Optimum Relations Between Image Quality, Pixel Resolution and Compression Ratio for High Quality Full-Color Images
1993 Volume 32 Issue 2 Pages 94-99
Details
1993 Volume 32 Issue 2 Pages 94-99
It is shown that optimum combinations of JPEG compression ratio and pixel resolution exist that yield peak image quality. Five test images, identical in content but different in pixel resolution, are evaluated by subjective opinion tests. For a compressed file size of320kBytes,the optimum image quality (MOS > 4) is achieved when the pixel resolution is 1024 × 1280and the compression ratio is 1/16. For 80 kByte files, peak quality (MOS < 2) is achieved at 512 × 640 pixels and a 1/16 compression ratio. This effect is thought to be due to the combination of two factors: the nonlinearity of the JPEG coding scheme and the perception of image quality as a nonlinear function of pixel resolution.
