Interlace motion artifact detection using vertical frequency detection and analysis
View Patent ↗An interlace motion artifact detector which identifies video image spatial frequencies characteristic of motion artifacts. The detected frequency is the maximum which can be represented by the vertical sampling rate of the video format (i.e., the Nyquist frequency). This frequency is detected by a pair of partial Discrete Fourier Transforms (DFT) which each calculate only the frequency component of interest. Additional vertical frequency components at one half and one quarter the interlace motion artifact frequency are also detected via a partial DFT. The presence of these lower frequencies acts as an indication of an erroneous motion artifact detection. Additionally, the dynamic range and maximum level of the video data is used as an indication of when to boost the frequency detection levels in areas of low brightness and/or contrast.
1. A system for the reduction of interlace motion artifacts by vertical frequency analysis comprising:
a) a four-point partial discrete fourier transform module responsive to a set of four vertically aligned luma or chroma data sample inputs selected from and approximately centered about a set of eight vertically aligned luma or chroma data sample inputs and operative to develop a first frequency detection value;
b) an eight-point partial discrete fourier transform module responsive to the set of eight vertically aligned luma or chroma data sample inputs and operative to develop a second, third and fourth frequency detection value;
c) a dynamic range/maximum detection module responsive to the set of eight vertically aligned luma or chroma data sample inputs in conjunction with pixel data from a two-dimensional array surrounding a current input pixel and operative to develop a maximum data value and a range value;
d) a horizontal lowpass filter module responsive to the first, second, third and fourth frequency detection values and operative to develop filtered first, second, third and fourth frequency detection values;
e) a detection value boost module responsive to the filtered first, second, third and fourth frequency detection values, the maximum data value and the range value, operative to develop a level boosted four-point f max frequency detection value, a level boosted eight-point f max frequency detection value, a level boosted f max /2 frequency detection value and a level boosted f max /4 frequency detection value;
f) an averaging module responsive to the level boosted four-point frequency detection value and the level boosted eight-point frequency detection value, operative to develop a numeric average;
g) a threshold comparison/level correction module responsive to the numeric average, the level boosted f max /2 frequency detection value and the level boosted f max /4 frequency detection value, operative to develop a level-corrected f max frequency detection value;
h) a horizontal weighted average module responsive to the level-corrected f max frequency detection value and operative to develop a center-weighted, horizontal frequency detection value; and
i) a threshold adjust module responsive to the center-weighted horizontal frequency detection value and operative to develop a final frequency detection value.
2. A system as in claim 1 , wherein the luma or chroma data is luma data.
3. A system as in claim 1 , wherein the luma or chroma data is chroma data.
4. A system as in claim 1 , wherein the luma or chroma data comprises luma data and chroma data.
5. A method for the reduction of interlace motion artifacts by vertical frequency analysis, the method comprising:
a) performing a four-point partial discrete Fourier transform responsive to a set of four vertically aligned luma or chroma data sample inputs selected from and approximately centered about a set of eight vertically aligned luma data sample inputs and generating a first frequency detection value;
b) performing an eight-point partial discrete Fourier transform responsive to the set of eight vertically aligned luma or chroma data sample inputs and generating a second, third, and fourth frequency detection value;
c) performing a dynamic range/maximum detection operation responsive to the set of eight vertically aligned luma or chroma data sample inputs in conjunction with pixel data from a two-dimensional array surrounding a current input pixel and generating a maximum data value and a range value;
d) performing a horizontal low-pass filter operation responsive to the first, second, third, and fourth frequency detection values and generating filtered first, second, third, and fourth frequency detection values;
e) performing a detection value boost operation responsive to the filtered first, second, third, and fourth frequency detection values, the maximum data value and the range value, and generating a level boosted four-point f max frequency detection value, a level boosted eight-point f max frequency detection value, a level boosted f max /2 frequency detection value, and a level boosted f max /4 frequency detection value;
f) performing an averaging operation responsive to the level boosted four-point frequency detection value and the level boosted eight-point frequency detection value, and generating a numeric average;
g) performing a threshold comparison/level correction operation responsive to the numeric average, the level boosted f max /2 frequency detection value, and the level boosted f max /4 frequency detection value, and generating a level-corrected f max frequency detection value;
h) performing a horizontal weighted average operation responsive to the level-corrected f max frequency detection value and generating a center-weighted, horizontal frequency detection value; and
i) performing a threshold adjust operation responsive to the center-weighted horizontal frequency detection value and generating a final frequency detection value.
