Mercurial > hg > pydct
view pydct/perceptual.py @ 0:63af49cca5d2
initial import
| author | pmeerw@pan |
|---|---|
| date | Tue, 06 May 2008 23:01:28 +0200 |
| parents | |
| children | 8981e90540bf |
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import numpy JPEG_luma_Q = numpy.array( [[16, 11, 10, 16, 24, 40, 51, 61], [12, 12, 14, 19, 26, 58, 60, 55], [14, 13, 16, 24, 40, 57, 69, 56], [14, 17, 22, 29, 51, 87, 80, 62], [18, 22, 37, 56, 68, 109, 103, 77], [24, 35, 55, 64, 81, 104, 113, 92], [49, 64, 78, 87, 103, 121, 120, 101], [72, 92, 95, 98, 112, 100, 103, 99]]) JPEG_chroma_Q = numpy.array( [[17, 18, 24, 47, 99, 99, 99, 99], [18, 21, 26, 66, 99, 99, 99, 99], [24, 26, 56, 99, 99, 99, 99, 99], [47, 66, 99, 99, 99, 99, 99, 99], [99, 99, 99, 99, 99, 99, 99, 99], [99, 99, 99, 99, 99, 99, 99, 99], [99, 99, 99, 99, 99, 99, 99, 99], [99, 99, 99, 99, 99, 99, 99, 99]]) def watson_slack(b, c00): # table of sensitivity values t = numpy.array( \ [1.404, 1.011, 1.169, 1.664, 2.408, 3.433, 4.796, 6.563,\ 1.011, 1.452, 1.323, 1.529, 2.006, 2.716, 3.679, 4.939,\ 1.169, 1.323, 2.241, 2.594, 2.988, 3.649, 4.604, 5.883,\ 1.664, 1.529, 2.594, 3.773, 4.559, 5.305, 6.281, 7.600,\ 2.408, 2.006, 2.988, 4.559, 6.152, 7.463, 8.713, 10.175,\ 3.433, 2.716, 3.649, 5.305, 7.463, 9.625, 11.588, 13.519,\ 4.796, 3.679, 4.604, 6.281, 8.713, 11.588, 14.500, 17.294,\ 6.563, 4.939, 5.883, 7.600, 10.175, 13.519, 17.294, 21.156]) tl = t * math.pow(b.ravel()[0] / c00, 0.649) tl[1:] = numpy.maximum(tl[1:], (numpy.abs(b.ravel()[1:])**0.7) * (tl[1:]**0.3)) return tl.reshape((8, 8))