1. A method of reducing a blocking artifact appearing when coding a picture, comprising:
dividing the picture into blocks that each include multiple pixels, the picture including a first pixel of a first block separated from a second pixel of a neighboring second block by a block boundary;
calculating an adjustment magnitude based on performing a clipping operation using the first pixel and the second pixel, wherein the adjustment magnitude is no greater than half of the difference between a value of the first pixel and a value of the second pixel; and
adjusting the first pixel based on the adjustment magnitude.
2. The method of claim 1,
wherein adjusting the first pixel further comprises replacing a pixel value v3 of the first pixel with an adjusted pixel value v3\u2032,
wherein the adjusted pixel value v3\u2032 is expressed as:
v3\u2032=v3\u2212d
wherein d is expressed as:
d
=
CLIP
\u2061
(
c
2
\u2061
(
a
3
,
0
\u2032
–
a
3
,
0
)
c
3
,
0
,
(
v
3
–
v
4
)
2
)
*
\u03b4
\u2061
(
\uf603
a
3
,
0
\uf604
<
QP
)
,
wherein a3,0\u2032 is expressed as:
a3,0\u2032=SIGN(a3,0)*MIN(|a3,0|, |a3,1|, a3,2|), and
wherein QP represents a quantization parameter of the second block, c2 and c3 represent DCT kernel coefficients, and v4 represents a pixel value of the second pixel.
3. The method of claim 2, wherein \u03b4(|a3,0|<QP)=1 if |a3,0|<QP, and wherein \u03b4(|a3,0|<QP)=0 if |a3,0|>QP.
4. The method of claim 2, wherein c2 is an integer and c3 is a multiple of 2.
5. The method of claim 4, wherein c2=5 and c3=8.
6. The method of claim 1, further comprising applying the adjusting operation to a spatial domain of the first pixel.
7. The method of claim 1, wherein the block boundary is a vertical or horizontal block boundary.
8. The method of claim 1, further comprising adjusting the second pixel based upon the adjustment magnitude.
9. The method of claim 1, wherein the clipping operation is performed using frequency information of the second pixel.
10. The method of claim 1, wherein the clipping operation is performed using a minimum magnitude of frequency information of the first and second pixels.
11. The method of claim 1, wherein the clipping operation is performed using frequency information of the first pixel and the second pixel.
12. The method of claim 1, further comprising obtaining frequency information for the second pixel, wherein the first pixel is adjusted if a magnitude of the blocking artifact is less than a quantization parameter of the second block.
13. The method of claim 1, wherein the adjustment magnitude is further based upon a simple inner product of a DCT kernel and the first and second pixels.
14. An apparatus for reducing a blocking artifact appearing when coding a picture, the apparatus comprising a blocking filter configured to:
divide the picture into blocks that each include multiple pixels, the picture including a first pixel of a first block separated from a second pixel of a neighboring second block by a block boundary;
calculate an adjustment magnitude based on performing a clipping operation using the first pixel and the second pixel, wherein the adjustment magnitude is no greater than half of the difference between a value of the first pixel and a value of the second pixel; and
adjust the first pixel based on the adjustment magnitude.
15. An apparatus for reducing a blocking artifact appearing when coding a picture, the apparatus comprising:
means for dividing the picture into blocks that each include multiple pixels, the picture including a first pixel of a first block separated from a second pixel of a neighboring second block by a block boundary;
means for calculating an adjustment magnitude based on performing a clipping operation using the first pixel and the second pixel, wherein the adjustment magnitude is no greater than half of the difference between a value of the first pixel and a value of the second pixel; and
means for adjusting the first pixel based on the adjustment magnitude.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A device, comprising:
an extractor to provide extracted short-time spectra by extracting short-time spectra or derived short-time spectra having at least one of harmonic or percussive portions from an information signal;
a decomposer to decompose the extracted short-time spectra into component signal spectra representing profile spectra for a plurality of tone sources, the profile spectra determined in part by a reduced number of the extracted short-time spectra resulting from a weighted linear combination of the extracted short-time spectra; and
a calculator to calculate a plurality of amplitude envelopes over time on the basis of the profile spectra and the extracted short-time spectra, the plurality of amplitude envelopes corresponding to the plurality of tone sources.
2. The device of claim 1, wherein the extractor further comprises:
at least one high-pass filter.
3. The device of claim 1, wherein the extractor further comprises:
a differentiator.
4. The device of claim 1, wherein the extractor further comprises:
a maximum searcher.
5. The device of claim 4, wherein the maximum searcher is to receive input comprising phase information derived from the information signal.
6. The device of claim 1, wherein the extractor is to implement a smoothed summation of the extracted short-time spectra to provide a detection function over time.
7. The device of claim 1, wherein the decomposer is to perform a principal component analysis.
8. The device of claim 1, wherein the decomposer is to perform an independent component analysis.
9. The device of claim 1, further comprising:
a classifier to classify the component signal spectra into percussive component signals and non-percussive component signals based on at least one of the amplitude envelopes or the profile spectra.
10. A method, comprising:
extracting short-time spectra or derived short-time spectra having at least one of harmonic or percussive portions from an information signal to provide extracted short-time spectra;
decomposing the extracted short-time spectra into component signal spectra representing profile spectra for a plurality of tone sources, the profile spectra determined in part by a reduced number of the extracted short-time spectra resulting from a weighted linear combination of the extracted short-time spectra; and
calculating a plurality of amplitude envelopes over time on the basis of the profile spectra and the extracted short-time spectra, the plurality of amplitude envelopes corresponding to the plurality of tone sources.
11. The method of claim 10, comprising:
transforming the information signal into at least one of an amplitude or a phase spectrogram.
12. The method of claim 11, wherein the transforming is accomplished using a Fourier transform and a selected hopping period.
13. The method of claim 11, wherein the extracting further comprises:
differentiation along a temporal expansion of the amplitude spectrogram.
14. The method of claim 10, wherein the decomposing further comprises:
performing a principal component analysis on the extracted short-time spectra.
15. The method of claim 10, wherein the decomposing further comprises:
decorrelating the extracted short-time spectra.
16. The method of claim 10, wherein the decomposing further comprises:
normalizing the extracted short-time spectra.
17. The method of claim 10, wherein the decomposing further comprises:
performing an independent component analysis on the extracted short-time spectra.
18. The method of claim 10, comprising:
classifying the profile spectra into percussive and non-percussive subsets.
19. The method of claim 10, comprising:
comparing a feature extracted from the profile spectra or the amplitude envelopes with features of known sources stored in a database to classify at least one of the known sources
20. A tangible computer storage medium having stored thereon a computer program which, when executed by a computer, results in the computer performing a method comprising:
extracting short-time spectra or derived short-time spectra having at least one of harmonic or percussive portions from an information signal to provide extracted short-time spectra;
decomposing the extracted short-time spectra into component signal spectra representing profile spectra for a plurality of tone sources, the profile spectra determined in part by a reduced number of the extracted short-time spectra resulting from a weighted linear combination of the extracted short-time spectra; and
calculating a plurality of amplitude envelopes over time on the basis of the profile spectra and the extracted short-time spectra, the plurality of amplitude envelopes corresponding to the plurality of tone sources.