| 摘要 |
An apparatus for controlling a quantization step size for use in an encoder which divides one image frame into first blocks and encodes the divided first blocks and transmits the encoded data at a constant transmission rate. The apparatus includes a forward analyzer for detecting image complexity with respect to each first block to be quantized, a luminance analyzer for outputting a luminance value representative of each first block, a picture quality estimator for restoring quantized data by using a quantization step size corresponding to the quantized data and generating a judgement reference value corresponding to a minimum blocking effect which cannot be visually recognized on the basis of the restored data of every second block composed of first blocks, a buffer for storing the quantized data and outputting buffer occupancy of the stored data, a neural network having stored weight values which are updated according to the judgement reference value of the picture quality estimator with respect to the quantized previous second block and the stored update rule, generating a quantization step size for the present second block on the basis of the motion vectors, and/or the image complexity and/or the luminance values with respect to the present second block, the buffer occupancy and the updated weight values, and supplying the quantization step size to the picture quality estimator, and a quantizer for quantizing data of the second blocks encoded by the encoder according to a corresponding quantization step size supplied from the neural network.
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