| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide transcoding techniques for compressing image data to a reduced size. <P>SOLUTION: An encoding device scales one or more quantization tables as a function of the near linear relationship between bitrate (R) and the number of zero-valued quantized transform coefficients to reduce the file size uniformly over the entire image. Then the device encodes a plurality of blocks of pixels using the scaled quantization tables. At this time, the device tracks a difference between the number of bits encoded at an nth block of the plurality of blocks of pixels and the number of bits that ideally should be encoded at the nth block to achieve a target bitrate, and removes one or more bits used to encode a portion of the plurality of blocks when the difference is greater than or equal to a threshold. <P>COPYRIGHT: (C)2013,JPO&INPIT |
