IMAGE ENCODER AND IMAGE DECODER

摘要

PROBLEM TO BE SOLVED: To prevent an image from deteriorating in accordance with the state of a transmission medium by adding information notifying that encoding is aborted to the encoded code and outputting it when the encoding from an upper bit of plural conversion coefficients which convert an original image is aborted at a halfway bit. SOLUTION: A sequential converting means 4 divides image data into a low frequency component band and a high frequency component band which consist of plural conversion coefficients. A conversion coefficient encoding means 5 performs reversible encoding of all of the conversion coefficients about the low frequency component, encodes the absolute value of the conversion coefficients and sign bit about the high frequency component, adds the end marker code and line number marker code of coded data and outputs them. A conversion coefficient decoding means 6 decodes high frequency component coded data based on information that is added to the coded data. A conversion coefficient correcting means 7 gets a conversion coefficient that is close to a true value and a correction conversion coefficient. An inverse converting means 8 performs inverse conversion of the correction conversion coefficient and outputs a reproduced image.