Method and apparatus for eliminating flicker by quantizing values based on previous quantization

• US 6,904,178 B2
• Filed: 03/06/2001
• Issued: 06/07/2005
• Est. Priority Date: 02/15/2001
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Gormish, Michael J., Schwartz, Edward L., Boliek, Martin
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): SHERALI, ISHRAT I
• Application Number:
  US09/801,218
• Publication Number:
  US 20040028284A1
• Time in Patent Office: 1,554 Days
• Field of Search: 382/251, 382/250, 382/248, 382232-233, 382/236, 382238-240, 382/274, 382/268, 382/275, 375/240.03, 375/240.1, 375/240.12, 375/240.16, 37524018-24027, 348/241, 348606-622
• US Class Current: 382/251
• CPC Class Codes: G11B 27/036 Insert-editing
• CPC Class Codes: H04N 19/10 using adaptive coding
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/129 Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/34 Scalability techniques involving progressive bit-plane based encoding of the enhancement layer, e.g. fine granular scalability [FGS]
• CPC Class Codes: H04N 19/36 Scalability techniques involving formatting the layers as a function of picture distortion after decoding, e.g. signal-to-noise [SNR] scalability
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• 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 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/426 : using memory downsizing methods
• CPC Class Codes: H04N 19/45 : performing compensation of the inverse transform mismatch, e.g. Inverse Discrete Cosine Transform [IDCT] mismatch
• CPC Class Codes: H04N 19/46 : Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/593 : involving spatial prediction techniques
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 19/619 : the transform being operated outside the prediction loop
• CPC Class Codes: H04N 19/63 : using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/635 : characterised by filter definition or implementation details
• CPC Class Codes: H04N 19/64 : characterised by ordering of coefficients or of bits for transmission
• CPC Class Codes: H04N 19/645 : by grouping of coefficients into blocks after the transform
• CPC Class Codes: H04N 19/647 : using significance based coding, e.g. Embedded Zerotrees of Wavelets [EZW] or Set Partitioning in Hierarchical Trees [SPIHT]
• CPC Class Codes: H04N 19/70 : characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/85 : using pre-processing or post-processing specially adapted for video compression
• CPC Class Codes: H04N 19/86 : involving reduction of coding artifacts, e.g. of blockiness

Abstract

A method and apparatus for eliminating flicker by quantizing values based on previous quantization is described. In one embodiment, the method comprises encoding a first coefficient value in a first frame of a motion sequence and subsequently setting a second coefficient in a second frame of the motion sequence and in the same position as the first coefficient to be within a predetermined closeness with the value of the first coefficient.

Claims

1. A method for reducing flicker comprising:

encoding a first coefficient value in a first region of a first frame of a motion sequence;

subsequently setting a second coefficient in a second region of a second frame of the motion sequence and in substantially the same position as the first region of the first frame to be within a predetermined closeness with the value of the first coefficient; and

setting at least a portion of remaining regions other than the second region of the second frames with values different than a corresponding portion of the first frame.

2. The method defined in claim 1 wherein the predetermined closeness is within a quantization bin size.

3. The method defined in claim 1 wherein the predetermined closeness is within twice a quantization bin size.

4. The method defined in claim 1 wherein the second coefficient is set to the same value as the first coefficient.

5. The method defined in claim 1 further comprising determining whether quantization is applied to the first coefficient, wherein setting the second coefficient occurs only if the same quantization was applied to the first coefficient.

6. The method defined in claim 1 wherein setting the second coefficient to the value near the first coefficient occurs only if the absolute value of a difference between a quantized version of the first coefficient and a result of applying a scalar quantization to the second coefficient is less than a threshold value.

7. The method defined in claim 6 wherein the threshold comprises a value equal to twice the quantization step size.

23. The method of claim 1, wherein the first and second frames are consecutive frames.

24. The method of claim 1, wherein there is at least one other frame between the first and second frames of the motion sequence.

25. The method of claim 6, wherein the scalar quantization has a value of Q, and wherein the threshold value is selected as one of {square root over (2)}Q, 1.5Q, and 2{square root over (2)}Q.

26. The method of claim 6, wherein the threshold value is determined based on subband information of the motion sequence.

27. The method of claim 6, wherein the threshold value is determined based on a number of frames that include a corresponding region having a coefficient close to the first coefficient of the first frame.

8. An article of manufacture comprising at least one recordable media storing executable instructions thereon which, when executed by a processing device for reducing flicker, cause the processing device to:

encode a first coefficient value in a first region of a first frame of a motion sequence;

subsequently setting a second coefficient in a second region of a second frame of the motion sequence and in substantially the same position as the first region of the first frame to be within a predetermined closeness with the value of the first coefficient; and

setting at least a portion of remaining regions other than the second region of the second frames with values different than a corresponding portion of the first frame.

9. The article of manufacture defined in claim 8 wherein the predetermined closeness is within a quantization bin size.

10. The article of manufacture defined in claim 8 wherein the predetermined closeness is within twice a quantization bin size.

11. The article of manufacture defined in claim 8 wherein the second coefficient is set to the same value as the first coefficient.

12. An apparatus for reducing flicker comprising:

means for encoding a first coefficient value in a first region of a first frame of a motion sequence;

means for subsequently setting a second coefficient in a second region of a second frame of the motion sequence and in substantially the same position as the first region of the first frame to be within a predetermined closeness with the value of the first coefficient; and

means for setting at least a portion of remaining regions other than the second region of the second frames with values different than a corresponding portion of the first frame.

13. The apparatus defined in claim 12 wherein the predetermined closeness is within a quantization bin size.

14. The apparatus defined in claim 12 wherein the predetermined closeness is within twice a quantization bin size.

15. The apparatus defined in claim 12 wherein the second coefficient is set to the same value as the first coefficient.

16. An encoding apparatus for reducing flicker comprising:

a wavelet transform;

a quantizer coupled to the wavelet transform, the quantizer comprising;

a first memory to store a threshold value,

a second memory to store quantized versions of coefficients in a plurality of regions of a previous frame of a motion sequence, including a first region, and

quantization logic to set a first coefficient value in second region of a subsequent frame to a value within a predetermined closeness to that of a second coefficient at substantially the same position in the first region of the previous frame, and to set at least a portion of a remaining regions of the subsequent frame to values different than corresponding portion of the previous frame.

17. The encoding apparatus defined in claim 16 wherein the quantization logic determines whether quantization is applied to the first coefficient and sets the second coefficient occurs only if quantization was applied to the first coefficient.

18. The encoding apparatus defined in claim 16 wherein the quantization logic sets the second coefficient to the value of the first coefficient only if the absolute value of a difference between a quantized version of the first coefficient and a result of applying a scalar quantization to the second coefficient is less than a threshold value.

19. The encoding apparatus defined in claim 16 wherein the threshold comprises a value equal to twice the quantization step size.

20. The encoding apparatus defined in claim 16 wherein the predetermined closeness is within a quantization bin size.

21. The encoding apparatus defined in claim 16 wherein the predetermined closeness is within twice a quantization bin size.

22. The encoding apparatus defined in claim 16 wherein the second coefficient is set to the same value as the first coefficient.