2 Commits

Author	SHA1	Message	Date
Nigel Tao	dbcdce5866	image/png: optimize paeth some more. ... filterPaeth takes []byte arguments instead of byte arguments, which avoids some redudant computation of the previous pixel in the inner loop. Also eliminate a bounds check in decoding the up filter. benchmark old ns/op new ns/op delta BenchmarkDecodeGray 3139636 2812531 -10.42% BenchmarkDecodeNRGBAGradient 12341520 10971680 -11.10% BenchmarkDecodeNRGBAOpaque 10740780 9612455 -10.51% BenchmarkDecodePaletted 1819535 1818913 -0.03% BenchmarkDecodeRGB 8974695 8178070 -8.88% R=rsc CC=golang-dev https://golang.org/cl/6243061	2012-05-30 21:38:46 +10:00
Nigel Tao	1423ecb126	image/png: optimize the paeth filter implementation. ... image/png benchmarks: benchmark old ns/op new ns/op delta BenchmarkPaeth 10 7 -29.21% BenchmarkDecodeGray 2381745 2241620 -5.88% BenchmarkDecodeNRGBAGradient 9535555 8835100 -7.35% BenchmarkDecodeNRGBAOpaque 8189590 7611865 -7.05% BenchmarkDecodePaletted 1300688 1301940 +0.10% BenchmarkDecodeRGB 6760146 6317082 -6.55% BenchmarkEncodePaletted 6048596 6122666 +1.22% BenchmarkEncodeRGBOpaque 18891140 19474230 +3.09% BenchmarkEncodeRGBA 78945350 78552600 -0.50% Wall time for Denis Cheremisov's PNG-decoding program given in https://groups.google.com/group/golang-nuts/browse_thread/thread/22aa8a05040fdd49 Before: 2.25s After: 2.27s Delta: +1% The same program, but with a different PNG input file (http://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png) and only 100 iterations instead of 1000 Before: 4.78s After: 4.42s Delta: -8% R=rsc CC=golang-dev https://golang.org/cl/6242056	2012-05-25 14:08:51 +10:00