Method and apparatus for measuring the noise contained in a picture
AssigneeMicronas GmbH
InventorsMarko Hahn, Dirk Wendel, Ulrich Niedermeier
Life of this patent
Estimating the term…
Abstract
To determine the noise contained in a picture, it is proposed first to determine homogeneous picture regions of the picture (100-102) and then to measure the high-frequency signal component in these homogeneous picture regions (BR). The measurement of the high-frequency signal components is here averaged over many measurement points, i.e. over many homogenous picture regions (BR), and is processed into a noise figure (NOISE_SUM) (103-104). In this way, the quality of the picture can be measured directly in the picture content.
Claims17
A method for measuring the noise in a picture that includes a plurality of lines, comprising:
- receiving a digital picture signal that includes a plurality of pixels indicative of the picture;
- subdividing a line of said digital picture signal into several blocks (BL), each with several horizontally adjoining pixels, wherein a picture region (BR) includes a plurality of said blocks (BL) and the number of said blocks contained within said picture region (BR) corresponds to the number of pixels contained in each block (BL);
- determining a luminance DC component value for each of picture blocks;
- processing for said picture region, said luminance DC component values associated with each of a plurality of blocks within said picture region, by comparing each of said luminance DC components to a minimum threshold value and a maximum threshold value, to detect at least one homogeneous picture region (BR) within the picture;
- determining a high frequency component (HP) within said at least one detected homogeneous picture region (BR);
- processing said high-frequency signal component (HP) to determine the noise contained in the picture and providing a noise signal indicative thereof;
- wherein
- said luminance DC component of each block (BL) is determined by the following relation
- LP
-
- (
- x
- ′
- ,
- y
- )
- =
- ∑
- i
- =
- 0
- n
-
- lum
-
- (
- i
- +
- nx
- ′
- ,
- y
- )
- ,
- where LP designates the luminance of DC component of the corresponding block (BL), (x′,y) designates the position of the corresponding block (BL) in the picture, lum designates the luminance value or the difference luminance value of the corresponding pixel, and n designates the number of horizontally adjoining pixels contained in the corresponding block (BL);
- wherein each block (BL) contains five horizontally adjoining pixels, and for each block (BL) of the picture region (BR) which is recognized as homogeneous, a high frequency signal component (HP) is determined by the following relation
- HP(x′,y)=lum(5x′,y)−2lum(1+5x′,y)+2lum(2+5x′,y)−2lum(3+5x′,y)+lum(4+5x′,y),
- where HP designates the coefficient of the corresponding block (BL), (x′,y) designates the position of the corresponding block (BL) in the picture, and lum designates the luminance value or the difference luminance value of the respective pixel.
A method for measuring the noise contained in a picture, by which the picture is described by an appropriate picture signal, comprising:
- receiving a picture signal and processing said picture signal to detect at least one homogeneous picture region (BR) of the picture;
- for the at least one detected homogeneous picture region (BR), measuring a high-frequency signal component (HP) contained in said picture signal;
- and
- determining the noise contained in the picture from the high-frequency signal component (HP) and providing a noise signal indicative thereof.
A method for measuring the noise contained in a video picture, comprising:
- receiving a video picture signal and processing said video picture signal to detect at least one homogeneous picture region of the picture;
- for the at least one detected homogeneous picture region, measuring a high-frequency signal component contained in said video picture signal;
- and
- determining the noise contained in the picture from the high-frequency signal component and providing a noise signal indicative thereof.
A method for measuring noise contained in a video picture that includes a plurality of regions, comprising:
- processing said video picture region-by-region, wherein each region includes a plurality of blocks and each of the blocks includes a plurality of adjacent pixels;
- processing each region to determine if the region is a homogeneous region;
- for at least one detected homogeneous region of the picture, on a block-by-block basis determining a high-frequency signal for each block associated with the homogeneous region of the picture and providing a high-frequency signal indicative thereof;
- and
- determining the noise contained in the picture from the high-frequency signals and providing a noise signal indicative thereof.
An apparatus that measures noise contained in a video picture that includes a plurality of regions, wherein each region includes a plurality of blocks and each of the blocks includes a plurality of adjacent pixels, said apparatus comprising:
- means for processing each region to determine if the region is a homogeneous region;
- means for determining a high-frequency signal for each block associated with the detected homogeneous region of the picture and for providing a high-frequency signal indicative thereof;
- and
- means for determining the noise contained in the picture from the high-frequency signals and for providing a noise signal indicative thereof.
Dependencies are inferred from the claim text.