Device and method for decompressing compressed video image

• US 6,205,251 B1
• Filed: 12/30/1997
• Issued: 03/20/2001
• Est. Priority Date: 11/06/1997
• Status: Expired due to Term

• Current Assignee: Winbond Electronics Corporation
• Original Assignee: Winbond Electronics Corporation
• Inventors: Hsieh, Tsung-Hsien, Hsu, Rong-Fu
• Primary Examiner(s): MEHTA, BHAVESH M
• Application Number:
  US09/000,861
• Time in Patent Office: 1,176 Days
• Field of Search: 382/246, 382/233, 382/298, 358/427, 358/261.1, 348/395
• US Class Current: 382/233
• CPC Class Codes: G06T 3/40 Scaling of whole images or parts thereof, e.g. expanding or contracting
• CPC Class Codes: G06T 9/005 Statistical coding, e.g. Huffman, run length coding

Abstract

A method and device for decompressing a compressed video image and capable of enlarging or contracting the image at the same time. The method utilizes an enhancement/contraction pre-processor to perform enlargement or contraction processing on the compressed data in the vertical direction. Then, at a later stage, an enhancement/contraction post-processor is used to perform enlargement or contraction processing on the decompressed data in the horizontal direction. By dividing the whole video image into a number of rows and dealing with each row sequentially, memory for storing a single row of video data is only required. Therefore, a whole image can be decompressed without using large amount of memory for storing the decompressed data; a large amount of memory is saved.

Claims

1. A device for decompressing compressed image data that has a line-end-code and is capable of being enlarged or contracted according to a prescribed ratio, comprising:

an enlargement/contraction pre-processor for receiving compressed image data and sending out a row control signal and a row compressed data according to the line-end-code and the enlargement/contraction ratio;

a compressed data buffer coupled to the enlargement/contraction pre-processor for processing the incoming row compressed data following the instructions from the row control signal, and then sending out duplicated, eliminated or unchanged row compressed data thereafter;

a variable length decoder coupled to the compressed data buffer for receiving the row compressed data, decompressing the row compressed data to form a row image data and then sending out the row image data;

a decompressed data buffer coupled to the variable length decoder for temporary storage of the row image data; and

an enlargement/contraction post-processor coupled to the decompressed data buffer for receiving a whole line of the row image data, and then sending out after the whole line of the row image data is enlarged or contracted accordingly to the enlargement/contraction ratio.

2. The device of claim 1, wherein the enlargement/contraction pre-processor further comprises:

a line-end-code searcher for checking out the line-end-code in the row compressed data, sending out the line-end-code and then sending out the row compressed data to the compressed data buffer;

a row counter coupled to the line-end-code searcher for receiving the line-end-code, and sending out row number data after computation; and

an enlargement/contraction pre-processing controller coupled to the row counter for receiving the row number data, and then sending out the row control signal representing actions to duplicate, eliminate or do nothing according to the enlargement/contraction ratio.

3. The device of claim 2, wherein when the enlargement/contraction ratio is for enlargement, then the row compressed data will either be duplicated or remain unchanged and then sent out.

4. The device of claim 2, wherein when the enlargement/contraction ratio is for contraction, then the row compressed data will either be eliminated or remain unchanged and then sent out.

5. The device of claim 1, wherein the decompressed data buffer is fabricated using static random access memory.

6. The device of claim 1, wherein the decompressed data buffer need to store one row of image data only.

7. A method for decompressing compressed image data, comprising the steps of:

providing a compressed image data having a line-end-code in it;

sending out a row control signal and a row compressed data according to the line-end-code of the compressed image data and an enlargement/contraction ratio;

processing the row compressed data by either duplicating, eliminating or doing nothing according to the row control signal received;

decompressing the row compressed data to get a row image data;

enlarging or contracting a whole line of the row image data according to the enlargement/contraction ratio;

repeating the above steps until the compressed data for the whole image is decompressed and the process of enlarging or contracting is completed.

8. The method of claim 7, wherein the step of sending out a row control signal and a row compressed data according to the line-end-code of the compressed image data and an enlargement/contraction ratio further includes the substeps of:

checking out the line-end-code from the row compressed data and then sending out the row compressed data and the line-end-code;

sending out row number data after computing the line-end-code; and

sending out control signals that represent actions either to duplicate, eliminate or do nothing according to a computation involving the row number data and the enlargement/contraction ratio.

9. The method of claim 8, wherein when the enlargement/contraction ratio is for enlargement, then the row compressed data will either be duplicated or remain unchanged and then sent out depending on the row control signal.

10. The method of claim 8, wherein when the enlargement/contraction ratio is for contraction, then the row compressed data will either be eliminated or remain unchanged and then sent out depending on the row control signal.