Noise detecting method, noise detector and image decoding apparatus

• US 6,748,113 B1
• Filed: 08/25/2000
• Issued: 06/08/2004
• Est. Priority Date: 08/25/1999
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Takahashi, Hideya, Kondo, Satoshi, Taniuchi, Hiroshi, Iwasaki, Eiji
• Primary Examiner(s): Wu, Jingge
• Application Number:
  US09/645,579
• Time in Patent Office: 1,383 Days
• Field of Search: 382/232-253, 382/275, 375/240-242, 348/409-416
• US Class Current: 382/232
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• 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 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• 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 19/527 Global motion vector estimation
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A block boundary where blocking artifact occurs or a lock where ringing artifact occurs is definitely detected. The noise detecting method includes the steps of: extracting coding information, including orthogonal transformation coefficients and a motion vector of each of multiple blocks of an image, from a bitstream that has been encoded through motion compensation of the image, orthogonal transformation and quantization, where the orthogonal transformation is performed on each said block; obtaining a reference area of each said block from a reference frame using the motion vector of the block; and detecting coding noise to be eliminated according to frequency component distributions of the orthogonal transformation coefficients of each said block and another one of the blocks within the reference frame overlapping the reference area of the block.

Claims

1. A noise detecting method comprising the steps of:

extracting coding information, including orthogonal transformation coefficients and a motion vector of each of multiple blocks of an image, from a bitstream that has been encoded through motion compensation of the image, orthogonal transformation and quantization, where the orthogonal transformation is performed on each said block;

obtaining a reference area of each said block from a reference frame using the motion vector of the block; and

detecting coding noise to be eliminated according to frequency component distributions of the orthogonal transformation coefficients of each said block and another one of the blocks within the reference frame overlapping the reference area of the block,

said detecting coding noise comprises a sub-step of obtaining new classes of a target one of the blocks and another one of the blocks which is adjacent to the target block, according to classes of the target and adjacent blocks and classes of other ones of the blocks that overlap reference areas of the target and adjacent blocks within the reference frame.

2. The noise detecting method of claim 1, wherein blocking artifact is detected as the coding noise, and

wherein the coding noise detecting step includes the sub-steps of:

classifying each said block into any of a plurality of classes according to the frequency component distribution of the orthogonal transformation coefficients of the block; and

detecting magnitude of blocking artifact occurring between the target and adjacent blocks according to the new classes.

3. The noise detecting method of claim 1, wherein blocking artifact is detected as the coding noise, and

wherein the coding noise detecting step includes the sub-steps of:

extracting DC components of the orthogonal transformation coefficients of a target one of the blocks and another one of the blocks that is adjacent to the target block from the coding information; and

detecting magnitude of blocking artifact occurring between the target and adjacent blocks according to not only the frequency component distribution of the orthogonal transformation coefficients but also an absolute value of a difference in the DC component between the target and adjacent blocks.

4. The noise detecting method of claim 3, wherein the coding noise detecting step includes the sub-steps of:

extracting a quantizer scale of the target block from the coding information; and

detecting magnitude of blocking artifact occurring between the target and adjacent blocks according to not only the frequency component distribution of the orthogonal transformation coefficients but also the absolute value of the difference in the DC component and the quantizer scale.

5. The noise detecting method of claim 1, wherein the coding noise to be eliminated is detected according to not only the frequency component distribution of the orthogonal transformation coefficients but also a size of the motion vector of a target one of the blocks or another one of the blocks that is adjacent to the target block.

6. The noise detecting method of claim 5, wherein blocking artifact is detected as the coding noise, and

wherein the coding noise detecting step includes the sub-steps of:

extracting DC components of the orthogonal transformation coefficients of the target and adjacent blocks from the coding information; and

detecting magnitude of blocking artifact occurring between the target and adjacent blocks according to not only the frequency component distribution of the orthogonal transformation coefficients and the size of the motion vector but also an absolute value of a difference in the DC component between the target and adjacent blocks.

7. The noise detecting method of claim 6, wherein the coding noise detecting step includes the sub-steps of:

extracting a quantizer scale of the target block from the coding information; and

detecting magnitude of blocking artifact occurring between the target and adjacent blocks according to not only the frequency component distribution of the orthogonal transformation coefficients and the size of the motion vector but also the absolute value of the difference in the DC component and the quantizer scale.

8. The noise detecting method of claim 1, wherein the coding noise detecting step is carried out on each of multiple fields in an interlaced image.

9. A noise detector comprising:

means for receiving coding information as an input, detecting coding noise to be eliminated and outputting a result of the detection,

wherein the coding information includes orthogonal transformation coefficients and a motion vector of each of the multiple blocks of an image,

the coefficients and vector are obtained from a bitstream that has been encoded through motion compensation of the image, orthogonal transformation and quantization, where the orthogonal transformation is performed on each said block,

the coding noise is detected according to frequency component distributions of the orthogonal transformation coefficients of each said block and another one of the blocks within a reference frame overlapping a reference area of the block, and

the reference area is obtained from the reference frame using the motion vector of each said block,

said detecting coding noise means obtains new classes of a target one of the blocks and another one of the blocks, which is adjacent to the target block, according to classes of the target and adjacent blocks and classes of other ones of the blocks that overlap reference areas of the target and adjacent blocks within the reference frame.