Reduction of errors during computation of inverse discrete cosine transform

A technique for transforming coefficients and vectors, used in computer graphics and multimedia
CN102016829AActive Publication Date: 2011-04-13QUALCOMM INC
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
QUALCOMM INC
Publication Date
2011-04-13

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Abstract

Techniques are described to reduce rounding errors during computation of discrete cosine transform using fixed-point calculations. According to these techniques, an inverse discrete cosine transform a vector of coefficients is calculated using a series of butterfly structure operations on fixed-point numbers. Next, a midpoint bias value and a supplemental bias value are added to a DC coefficient of the matrix of scaled coefficients. Next, an inverse discrete cosine transform is applied to the resulting matrix of scaled coefficients. Values in the resulting matrix are then right-shifted in order to derive a matrix of pixel component values. As described herein, the addition of the supplemental bias value to the DC coefficient reduces rounding errors attributable to this right-shifting. As a result, a final version of a digital media file decompressed using these techniques may more closely resemble an original version of a digital media file.
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Description

[0001] This application claims US Provisional Application No. 60 / 816,697, filed on June 26, 2006, US Provisional Application No. 60 / 841,362, filed on August 30, 2006, and No. 60, filed on September 25, 2006 U.S. Provisional Application No. 847,194, U.S. Provisional Application No. 60 / 829,669, filed Oct. 16, 2006, and U.S. Provisional Application No. 60 / 869,530, filed Dec. 11, 2006, the aforementioned provisional applications is incorporated herein by reference in its entirety. technical field

[0002] The present invention relates to computer graphics and multimedia, and more particularly, to the compression of graphics, images and video information. Background technique

[0003] Many existing image and video coding standards use compression techniques to allow high resolution images and video to be stored or transmitted as relatively compact files or data streams. Such coding standards include Joint Photographic Experts Group (JPEG), Moving Pictures Experts Group (MPEG)-1,...

Claims

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