[OpenJDK 2D-Dev] RFR: 8012229: [lcms] Improve performance of color conversion for images with alpha channel

[Alexander Zvegintsev]

On Mon, 29 Mar 2021 07:36:35 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

> The lcms 2.8 version added support for the cmsFLAGS_COPY_ALPHA flag:
> https://sourceforge.net/p/lcms/mailman/lcms-user/thread/001c01d1c0f3%2484a7cb30%248df76190%24%40ProDigitalSoftware.com/#msg35143398
> 
> which supports alpha channel transportation
> 
> For our usage, it means we can use TYPE_4BYTE_ABGR and TYPE_INT_ARGB directly as a source and destination.
> 
> Some numbers:
> converting new BufferedImage(3000, 3000, TYPE_INT_ARGB) from CS_sRGB to CS_CIEXYZ via op.filter(src, dst).
> //before the fix
> //Benchmark                  Mode  Cnt    Score    Error  Units
> //ColorAlphaConv.testFilter  avgt    5  603,392 ± 12,932  ms/op
> 
> //after the fix
> //Benchmark                  Mode  Cnt    Score   Error  Units
> //ColorAlphaConv.testFilter  avgt    5  121,624 ± 0,906  ms/op
> 
> But still slower than kcms
> //kcms jdk8u60
> //Benchmark                  Mode  Cnt   Score   Error  Units
> //ColorAlphaConv.testFilter  avgt    5  13,256 ± 0,169  ms/op

Marked as reviewed by azvegint (Reviewer).

test/jdk/sun/java2d/cmm/ColorConvertOp/ColCvtAlphaDifferentSrcDst.java line 52:

> 50: 
> 51:     private static int WIDTH = 256;
> 52:     private static int HEIGHT = 256;

Basing on naming, it looks that you wanted to make these variable final.

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PR: https://git.openjdk.java.net/jdk/pull/3239