| 摘要 |
PURPOSE: To obtain a field correlation detector, a coder and its method by which a coefficient in a high frequency range is reduced. CONSTITUTION: The coder is provided with an 8×8 picture element block processing circuit 1, a processing selection circuit 2, an orthogonal transformation circuit 3, an adder/subtractor 8, an absolute value circuit 9, a comparator 10, a buffer memory 11, an 8×8 picture element DCT circuit 12 for implementing frame processing, a 4×8 picture element DCT circuit 13 for implementing field processing, a selector 14, a threshold level decision circuit 17, and a maximum value circuit 18. When data subjected to block processing into 8×8 picture elements are given to a processing selection circuit 2, the absolute value of the field difference is calculated by the adder subtractor 8 and the absolute value circuit 9. The maximum value circuit 18 detects a maximum value of an absolute value to be calculated and provides an output of comparison information between the maximum value of the absolute value and the threshold level TH. The selector 14 selects one DCT circuit in two kinds of DCT processing based on the comparison information. As the absolute value is larger, the correlation is smaller, and when orthogonal transformation is applied to a block having a motion, the DCT coefficient is set to a lower band more by 4×8 picture element DCT processing and it is preferred from the standpoint of coding efficiency. |
