Thanks for this, the part about “absolute luminance” is pretty helpful!
So what you’re saying is that with hdr, whoever creates the video, adds to it absolute brightness levels for some/(all?) pixels, and then an HDR-capable screen would be a screen that has an api like ‘draw_pixel(x,y,color,absolute_luminance_in_nits)’ whereas an SDR screen would instead have ‘draw_pixel(x,y,color,relative_luminance)’ with relative_luminance in range [0,1] ?
I can imagine how the monitor brightness control would work in SDR, but what about HDR? If I lower the screen brightness, and the screen is asked to draw a pixel at 900 nits, what happens?
For a real use-case, suppose I want to watch an hdr movie on my MacBook - should I switch the display mode to “HDR Video (P3-ST 2084)” which is one of the presets that locks the display to a specific brightness?
So what you’re saying is that with hdr, whoever creates the video, adds to it absolute brightness levels for some/(all?) pixels, and then an HDR-capable screen would be a screen that has an api like ‘draw_pixel(x,y,color,absolute_luminance_in_nits)’ whereas an SDR screen would instead have ‘draw_pixel(x,y,color,relative_luminance)’ with relative_luminance in range [0,1] ?
I can imagine how the monitor brightness control would work in SDR, but what about HDR? If I lower the screen brightness, and the screen is asked to draw a pixel at 900 nits, what happens? For a real use-case, suppose I want to watch an hdr movie on my MacBook - should I switch the display mode to “HDR Video (P3-ST 2084)” which is one of the presets that locks the display to a specific brightness?