Re: RFR: 8300725: Improve performance of ColorConvertOp for default destinations with alpha

[Laurent Bourgès]

On Fri, 20 Jan 2023 06:02:53 GMT, Sergey Bylokhov <s...@openjdk.org> wrote:

> The "default destination" for the ColorConverOp is used when the user passes 
> "null" as the DST parameter. In this case, the "ColorConverOp.filter" creates 
> the default image and uses ComponentColorModel: 8 bits per color component 
> and optionally 8 bits for the alpha channel. For example for the ARGB source 
> default destination will be RGBA format. Note that the RGBA format is not 
> supported by BufferedImage directly, so the CUSTOM image type will be used.
> 
> Generic filtering of the CUSTOM image type is slow because we cannot pass 
> that format directly to the CMM. But it would be good to support CUSTOM 
> images that were created by the ColorConverOp.
> 
> Support of the default destination w/o alpha was implemented as part of the 
> https://bugs.openjdk.org/browse/JDK-8005530. Since then we added support of 
> the alpha to CMM code https://bugs.openjdk.org/browse/JDK-8012229.
> Now we can improve the performance of the default destination if it has the 
> alpha channel.
> 
> The numbers for filtering opaque and transparent images to the null 
> destination:
> <img width="705" alt="8300725" 
> src="https://user-images.githubusercontent.com/14138494/213744370-241726f9-6653-403e-bb90-ce98fc089945.png";>

Congratulations, it is amazing!

Would it be possible to add support for INT_BGRA_PREMUL as supported by skia 
default raster N32 format?

Of course I cab help but not alone as it means many changes in C macros & 
backends + CSR request ...

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PR: https://git.openjdk.org/jdk/pull/12110