Use fewer multiplications in JpegImage._convertCmykToRgb
#11547
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*Note:* This is inspired by PR 5473, which made similar changes for another kind of JPEG data. Since the implementation in `src/core/jpg.js` only supports 8-bit data, as opposed to similar code in `src/core/colorspace.js`, the computations can be further simplified since the `scale` is always constant. By updating the coefficients, effectively inlining the `scale`, we'll thus avoid *four* multiplications for each loop iteration. Unfortunately I wasn't able, based on a quick look through the test-files, to find a sufficiently *large* CMYK JPEG image in order for these changes to really show up in benchmark results. However, when testing the `cmykjpeg.pdf` manually there's a total of `120 000` fewer multiplication with this patch.
From: Bot.io (Linux m4)ReceivedCommand cmd_test from @Snuffleupagus received. Current queue size: 0 Live output at: http://54.67.70.0:8877/a3708a4957c505a/output.txt |
From: Bot.io (Windows)ReceivedCommand cmd_test from @Snuffleupagus received. Current queue size: 0 Live output at: http://54.215.176.217:8877/58a39edf51d6bc0/output.txt |
From: Bot.io (Windows)FailedFull output at http://54.215.176.217:8877/58a39edf51d6bc0/output.txt Total script time: 2.20 mins
Image differences available at: http://54.215.176.217:8877/58a39edf51d6bc0/reftest-analyzer.html#web=eq.log |
From: Bot.io (Linux m4)FailedFull output at http://54.67.70.0:8877/a3708a4957c505a/output.txt Total script time: 19.51 mins
Image differences available at: http://54.67.70.0:8877/a3708a4957c505a/reftest-analyzer.html#web=eq.log |
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@brendandahl Could you perhaps fix the Windows bot failure? |
From: Bot.io (Linux m4)ReceivedCommand cmd_test from @Snuffleupagus received. Current queue size: 1 Live output at: http://54.67.70.0:8877/04e30cc3b427165/output.txt |
From: Bot.io (Windows)ReceivedCommand cmd_test from @Snuffleupagus received. Current queue size: 0 Live output at: http://54.215.176.217:8877/e9ef699baeeb549/output.txt |
From: Bot.io (Windows)FailedFull output at http://54.215.176.217:8877/e9ef699baeeb549/output.txt Total script time: 26.21 mins
Image differences available at: http://54.215.176.217:8877/e9ef699baeeb549/reftest-analyzer.html#web=eq.log |
From: Bot.io (Linux m4)FailedFull output at http://54.67.70.0:8877/04e30cc3b427165/output.txt Total script time: 19.74 mins
Image differences available at: http://54.67.70.0:8877/04e30cc3b427165/reftest-analyzer.html#web=eq.log |
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Good idea! |
Note: This is inspired by PR #5473, which made similar changes for another kind of JPEG data.
Since the implementation in
src/core/jpg.jsonly supports 8-bit data, as opposed to similar code insrc/core/colorspace.js, the computations can be further simplified since thescaleis always constant.By updating the coefficients, effectively inlining the
scale, we'll thus avoid four multiplications for each loop iteration.Unfortunately I wasn't able, based on a quick look through the test-files, to find a sufficiently large CMYK JPEG image in order for these changes to really show up in benchmark results. However, when testing the
cmykjpeg.pdfmanually there's a total of120 000fewer multiplication with this patch.