If a phone spec says that it has HDR display, does that mean the phone supports at least ARGBHalf or ARGBFloat render texture? or are they totally unrelated?
Also, does anybody know if I am targeting devices that only support ARGBHalf or ARGBFloat, just roughly how many phones on the market am I excluding?
HDR rendering and HDR display are related, but different.
HDR rendering is the GPU is rendering to a floating point render target, like using ARGBHalf or ARGBFloat (the later is unusual) so it can store values outside of the usual SDR 0.0 to 1.0 range.
An HDR display is one that can take an image that has data outside of the usual SDR 0.0 to 1.0 range, tonemap it to match the display’s capabilities. This requires that the application being run is able to output an HDR image.
Unity supports HDR rendering, it does not yet support HDR displays. It always internally tonemaps HDR rendered image to an SDR output.
Also, many devices are marketed as having an “HDR display”, but that just means it can receive an HDR image and display it properly. It does not mean the resulting image you see is any different than an SDR image! A lot of devices are advertising themselves as being HDR, but really they’re the same SDR displays that we had before, they can just take an HDR input and tonemap them back down to a 0.0 to 1.0 range. For PC monitors (or some TVs) you’ll usually see these displays listed as VESA DisplayHDR 400. That 400 means the display has a standard brightness of 400 nits, basically it’s a normal non-HDR SDR display that can take an HDR image signal.
Mobile devices are a total wild west. Several supposed HDR capable phones are still using “8 bit” panels. That’s a good sign that the HDR part is total bull.