Resampling methods

• US 20040145501A1
• Filed: 10/22/2003
• Published: 07/29/2004
• Est. Priority Date: 10/22/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Hung, Ching-Yu
• Granted Patent: US 7,333,141 B2
• Time in Patent Office: Days
• US Class Current: 341/61
• CPC Class Codes: G06T 3/4023 based on decimating pixels or lines of pixels; based on inserting pixels or lines of pixels

Abstract

Polyphase filtering, such as resampling for image resizing, on a processor with parallel output units is cast in terms of data access blocks and data coverage charts to increase processor efficiency. Automatic generation of implementations corresponding to input resampling factors by computation cost comparisons.

Claims

1. A method of resampling a data sequence, comprising:

(a) providing filter coefficients according to an input resampling ratio U/D where U and D are positive integers, said coefficients grouped into U sub-filters according to phase and corresponding to a data access block;

(b) for each of a plurality of architecture kernels;

(i) provide a step per group of H of said sub-filters from a first set of integers about H*D/U where H is the height of said architecture kernel;

(ii) for each of said steps from said first set, find a length for said sub-filters according to an access coverage chart for said data access block;

(c) using the architecture kernel and the step corresponding to a minimum of said lengths of step (b)(ii) to filter an input data sequence.

2. The method of claim 1, wherein:

(a) said filter coefficients of step (a) of claim 1 are samples of a windowed sinc function.

3. The method of claim 1, wherein:

(a) said input data sequence is an image; and

(b) said filter of step (c) of claim 1 is a horizontal resampling.

4. A digital camera zoom, comprising:

(a) an input for zoom selection; and

(b) parallel processing circuitry coupled to said zoom selection input and operable to resample an image by

(1) providing filter coefficients according to a resampling ratio dependent upon an input zoom selection, said coefficients grouped into sub-filters according to filter phase and corresponding to a data access block;

(2) for each of a plurality of architecture kernels of said parallel processing circuitry (i) provide a step per group of said sub-filters from a first set of integers corresponding to the height of said architecture kernel and said resampling ratio, (ii) for each of said steps from said first set, find a length for said sub-filters according to an access coverage chart for said data access block; and

(3) using the architecture kernel and the step corresponding to a minimum of said lengths of step (b)(ii) to filter said image.