Method and apparatus for displaying images with compression mechanism

• US 7,570,819 B2
• Filed: 01/28/2005
• Issued: 08/04/2009
• Est. Priority Date: 01/28/2005
• Status: Active Grant

• Current Assignee: Taiwan Imaging Tek Corporation
• Original Assignee: Taiwan Imaging Tek Corporation
• Inventors: Sung, Chih-Ta Star, Lan, Yin-Chun
• Primary Examiner(s): Do; Anh Hong
• Application Number:
  US11/044,255
• Publication Number:
  US 20060171596A1
• Time in Patent Office: 1,649 Days
• Field of Search: 382/232, 382/233, 382/244, 382/245, 382/246, 382/247, 382/166, 382/241, 382/197, 382/298, 345/501, 345/572, 345/537, 345/556, 345/560, 709/236, 712/1, 712/200, 358/450, 358/452, 375/E7.088, 375/E7.133
• US Class Current: 382/232
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component

Abstract

A codec device is disposed in a display control device for instantly supplying decompressed image data to manipulating devices in the display control chip. Reference images are stored in compressed format after instantly compressed by the codec device. In addition, MSB portions and LSB portions are separately compressed for gaining higher compression ratio. Predication of the pixel value is also modified in variable length coding. On-chip line buffer is also applied with the instant compression mechanism. Fixed compression ratio is predetermined to actually downsize the chip design for the worst case.

Claims

1. An apparatus for compressing a raw image, comprising:

a device partitioning a raw image into a plurality of lines with each line having a plurality of blocks and each block having a plurality of pixels;

a device performing a pre-processing on the raw image with a frame codec device to generate an intermediate data that has higher resemblance than the raw image; and

an image compression device reducing the data amount of the pre-processed raw image.

2. The apparatus of claim 1, wherein in the pre-processing, a first color attribute of each pixel is subtracted by a second color attribute of each pixel when generating the intermediate data.

3. The apparatus of claim 1, wherein in the pre-processing, differential values among adjacent pixels are used to generate the intermediate data.

4. The apparatus of claim 1, wherein in the pre-processing, differential values among adjacent pixels are used to generate the intermediate data.

5. The apparatus of claim 1, wherein the image compression codec device has a mechanism of separating MSB portions and LSB portions of the intermediate data for compression during compressing the raw image.

6. The apparatus of claim 5, wherein the image compression codec device determines whether to separate the MSB portions and the LSB portions of the intermediate data by checking the variance of the MSB portions.

7. The apparatus of claim 5, wherein units in the LSB portions are regrouped based on associated units in the MSB portions for compression.

8. The apparatus of claim 5, wherein a number of units of the LSB portions are truncated depending on a compression ratio of associated MSB portions to achieve a predetermined total compression ratio of the LSB portions and the MSB portions.

9. The apparatus of claim 8, wherein a carry-over operation to the MSB portions associated to the LSB portions is performed, where the LSB portions have units to be truncated if units of LSB portions to be truncated exceed a carry-over threshold.

10. The apparatus of claim 8, wherein the truncated units of each LSB portions are selected in a rotated order.

11. The apparatus of claim 1, wherein a total compression ratio of the raw image is predetermined and during the compression, a compression ratio of each block of the raw image is adapted dynamically to achieve the total predetermined compression ratio of the raw image.

12. The apparatus of claim 11, the raw image is divided into a plurality of areas and in each area, a referencing line in each area is selected to be compressed under a lossless compression means and compression ratios of lines other than the reference line in each area are adapted to make each area achieve the final total compression ratio under a lossy compression that refers to the compression result of the referencing line with lossless compression mean.

13. The apparatus of claim 1, further comprising a line compression codec device and at least one line buffer device, wherein the line compression codec device instantly compresses and decompresses one line pixels used by the manipulating device.

14. The apparatus of claim 13, a compression ratio of each block of the line data refers to the data amount of an associated block of another line data compressed by the line codec device previously.

15. A device of compressing a raw image, comprising:

a device performs a pre-processing on the raw image to generate an intermediate data that has higher resemblance than the raw image;

a storage device temporarily saving the intermediate data of a plurality of lines with each line having a plurality of units associated to pixels of the raw image;

a counting device calculating a weighted summation of a plurality of units of the intermediate data adjacent to an unit to be compressed; and

a coding engine calculating a quotient and a remainder so that the unit to be compressed equals to the quotient multiplies a divider plus the remainder; and

the quotient and the remainder are used for compression.

16. The apparatus of claim 15, wherein the divider is calculated by the following function:

Mn=(Mn−

1+Dn)/2

where Dn is the value of an unit of the intermediate data indexed with n, and Mn is the associated divider of Dn.

17. The apparatus of claim 15, wherein the image frame compression codec device performs a pre-processing on the raw image to generate an intermediate data that has higher resemblance than the raw image;

the intermediate data has a plurality of lines, each line has a plurality of units associated to pixels of the raw image;

the image frame compression codec device calculates a quotient and a remainder so that the unit to be compressed equals to the quotient multiplies a divider plus the remainder, and the quotient and the remainder are used for compression;

the divider is determined as the smaller value of the left unit and the top unit if a target unit is larger then the left unit and the top unit, determined as the larger value of the left unit and the top unit if the target unit is smaller than the left unit and the top unit, and determined as the left unit plus the top pixel minus an average of the left-top unit and the right-top unit if the target unit, the top unit and the left unit do not satisfy the above two situations.

18. The apparatus of claim 15, wherein the frame codec device rotates the raw image if the raw image has higher resemblance in Y-axis than in X-axis.

19. A method for compressing image data, comprising:

using a traversing device for traversing the image data line by line and pixel by pixel, wherein the pixel being currently traversed is a target pixel;

using a device for determining a predicated value of the target pixel by reference to a left pixel, a left-top pixel, a top pixel, and a right-top pixel those are adjacent to the target pixel; and

using a decomposing device for decomposing the target pixel as a predication polynomial of the predicated value and at least two parameters; and

utilizing the parameters for coding the target pixel.

20. The method of claim 19, wherein the predication polynomial is:

D=Y×

M+R , where M is the predicated value, Y and R are the two parameters.

21. The method of claim 19, wherein the predicated value is determined as the smaller value of the left pixel and the top pixel if the target pixel is larger than the left pixel and the top pixel, determined as the larger value of the left pixel and the top pixel if the target pixel is smaller than the left pixel and the top pixel, and determined as the left pixel plus the top pixel minus an average of the left-top pixel and the right-top pixel if the target pixel, the top pixel and the left pixel do not satisfy the above two situations.