On Donnerstag, 21. April 2022 08:43:38 CEST Andreas Kemnade wrote:

On Wed, 13 Apr 2022 17:19:00 -0500
Samuel Holland [off-list ref] wrote:

quoted

Blitting/Blending in Software
=============================
There are multiple layers to this topic (pun slightly intended):
 1) Today's userspace does not expect a grayscale framebuffer.
    Currently, the driver advertises XRGB8888 and converts to Y4
    in software. This seems to match other drivers (e.g. repaper).

 2) Ignoring what userspace "wants", the closest existing format is
    DRM_FORMAT_R8. Geert sent a series[4] adding DRM_FORMAT_R1 through
    DRM_FORMAT_R4 (patch 9), which I believe are the "correct" formats
    to use.

hmm R=red? That sounds strange. I am unsure whether doing things with
lower bit depths actually really helps. 

Hi,

for single-component formats, the name of the component plays
practically no role. Even if said component was really red,
it makes little difference to either side.

For example, the OpenGL straight up refers to all single component
image formats as only using the red component:

	OpenGL only allows "R", "RG", "RGB", or "RGBA"; other
	combinations are not allowed as internal image formats.

from https://www.khronos.org/opengl/wiki/Image_Format

In truth it would of course be nice if the world agreed on
not making the name of data structures imply some way they
are to be processed, but humanity hasn't gotten there yet.

Regards,
Andreas

Regards,
Nicolas Frattaroli



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