| 摘要 |
PURPOSE: To provide moving images with high efficiency and high picture quality by selecting any effective quantizer based on human visual characteristics and encoding efficiency through a method and a circuit for quantization. CONSTITUTION: At a moving image compression circuit, line subsampling is performed to color difference signals in the elements of 4:2:2 format, namely, the input signals of Y: 720 pixels × 480 lines and Cr, Cb: 360 pixels × 480 lines and after the format is transformed to 4:2:0, these signals are used as an input signal source at an encoding part. The update unit of quantizer is set to one macro block, namely, Y: 16 pixels × 16 lines and Cr, Cb: 8 pixels ×8 lines and ratio control and forward estimation are performed to the quantizer. In the forward estimation, the moving image signal is sorted in a spatial area while considering the human visual characteristics and the quantizer corresponding to one macro block is selected through a final tuning process for a reference quantizing step size generated under the ratio control with a change degree, which utilizes a DCT coefficient to be encoded, as a parameter while considering encoding efficiency. |
