On Mon, 29 Mar 2021 07:36:35 GMT, Sergey Bylokhov <s...@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 src/java.desktop/share/classes/sun/java2d/cmm/lcms/LCMSTransform.java line 167: > 165: return dst.getColorModel().hasAlpha() == > src.getColorModel().hasAlpha(); > 166: } > 167: Thoughts about the method above: - I have left the first check as-is, so for any opaque destinations we will pass data to the lcms directly, but I am not sure that this is correct for source/destination with premultiplied alpha. - Since I am not sure about premultiplied alpha I have excluded it for the current fix if the destination has an alpha channel. src/java.desktop/share/native/liblcms/LCMS.c line 193: > 191: > 192: sTrans = cmsCreateMultiprofileTransform(iccArray, j, > 193: inFormatter, outFormatter, renderType, cmsFLAGS_COPY_ALPHA); Does not affect performance if the image does not have alpha. test/jdk/sun/java2d/cmm/ColorConvertOp/ColCvtAlphaDifferentSrcDst.java line 73: > 71: //opaqueDst(TYPE_INT_ARGB_PRE, TYPE_4BYTE_ABGR_PRE); > 72: //opaqueDst(TYPE_4BYTE_ABGR_PRE, TYPE_INT_BGR); > 73: } Actually, according to the spec, we should transform pre-alpha to alpha -> then apply ICC transform -> then transform pre-alpha-> alpha. See class description of the: https://docs.oracle.com/javase/7/docs/api/java/awt/image/ColorConvertOp.html But it looks like implementation does something different. ------------- PR: https://git.openjdk.java.net/jdk/pull/3239
