# US 2014/0192075 A1 · Adaptive Lossy Framebuffer Compression with Controllable Error Rate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192075 A1 - Document ID: US20140192075A1 - Status: Published application - Kind: A1 - Application number: 13/729,841 - Filed: 2012-12-28 - Published: 2014-07-10 - Earliest claimed: 2012-12-28 - Assignees: Think Silicon SA - Inventors: Iakovos Stamoulis; Georgios Keramidas; George Sidiropoulos - Web page: https://patentgrep.com/patent/US20140192075A1 ## CPC - G09G 5/395: Arrangements specially adapted for transferring the contents of the bit-mapped memory to the screen (G09G5/399 takes precedence) - G06T 11/40: Filling planar surfaces by adding surface attributes, e.g. adding colours or textures - G09G 5/393: Arrangements for updating the contents of the bit-mapped memory - G09G 3/2092: {Details of a display terminals using a flat panel, the details relating to the control arrangement of the display terminal and to the interfaces thereto (suitable for both CRT and flat panel G09G5/003; specific for a CRT G09G1/165)} - G09G 2350/00: Solving problems of bandwidth in display systems - G09G 2360/12: Frame memory handling - G09G 2360/122: Tiling - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract The device and method described in this application relate generally to graphics processing systems utilizing the tile based rendering technique and more specifically relate to the processing of the framebuffer data in graphics processing applications. The present invention discloses techniques to reduce the bandwidth needed to access the color data stored in the framebuffer. A method for adaptive lossy delta based compression of color data is disclosed. The error rate, that is the amount of color data lost during the lossy compression process, is controlled by various parameters of the rendered tiles produced by the graphics processing system. The compression process is driven by a dedicated unit which enables informed compression decisions with controllable error rate so as the output color data can be reliably decompressed to produce the original color data with minimal or no errors. ## Claims ### Claim 1 A device for color framebuffer tiled storage and control comprising of: means to receive fragments streams from a rendering graphics processing logic; a color blending unit; memory to hold a plurality of image fragments of at least two tiles; a sampling unit with means to calculate and store color deltas; a framebuffer update unit with integrated update history unit and comparison unit; a delta compression and decompression unit with color reduction logic; means to read and write tile metadata from external memory storage; means to transfer stored fragments to external memory storage. ### Claim 2 (depends on 1) The device of claim 1 where the compression unit is configured to perform lossless compression on tile color values. ### Claim 3 (depends on 1) The device of claim 1 where the compression unit is configured to perform lossy compression on tile color values as a function of the tile update rate. ### Claim 4 (depends on 1) The device of claim 1 where the compression unit is configured to perform lossy compression on tile color values as a function of user requirements. ### Claim 5 (depends on 1) The device of claim 1 where the compression unit is configured to perform lossy compression on tile color values as a function of the current system power state. ### Claim 6 (depends on 1) The device of claim 1 where the compression unit is configured to perform lossy compression on tile color values as a function of external lighting conditions. ### Claim 7 (depends on 2, 3, 4, 5, 6) The device as in any one of claims 2, 3, 4, 5 and 6 in which additional compression is performed using run-length encoding. ### Claim 8 (depends on 1) The device of claim 1 where the color sampling unit captures the color distribution of the tile colour values in compact way. ### Claim 9 (depends on 1) The device of claim 1 where the framebuffer update unit calculates the refresh rate on a tile-by-tile basis and encodes the refresh rate in an appropriate format in a storage memory. ### Claim 10 (depends on 1) The device of claim 1 where the compression unit that stores appropriate tile metadata consisting of information captured by the sampling unit; information captured by the framebuffer update unit; information required to decompressed the data comprising of reference pixel data and compression options data. ### Claim 11 A method of accessing compressed tiled frame buffer data comprising: receiving a new fragment to be accessed; blending a new fragment with existing fragments; storing a fragment to a local memory; calculating fragment channel distances from a reference value; encoding the distances as an array of numerical differences in ascending fashion; fetching metadata tile information from external memory; defining specific error thresholds based on tile characteristics; evaluating maximum acceptable error rate for a given compression level; compressing the tile region using delta compression; storing the compressed tile to an external memory. ### Claim 12 (depends on 11) The method of claim 11 where the compression process is configured to perform lossless compression on tile color values. ### Claim 13 (depends on 11) The method of claim 11 where the compression process is configured to perform lossy compression on tile color values as a function of the tile update rate. ### Claim 14 (depends on 11) The method of claim 11 where the compression process is configured to perform lossy compression on tile color values as a function of user requirements. ### Claim 15 (depends on 11) The method of claim 11 where the compression process is configured to perform lossy compression on tile color values as a function of the current system power state. ### Claim 16 (depends on 11) The method of claim 11 where the compression process is configured to perform lossy compression on tile color values as a function of external lighting conditions. ### Claim 17 (depends on 12, 13, 14, 15, 16) The method as in any one of claims 12, 13, 14, 15 and 16 in which additional compression processing is performed using run-length encoding. ### Claim 18 (depends on 11) The method of claim 11 where the fragments outside the tile region are rejected. ### Claim 19 (depends on 11) The method of claim 11 where data are further compressed using run length encoding. ### Claim 20 A device that reads metadata, compressed delta color values, and run-length encoded values from multiple tiles; decompresses them in an ordered fashion and displays them on an external display device.