| 摘要 |
PURPOSE:To control data quantity after compression so as to be a desired value by determining beforehand a data quantity function for every divided block of a picture, and comparing this data quantity function with cumulative data quantity obtained by compressing data actually for every block, and changing a control variable for every block. CONSTITUTION:Input picture data is divided into plural pXq-pieces of the blocks consisting of nXn-picture elements in a horizontal and a vertical directions per one block, and every block is applied two-dimensional discrete cosine transformation(DCT). The DCT factor of one picture portion stored in a memory is read out for every block, and is quantized by dividing it by a value obtained by multiplying each threshold of a quantize matrix consisting of nXn-pieces of the thresholds by a scale factor. The data quantity after compression of the picture data of a compressed one block portion is counted, and its cumulative data quantity Vs and the data quantity function Gs are compared with each other, and the control variable (k) in low pass filter processing is adjusted. |
