Method and apparatus for implementing a processor based on the rationalized Haar transform for the purpose of real time compression of video data

• US 4,224,678 A
• Filed: 04/05/1976
• Issued: 09/23/1980
• Est. Priority Date: 04/05/1976
• Status: Expired due to Term

• Current Assignee: Northrop Corporation
• Original Assignee: Northrop Corporation
• Inventors: Reis, James J., Lynch, Robert T.
• Primary Examiner(s): Malzahn, David H.
• Application Number:
  US05/673,799
• Time in Patent Office: 1,632 Days
• Field of Search: 235/152, 235/156, 178/DIG. 3, 179/15 AV, 179/15 BW, 179/15.55 R, 364/724, 358/133
• US Class Current: 708/203
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/132 Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

A method and apparatus is described for implementing a real time video processing system based on the rationalized Haar transform. The system operates in real time to remove redundant information from video data for the purpose of compressing the video bandwidth. A digital apparatus for implementing the system is described which is capable of processing video in real time at data rates up to 60 M bits per second.

Claims

1. A filter system for encoding transform coefficients representing video data to substantially reduce the number of bits therein comprising:

zonal filter means for receiving said transform coefficients and separating preselected coefficients for compression from coefficients not to be compressed,

threshold filter means coupled to the output of said zonal filter means for receiving the preselected coefficients for compression and deleting transform coefficients below a predetermined magnitude therefrom,

multiplier means coupled to the output of said threshold filter for eliminating a preselected number of least significant digits from said transform coefficients,

edge enhancer filter means coupled to the output of said multiplier means for multiplying various preselected higher order transform coefficients to provide edge enhancement thereof,

compander means coupled to the output of said edge enhancement filter means for providing further compression of said transform coefficients by various non-linear companding based on an integer log functional rule, and

adaptive filter means coupled to the output of said compander for selecting the N largest magnitude coefficients to thereby provide filter digitized transformed video data.

2. The system as described in claim 1 and further including statistical processor means coupled to the output of said adaptive filter means for providing probability density information of the filtered digitized transformed data.

3. The system as described in claim 1 and wherein said threshold filter means includes a plurality of digital comparators.

4. The system as described in claim 1 and wherein said multiplier means includes means for multiplying the output of said threshold filter by 2^-N.

5. The system as described in claim 4 and wherein said means for multiplying the output of said threshold filter by 2^-N includes a hard wired binary shift register.

6. The system as described in claim 1 and wherein said edge enhancement filter means includes a position scaler.

7. The system as described in claim 1 and wherein said compander means includes an integer log₂ compander.

8. The system as described in claim 7 and wherein said integer log₂ compander includes a read-only-memory.

9. The system as described in claim 7 and wherein said integer log₂ compander includes a priority encoder.

10. The system as described in claim 1 and wherein said adaptive filter means includes a plurality of comparators and data registers.

11. A real time video bandwidth compression system comprising:

means for providing a digital data signal representing video data,

Haar transformer means for converting said digital data signal to a transform domain signal represented by Haar transform coefficients,

filter means coupled to the output of said transformer for selectively encoding the transform coefficients to provide a transform domain signal having a substantially decreased number of bits, thereby compressing the transform domain signal, said filter means including threshhold filter means for deleting coefficients below a predetermined numerical value, and

transmitting modem means coupled to the output of said filter means for modulating a carrier signal with the compressed transform domain signal and transmitting said modulated carrier signal.