Method for reducing color moiré in digital images
AssigneeJENOPTIK Laser, Optik, Systeme GmbH
InventorBurkhard Hahn
Life of this patent
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Abstract
In a method for reducing color moiré in digital images, the object is to improve the suppression of color moiré in such a way that effects on edge areas and fine structures are further reduced in that low-frequency beats causing color moiré are detected and attenuated in such a way that correction is carried out only for two-dimensionally extensive areas and the edge areas and fine structures remain excluded to a great extent. A comparison of bandpass energies between the luminance channel and chrominance channels serves as a marking criterion in order initially to determine pixels in which color moiré is present and then to carry out a frequency-selective energy reduction in the chrominance channels at middle frequencies for suppressing the long-wave color moiré.
Claims10
A method for reducing color moiré in digital images comprising the steps of:
- transforming the color signals of the image from an initial color space into a luminance channel and into chrominance channels of a luminance/chrominance color space in which the luminance channel remains free of color signals that are transformed into the chrominance channels;
- performing a bandpass splitting in the luminance and chrominance channels for intersecting the frequencies of the luminance and chrominance channels into several underfrequency ranges in the same manner;
- performing a comparison of energy values, pixel by pixel, between the luminance channel and the chrominance channels that is limited to first selected frequencies chosen from said underfrequency ranges in order to detect pixels in which color moiré is present when the energy value in the chrominance channel is greater than in the luminance channel;
- making a correction of the energy values of pixels, in which color moiré is detected, in at least one of the chrominance channels, wherein the correction is limited to second selected frequencies chosen from one of said underfrequency ranges;
- and
- transforming the corrected color signals of the chrominance channels and the color signals of the luminance channel back into the initial color space.
Dependencies are inferred from the claim text.