[cairo] 16-bit, HDR and colour

Carl Worth cworth at cworth.org
Wed Oct 3 08:41:00 PDT 2007

On Wed, 3 Oct 2007 14:27:40 +0200 (CEST), Kai-Uwe Behrmann wrote:
> What I still was searching for, is a API in Cairo to set and get the image
> data types.

Cairo's currently supports a very limited set of image formats, (1
bit-per-pixel, 8 bits-per-pixel, 24 of 32-bit-per-pixel, and 32
bits-per-pixel), and all integer, (or fixed-point depending on how you
look at it).

> A buffer containing image data holds in most cases 16-bit ints per channel
> data for my use. Sometimes I'd need 16 and 32-bit floats.

It would definitely be nice to see cairo extended to have higher
bit-depth and floating-point image surfaces. That doesn't exist now. I
think a great way to get there would be one of the projects to make
pixman use dynamic compilation, (such as the jitblt work).

> Does all surfaces support higher bit depths or only a few?

I don't know of any currently. There's definitely not any code in
cairo itself, nor in pixman, for this. So if there is any possibility
of getting at this functionality with cairo it would have to be
through display-system-specific, (X, Quartz, win32), surfaces. But
even then, I don't know of anything that exists there either.

It's definitely an interesting direction to go, and I'd love to see
cairo go there. Would you be interested in helping to make that

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