Method and system for noise level detection in image data
AssigneeXerox Corporation
InventorStuart A. Schweid
Life of this patent
Estimating the term…
Abstract
A system determines the noise level of image data by high pass filtering image data. Absolutes values of the high pass filtered image data are determined. Thereafter, multiple mean values for absolute values less than a predetermined number of threshold values are determined. Based upon the determined mean values, a plurality of estimated mean values is calculated, each estimated mean value being calculated from a combination of two determined mean values. The noise of the image is determined from a combination of the minimum estimated mean value and the maximum estimated mean value. This noise can be optionally used by a sigma filter, at Step S740, to sigma filter the image data.
Claims20
A method for filtering image data, comprising:
- (a) obtaining a digital image;
- (b) high pass filtering the image data;
- (c) determining absolutes values of the high pass filtered image data;
- (d) determining a mean value of the absolute values;
- and
- (e) determining, based upon the determined mean value, the noise of the image;
- (f) sigma filtering the image, using the determined noise, to produce a sigma filtered input image;
- (g) analysis processing the sigma filtered input image to produce an approximation part and a detail part;
- (h) sigma filtering the approximation part to produce a sigma filtered approximation part;
- and
- (i) synthesizing the sigma filtered approximation part and the detail part to generate a reconstructed filtered image.
A system for improving the quality of a digital image comprising:
- a first filter to high pass filter the image data;
- a mean circuit, operatively connected to said first filter, to determine absolutes values of the high pass filtered image data and to determine a mean value of the absolute values;
- a noise level circuit, operatively connected to said mean circuit, to determine, based upon the determined mean value, the noise of the image;
- a first sigma filtering circuit, using the determined noise level, to sigma filter an image to produce a sigma filtered image;
- an analysis circuit to process the sigma filtered image to produce an approximation part and a detail part;
- a second sigma filter circuit to filter the approximation part to produce a sigma filtered approximation part;
- and
- a synthesizer to combine the sigma filtered approximation part and the detail part to generate a reconstructed filtered image.
Dependencies are inferred from the claim text.