Method and apparatus for using minimal and optimal amount of SRAM delay line storage in the calculation of an X Y separable mallat wavelet transform

• US 5,984,514 A
• Filed: 12/20/1996
• Issued: 11/16/1999
• Est. Priority Date: 12/20/1996
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Rossman, Mark, Greene, Richard, Hallmark, Phil
• Primary Examiner(s): Ramirez, Ellis B.
• Application Number:
  US08/770,518
• Time in Patent Office: 1,061 Days
• Field of Search: 395/200.77, 364/715.02, 348/398, 348/384, 348/422, 382/233
• US Class Current: 708/203
• CPC Class Codes: G06F 17/148 Wavelet transforms
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets

Abstract

A video compression circuit comprises an input that receives an input video signal. A memory buffer, coupled to the input, temporarily stores a portion of the input video signal. A single horizontal filter bank, coupled to the memory buffer, high-pass and low-pass filters horizontal components of the input video signal. A single vertical filter bank, also coupled to the memory buffer, high-pass and low-pass filters vertical components of the input video signal. A recursion buffer, coupled to the filter banks, temporarily stores filter components of the input video signal for recursive filtering.

Claims

1. A video compression system comprising:

an input that receives an input video signal having at least one frame;

a one-dimensional wavelet-based horizontal filter bank, coupled to the input, that, during each of a number of stages of recursion, receives input video data and filters horizontal components of the input video data to produce filtered horizontal components of the input video data, the input video data being equal to the input video signal during a first recursion stage;

a memory buffer, coupled to the horizontal filter bank, that temporarily stores a limited data portion of the filtered horizontal components during each recursion stage; and

a one-dimensional wavelet-based vertical filter bank, coupled to the memory buffer, that, for each stage of recursion, receives the limited data portion of the filtered horizontal components and filters vertical components of the limited data portion of the filtered horizontal components, to produce filtered vertical components of the limited data portion;

wherein, for each recursion stage except a final recursion stage, a portion of the filtered vertical components of the limited data portion is fed back as the input video data to be filtered by the horizontal filter bank during a next stage of recursion so as to produce, through all stages of recursion, a desired frequency plot having columns defining blocks of input video signal information among different frequency sub-bands;

wherein the limited data portion of filtered horizontal components stored in the memory buffer during each recursion stage is equal to N×

M×

W, where N is equal to the sum of the number of columns in the desired frequency plot for a level corresponding to the recursion stage, M is equal to a length of the filter bank-1, and W is a word length in bits of the input video signal.

2. The video compression system as claimed in claim 1 wherein each of the filter banks performs both high-pass and low-pass filtering.

3. The video compression system as claimed in claim 1 wherein each of the filter banks performs both analysis and synthesis.