| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image coding apparatus capable of preventing the impairment of sharpness caused by the sharp decrease of the number of bits which can be assigned and the sudden change of a frame rate, in a case that scenes difficult to be coded are continued. <P>SOLUTION: A deriving part 31 for deriving the frame constellation target number of bits which can be assigned reads out from a memory 36 the total number of bits of frame constellation units to remaining frames, subtracts the generating number of bits used by coding the previous frames and updates, and transmits it to a deriving part 32 for deriving the following frame target number of bits. The deriving part 32 for deriving the following frame target number of bits computes the target number of bits assigned to the following frames based on the remaining frame number in consideration of the received total number of bits and frame rate values Rf. A deriving part 33 for deriving the mean or average frame number of bits computes the mean rate of the number of bits assigned to the former frames. An operation part 34 multiplies the mean rate of the computed number of bits by considered factors, compares this with a target value of the number of bits, and selects a greater one of values and transmits it to a deriving part 35 for a quantization step. <P>COPYRIGHT: (C)2004,JPO |
