Question regarding power consumption about dwm_lut

[ledoge]

Great question – this tool works by copying the pixels that DWM is about to send to the screen to a separate texture, then writing them back with the color transform applied. This copy process takes up quite a bit of VRAM bandwidth and therefore also power. The cost of actually applying the LUT and dithering is negligible in comparison.

In theory, it should be possible to hook into DWM in a different way with less of a performance impact. E.g. Windows has built-in color filters that can be enabled with, as far as I can tell, pretty much no performance impact. Without having access to the DWM source code, integrating it similarly to that would probably be quite difficult – I looked into it for a bit and didn't really get anywhere.

GPU drivers can do all kinds of transforms pretty much for free as part of the graphics pipeline, since they have full control over it. Hooking into that would probably require a huge amount of effort and a custom driver – though I don't know too much about how GPUs work, so this could be wrong. Interestingly, it seems that programs like Dell PremierColor and MSI True Color use the 3D LUT support built into Intel's iGPU drivers – no idea if this functionality could be used differently to avoid posterization/banding though.