Monochrome/greyscale and software dithering in the kernel

[David Lechner]

On 08/03/2017 09:58 AM, Noralf Trønnes wrote:
> Hi,
> 
> The tinydrm/repaper driver is monochrome, but I have just used an
> emulation format XRGB8888, since monochrome support is scarce in
> userspace. I'm using ITU BT.601 to convert from rgb to greyscale and
> then use the msb for monochrome.
> 
> Now I'm asked if we can implement Floyd–Steinberg dithering in the driver
> to make it more useful, so userspace can work reasonably well with
> default tools/libs. I did have that in the first stage of the driver
> development, but decided against it, since I figured this was the
> responsibility of userspace not the kernel. But personally it doesn't
> really matter to me either way.
> 
> So the question is, can I say yes to such an addition?
> 

IMHO, if we add monochorme/grayscale support to DRM, then I think using 
dithering for the "compatibility mode" XRGB8888 emulation would be a 
good idea. But until then, I don't think I would like it because unless 
you are displaying photos it will probably causes some noticeable 
distortion.