Nixon & Vanderhye, PC
Image encoding method and image apparatus
An object of the invention is to provide an image encoding method and an image apparatus which do not request change on a decoder and can give effects on many applications by having an encoder carry processing for reducing occurrence of noise. A pixel whose tone value is 255 and corresponds to white is changed to a value outside of an extent of the tone value in the inverse direction for black, in other words to a value more than the whitest tone value 255. When an image for which this tone shifting processing is performed is encoded and decoded, a ripple 31 having a larger tone value than 255 occurs in a white portion of the image. Abnormal condition of the image in a shape of ripple on the decoded image existing prior to clipping is centered in a tone value larger than 255. Accordingly, mosquito noise occurs in a portion with a tone value larger than 255 and outside of an extent of the tone value. When this image is clipped by the tone value 255, the mosquito noise can be reduced.
Sharp Kabushiki Kaisha
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Hideaki
Yamada