Partial image decompression of a tiled image

• US 6,897,858 B1
• Filed: 02/16/2000
• Issued: 05/24/2005
• Est. Priority Date: 02/16/2000
• Status: Expired due to Term

• Current Assignee: DigiMedia Tech, LLC (IP Investments Group LLC)
• Original Assignee: Enroute Incorporated
• Inventors: Lavin, Andrew J., Hashimoto, Roy T.
• Primary Examiner(s): HARRISON, CHANTE E
• Application Number:
  US09/505,352
• Time in Patent Office: 1,924 Days
• Field of Search: 345/423, 345/420, 345/419, 345/582, 345/555
• US Class Current: 345/419
• CPC Class Codes: G06T 9/001 Model-based coding, e.g. wire frame
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

A decompression unit is configured to partially decompress a compressed image formed by compressed tiles. Each compressed tiles correspond to a tile of the uncompressed image. The decompression unit selects a subset of relevant tiles, which are visible in a view window or a view frustum. Specifically, the decompression unit includes a tile selector to select the relevant tile and a tile decompressor to decompress the relevant tiles. By decompressing only a subset of the compressed tiles, the decompression unit reduces the processing time required to generate the contents of the view window.

Claims

1. A method for partially decompressing a compressed image having a plurality of compressed tiles, wherein each compressed tile corresponds to a tile, wherein each tile has a plurality of vertices, the method comprising:

classifying each vertex of each tile by;

determining whether each vertex is above a view frustum;

determining whether each vertex is below the view frustum;

determining whether each vertex is the right of the view frustum; and

determining whether each vertex is to the left of the view frustum;

setting a first bit of a bit code of a vertex when the vertex is to the left of the view frustum;

setting a second bit of the bit code of the vertex when the vertex is to the right of the view frustum;

setting a third bit of the bit code of the vertex when the vertex is below the view frustum; and

setting a fourth bit of the bit code of a vertex when the vertex is above the view frustum;

selecting a plurality of relevant tiles by;

selecting each tile as a relevant tile when a bitwise logic AND of a bit-code of a first vertex of a tile with a bit-code of a second vertex of the tile is equal to zero, wherein said first vertex and said vertex are adjacent vertices; and

selecting each tile as a relevant tile when a bitwise XOR of the bit-code the first vertex with a bit-code of a first opposite vertex is equal to 1111b and a bitwise XOR of the bit-code of the second vertex with a bit-code of a second opposite vertex is equal to 1111b;

retrieving a compressed tile corresponding to each relevant tile thereby forming a plurality of relevant compressed tiles; and

decompressing each of the relevant compressed tile.

2. The method of claim 1, wherein selecting a plurality of relevant tiles comprises:

selecting each tile that encompasses the view frustum;

selecting each tile contained within the view frustum; and

selecting each tile having at least one side crossing a side of the view frustum.

3. The method of claim 1, wherein selecting a plurality of relevant tiles comprises:

selecting each tile that encompasses a view window;

selecting each tile contained within the view window; and

selecting each tile having at least one side crossing a side of the view window.

4. The method of claim 1, wherein classifying each vertex of each tile further comprises:

determining whether each vertex is above a view window;

determining whether each vertex is below the view window;

determining whether each vertex is to the right of the view window; and

determining whether each vertex is to the left of the view window.

5. A decompression unit for decompressing a compressed image having a plurality of compressed tiles wherein each compressed tile corresponds to a tile and each tile has a plurality of vertices, the decompression unit comprising:

a tile vertex classifier coupled to the tile selector and configured to assign a bit code to the vertices of each tile, wherein the tile vertex classifier is configured to;

set a first bit of a bit code of a vertex when the vertex is to the left of a view window;

set a second bit of the bit code of the vertex when the vertex is to the right of the view window;

set a third bit of the bit code of the view window;

set a third bit of the bit code of the vertex when the vertex is below the view window; and

set a fourth bit of the bit code of a vortex when the vertex is above the view window;

a tile selector configured to receive the compressed image and to select a plurality of relevant tiles, by;

selecting each tile as a relevant tile when a bitwise logic AND of a bit-code of a first vertex of a tile with a bit-code of a second vertex of the tile is equal to zero, wherein said first vertex and said second vertex are adjacent vertices; and

selecting each tile as a relevant tile when a bitwise XOR of the bit-code the first vertex with a bit-code of a first opposite vertex is equal to 1111b and a bitwise XOR of the bit-code of the second vertex with a bit-code of a second opposite vertex is equal to 1111b; and

a tile decompressor coupled to the tile selector and configured to decompress each compressed tile corresponding to one of the relevant tiles.

6. The decompression unit of claim 5, wherein said tile selector uses the view window to select the plurality of relevant tiles.

7. The decompression unit of claim 6, wherein the tile selector is configured to select a tile as relevant when the tile is visible in the view window.

8. The decompression unit of claim 6, wherein the tile selector is configured to select a tile as relevant when the tile is visible in a view frustum of the view window.

9. The decompression unit of claim 5, wherein the tile vertex classifier is configured to determine if a vertex is above, below, to the left of, to the right of, or within a view window.

10. The decompression unit of claim 5, wherein the tile vertex classifier is configured to determine if a vertex is above, below, to the left of, to the right of, or within a view frustum of the view window.