Patent ID: 7079698
Filing Date: 2006-07-18
Classification: G06T

Abstract:
1. An image decoding apparatus for restoring image data by decoding an entropy code to generate a coefficient relating to the image data, the entropy code being a bit pattern of which bit length is variable depending on occurrence probability of the coefficient, the image decoding apparatus comprising: a code string storing unit operable to store a code string including an entropy code, the entropy code being generated by coding a coefficient relating to image data; a decoding table containing a coefficient corresponding to an entropy code; a code specifying table containing entry information showing an entropy code corresponding to a coefficient, the entry information including compressed information and uncompressed information, the compressed information being generated by run-length compressing a part of the entropy code and showing a bit length of the run-length compressed part, and the uncompressed information showing another part of the entropy code aside from the run-length compressed part; a run-length obtaining unit operable to obtain a run-length of a run included in the code string, the run being a bit string of consecutive, same sign bits starting from a predetermined bit location; a bit length obtaining unit operable to obtain from the code specifying table uncompressed information corresponding to compressed information showing a same bit length as the obtained run-length; a specifying unit operable to specify, as the entropy code, a bit string that starts from the predetermined bit location and that has a length determined based on the obtained run-length and the length shown by the obtained uncompressed information; and a decoding unit operable to obtain from the decoding table a coefficient corresponding to the specified entropy code.