lossless 16-Bit grayscale support

[kcco...@gmail.com]

Hi WebPers,

Sadly WebP does not yet support 16-bit grayscale images. Are there plans to ever support such a mode? How much work would be involved support 16-bit images? Are there minor changes that can be done to the library to get 16-bit images to work? or is the implementation designed only for 8-bit component images and there is no easy way around that?

Otherwise, can someone here recommend a transform that can be done on the image to split the 16-bit values into two 8-bit components so that it can be efficiently stored in the WebP container.?

Thanks,

Kal

[Brendan Bolles]

On Wednesday, April 6, 2016 at 2:48:52 AM UTC-7, kcco...@gmail.com wrote:

Hi WebPers,

Sadly WebP does not yet support 16-bit grayscale images. Are there plans to ever support such a mode?

I doubt there are plans. Do you have a web page that requires such an image?

I would suggest using PNG, which already does what you want.

Brendan

 

[Pascal Massimino]

Hi Kal,

On Wed, Apr 6, 2016 at 2:41 AM, <kcco...@gmail.com> wrote:

Hi WebPers,

Sadly WebP does not yet support 16-bit grayscale images. Are there plans to ever support such a mode? How much work would be involved support 16-bit images? Are there minor changes that can be done to the library to get 16-bit images to work? or is the implementation designed only for 8-bit component images and there is no easy way around that?

By design, WebP is not a  fit for hi-fidelity storage like 16b images. The format rather trying to stay close to the final display capabilities (especially on mobile devices) and rather trying to save on transfer rates. That's why 10bit or 16bit sample depth, float samples, HDR, CMYK, etc. are out of its scope for instance.

It would be hard to retrofit 16b support in it (there was such attempt quite some time ago, using multi-layers: storing the upper 8b of samples in a regular webp file, and then the lower 8b separately. But compression was difficult for this extra layer).

Otherwise, can someone here recommend a transform that can be done on the image to split the 16-bit values into two 8-bit components so that it can be efficiently stored in the WebP container.?

As Brendan mentioned, some image formats like PNG have better archival capabilities and are a better fit for 16b sources.

hope it helps!

skal/

 

[kcco...@gmail.com]

Hi skal,

Thanks for the detailed information. I am looking into other formats. I was mainly interested in WebP because of its compression ratio and speed.

Kal