Patent ID: 8194160

Claim:
An image processing system arranged to perform a gradation conversion on an image signal, the image processing system comprising: a frequency decomposition unit for decomposing the image signal into a high frequency component and a low frequency component; a high frequency separation unit for separating the high frequency component into an invalid component caused by noise and other valid component; a conversion characteristic calculation unit for calculating a conversion characteristic used for the gradation conversion on the basis of the low frequency component; a gradation processing unit for respectively performing gradation processing on the low frequency component and gradation processing on the valid component in the high frequency component by using the conversion characteristic, and respectively outputting the low frequency component on which the gradation processing has been performed and the valid component in the high frequency component on which the gradation processing has been performed; and a frequency synthesis unit for synthesizing the invalid component in the high frequency component, the low frequency component on which the gradation processing has been performed and the valid component in the high frequency component on which the gradation processing has been performed.