IMAGE ENCODING METHOD,AND IMAGE DEVICE

摘要

An image encoding method and an image device effective for a large number of applications without requesting any changes on the decoding side by allowing the encoding side to have processing for reducing noise generation.A pixel of gradation value of 255 corresponding to white is changed to the value outside the gradation range in the direction opposite to black.This means that the value is set to be much larger than the gradation value of 255 which is the maximum white in the color expression.The image subjected to gradation shifting is encoded to generate a ripple(31)which is larger than the gradation value of 255 in the white part of the image.However,the abnormal state of the ripple−like image in the decoded image before clipping is formed around the gradation value higher than the gradation value of 255.Thus,mosquito noise is generated in a part having the gradation value outside the gradation range higher than the gradation value of 255.The mosquito noise can be reduced by clipping this image by the gradation value of 255.