Tiling or blockiness detection based on spectral power signature
AssigneeTektronix, Inc.
InventorDaniel G. Baker
Life of this patent
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Abstract
Tiling or blockiness detection based on spectral power signature uses one-dimensional vectors at block edges to find a spectral signature created by the tiling or blockiness in an image. A baseband component of the image, such as luminance, is edge enhanced, and then the pixel values along each horizontal line are summed to form a one-dimensional column vector of summed edge values for the image. The power of the column vector and the power of selected frequency components within the column vector are determined. The powers are then combined and converted to dimensionless tiling or blockiness values relative to each of the selected frequencies.
Claims18
A computer-implemented method of detecting tiling or blockiness in an image comprising executing on a processor the steps of:
- generating from a column vector generator a column vector of edge values for the image;
- inputting the column vector into a power determiner;
- determining from the power determiner a power value for the column vector and a power value for each of a group of predetermined frequencies by:
- calculating the power value from an AC component of the column vector by:
- determining a mean value for the column vector from the edge values,
- subtracting the mean value from each edge value in the column vector to produce the AC component of the column vector, and
- producing the power value for the column vector as the sum of the squares of the values for the AC component of the column vector,
- calculating power values for 1 and Q components of the AC component of the column vector at each of the predetermined frequencies, and
- summing the power values for the I and Q components of each predetermined frequency to produce the power value for each predetermined frequency;
- and
- combining via a combiner the power values to produce a tiling or blockiness value for each of the predetermined frequencies.
An apparatus for detecting tiling or blockiness in an image comprising:
- means for generating a column vector of edge values for the image;
- means for determining from the column vector a power value for the column vector and a power value for each of a group of predetermined frequencies, the determining means including:
- means for calculating the power value from an AC component of the column vector, the column vector power value calculating means comprises:
- means for determining a mean value for the column vector from the edge values;
- means for subtracting the mean value from each edge value in the column vector to produce the AC component of the column vector, and
- means for producing the power value for the column vector as the sum of the squares of the values for the AC component of the column vector,
- means for calculating power values for I and Q components of the column vector at each of the predetermined frequencies, and
- means for summing the power values for the I and Q components of each predetermined frequency to produce the power value for each predetermined frequency;
- and
- means for combining the power values to produce a tiling or blockiness value for each of the predetermined frequencies.
An apparatus for detecting tiling or blockiness in an image comprising:
- a column vector generator having as an input data representing the image and providing as an output a column vector of edge values for the image;
- a power determiner having as an input the column vector and providing as outputs a power value for the column vector and for predetermined frequencies within the column vector, the power determiner includes:
- a first power calculator having as an input an AC component of the column vector and having as an output the power value for the column vector, the first power calculator includes:
- a DC determiner having the edge values of the column vector as an input and producing a mean value of the edge values as an output,
- a subtractor having as a first input the edge values of the column vector and as a second input the mean value to produce the AC component of the column vector as the difference of the edge values and the mean value as an output, and
- a power generator having the AC component as an input and producing the power value for the column vector as the sum of the squares of the edge values for the AC component of the column vector as an output,
- a second power calculator having as an input the AC component of the column vector and having as outputs power values for I and Q components of the column vector at each of the predetermined frequencies, and
- a summer having as inputs the power values for the I and Q components of each predetermined frequency and having as outputs the power values for each predetermined frequency;
- and
- a combiner having as inputs the power values for the column vector and the predetermined frequencies, and providing as outputs a tiling or blockiness value for each of the predetermined frequencies.
Dependencies are inferred from the claim text.