摘要 |
Methods, machines, systems and machine-readable instructions for processing an image are described. In one aspect, the image is divided into a population of image blocks. Frequency domain vectors are generated from respective ones of the image blocks. Each of the frequency domain vectors includes a respective set of values corresponding to a set of transform coefficients. Preliminary estimates of quantization parameter values are determined from frequency distributions of the transform coefficient values in a set of the frequency domain vectors corresponding to a variable sample of the population. The variable sample is determined at least in part by at least one threshold. Values of quantization parameters are estimated from the preliminary estimates.
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