional information obtained by compressing and encoding the remaining reduced image data in the data is obtained by the CPU performance measuring means.
The performance of the addition / subtraction processing of the CPU is a predetermined
If the performance is higher than and equal to 1, read all,
A second predetermined performance lower than the first performance;
If it is lower, it is not read at all and is lower than the first performance.
And higher than the second performance and the second performance
If it is equal to, additional information reading means for reading only a part , and enlargement means, the CPU expands the compressed reduced image data and expands the additional information read by the additional information reading means, The enlargement unit enlarges the reduced image data generated by the CPU by expanding the compressed reduced image data to the same size when the additional information reading unit does not read the additional information. When the additional information reading means reads a part of the additional information, the CP
U restores the image data based on reduced image data generated by decompressing the compressed reduced image data and the decompression result performed by the CPU on some additional information read by the additional information reading means. If the additional information reading means has read all of the additional information, the reduced image data generated by decompressing the compressed reduced image data by the CPU and all of the additional information read by the CPU by the CPU are read. An image reproducing apparatus for restoring the image data based on a result of expansion performed on additional information.