We propose a new method for requantizing JPEG images, based on the well-known Laplacian distribution of the AC discrete cosine transform (DCT) coefficients and on an analysis of the error introduced by requantization. The resulting images have improved perceptual image quality over a “blind” requantization approach, that is, one that does not consider the properties of the quantization matrices.
['Heinz H. Bauschke', 'Chris H. Hamilton', 'Mason S. Macklem', 'Justin S. McMichael', 'Nicholas R. Swart']
A requantization-based method for recompressing JPEG images