| US 7,450,774 B2 | ||
| Method of changing bit rate by changing codeword of compressed image bit stream | ||
| Cheul-hee Hahm, Gyeonggi-do (Korea, Republic of); and Jae Moon Jo, Gyeonggi-do (Korea, Republic of) | ||
| Assigned to Samsung Electronics Co., Ltd., Suwon-Si (Korea, Republic of) | ||
| Filed on Apr. 22, 2002, as Appl. No. 10/126,981. | ||
| Claims priority of application No. 2001-47141 (KR), filed on Aug. 04, 2001. | ||
| Prior Publication US 2003/0026491 A1, Feb. 06, 2003 | ||
| Int. Cl. G06K 9/00 (2006.01); G06K 9/36 (2006.01); G06K 9/46 (2006.01); H04N 1/41 (2006.01); H04N 1/413 (2006.01) | ||
| U.S. Cl. 382—245 [382/166; 358/426.13; 358/426.14] | 7 Claims |
| 1. An apparatus for changing a bit rate, in which an input bit stream generated by an image compression encoding method is
changed into an output bit stream having a desired bit rate, the apparatus comprising:
a changing codeword determiner to select a candidate codeword for each codeword in the input bit stream, each codeword having
a run length and a level for transform coefficients; and
a codeword changer to selectively change each codeword of the input bit stream into the candidate codeword selected by the
changing codeword determiner based on a determination that a number of bits can be reduced by using the candidate codeword
in the output bit stream,
wherein the changing codeword determiner selects as the candidate codeword shortest one of the candidate codewords satisfying
two requirements: (1) having a same run length that of the codeword in the input stream, and (2) having a level less than
that of the codeword in the input stream by a preset value,
wherein the changing codeword determiner and the codeword changer repeat codeword selection and codeword changing for the
output bit stream,
after increasing the preset value by 1 for each repetition, until the desired bit rate is satisfied.
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