Patent ID: 7692817
Filing Date: 2010-04-06
Classification: H04N

Abstract:
1. An image processing method for carrying out image processing by transforming image data to image data having spatial frequency components and by modifying the coefficients of said spatial frequency components, comprising steps controlled by a processor of: judging whether at least one of absolute values of the products obtained by multiplying the plural coefficients of the predetermined frequency components, corresponding to a predetermined direct current component, of the transformed image data by the coefficients of the direct current (DC) components of the same is equal to or more than a predetermined value, wherein a plurality of the absolute values correspond with each of the plural coefficients and the absolute values correspond with the direct current component; modifying the coefficients of alternating current (AC) components of said image data by calculation depending on the result of the judgment; adding specific values to the modified coefficients of the alternating current (AC) components of the image data; inversely transforming the image data, to which said specific values are added, to image data having spatial coordinate components; comparing gray levels of the inversely transformed image data with predetermined values; and transforming said gray levels to quantized levels corresponding to the result of the comparison, wherein all the coefficients of the alternating current components corresponding to the predetermined direct current component are modified by calculation, once the judging has been carried out.