6. A method as in claim 5 , wherein the luma or chroma data is luma data.
7. A method as in claim 5 , wherein the luma or chroma data is chroma data.
8. A method as in claim 5 , wherein the luma or chroma data comprises luma data and chroma data.
9. A system for the reduction of interlace motion artifacts comprising:
a) a partial discrete Fourier transform module responsive to a set of vertically aligned luma or chroma data sample inputs selected from and approximately centered about a set of vertically aligned luma or chroma data sample inputs and operative to develop a first frequency detection value;
b) a partial discrete Fourier transform module responsive to the set of vertically aligned luma or chroma data sample inputs and operative to develop a plurality of additional frequency detection values;
c) a dynamic range/maximum detection module responsive to the set of vertically aligned luma or chroma data sample inputs in conjunction with pixel data from a two-dimensional array surrounding a current input pixel and operative to develop a maximum data value and a range value;
d) a horizontal lowpass filter module responsive to the frequency detection values and operative to develop filtered frequency detection values;
e) a detection value boost module responsive to the filtered frequency detection values, the maximum data value and the range value, operative to develop a plurality of level boosted frequency detection values;
f) an averaging module responsive to the level boosted frequency detection values, operative to develop a numeric average;
g) a threshold comparison/level correction module responsive to the numeric average, at to at least one of the level boosted frequency detection values operative to develop a level-corrected frequency detection value;
h) a horizontal weighted average module responsive to the level-corrected frequency detection value and operative to develop a center-weighted, horizontal frequency detection value; and
i) a threshold adjust module responsive to the center-weighted horizontal frequency detection value and operative to develop a final frequency detection value.
10. A method for the reduction of interlace motion artifacts comprising:
a) performing a partial discrete Fourier transform responsive to a set of vertically aligned luma or chroma data sample inputs selected from and approximately centered about a set of vertically aligned luma or chroma data sample inputs and generating a first frequency detection value;
b) performing a partial discrete Fourier transform operation responsive to the set of vertically aligned luma or chroma data sample inputs and generating a plurality of additional frequency detection values;
c) performing a dynamic range/maximum detection operation responsive to the set of vertically aligned luma or chroma data sample inputs in conjunction with pixel data from a two-dimensional array surrounding a current input pixel and generating a maximum data value and a range value;
d) performing a horizontal low-pass filter operation responsive to the frequency detection values and generating filtered frequency detection values;
e) performing a detection value boost operation responsive to the filtered frequency detection values, the maximum data value and the range value, generating a plurality of level boosted frequency detection values;
f) performing an averaging operation responsive to the level boosted frequency detection values, operative to develop a numeric average;
g) performing a threshold comparison/level correction operation responsive to the numeric average, at to at least one of the level boosted frequency detection values generating a level-corrected frequency detection value;
h) performing a horizontal weighted average operation responsive to the level-corrected frequency detection value and generating a center-weighted, horizontal frequency detection value; and
i) performing a threshold adjust operation responsive to the center-weighted horizontal frequency detection value and generating a final frequency detection value.
11. A method as in claim 10 , wherein the luma or chroma data is luma data.
12. A method as in claim 10 , wherein the luma or chroma data is chroma data.
13. A method as in claim 10 , wherein the luma or chroma data comprises luma data and chroma data.
14. A Fourier transform unit comprising:
a four-point partial discrete Fourier transform module; and
an eight-point partial discrete Fourier transform module;
the four-point partial discrete Fourier transform module being responsive to a set of vertically aligned luma or chroma data sample inputs selected from and approximately centered about a set of vertically aligned luma or chroma data sample inputs and operative to develop a first frequency detection value; and
the eight-point partial discrete Fourier transform module being responsive to the set of eight vertically aligned luma or chroma data sample inputs and operative to develop at least one frequency detection value.
15. The Fourier transform unit in claim 14 , wherein:
the four-point partial discrete Fourier transform module being responsive to a set of four vertically aligned luma or chroma data sample inputs selected from and approximately centered about a set of eight vertically aligned luma or chroma data sample inputs and operative to develop a first frequency detection value; and
the eight-point partial discrete Fourier transform module being responsive to the set of eight vertically aligned luma or chroma data sample inputs and operative to develop a second, third and fourth frequency detection value.
16. The Fourier transform unit in claim 15 , further comprising:
a dynamic range/maximum detection module responsive to the set of eight vertically aligned luma or chroma data sample inputs in conjunction with pixel data from a two-dimensional array surrounding a current input pixel and operative to develop a maximum data value and a range value;
a horizontal lowpass filter module responsive to the first, second, third and fourth frequency detection values and operative to develop filtered first, second, third and fourth frequency detection values; and
a detection value boost module responsive to the filtered first, second, third and fourth frequency detection values, the maximum data value and the range value, operative to develop a level boosted four-point f max frequency detection value, a level boosted eight-point f max frequency detection value, a level boosted f max /2 frequency detection value and a level boosted f max /4 frequency detection value.