"On these non-HDR displays, Apple has remapped “white” to something less than 255-255-255, leaving headroom for HDR vales, should they be called for"
What is the source for this? I don't see any justification for this claim in the article. There are plenty of ways to implement this feature that don't involve permanently throwing out dynamic range on all your SDR panels. I'm not even convinced from reading this that they aren't HDR panels to begin with - the idea of an iPhone having a 9-bit or 10-bit panel in it isn't that strange to me, and while that wouldn't be enough for like Professional-Grade HDR it's enough that you could pair it with dynamic backlight control and convince the average user that it's full HDR.
Considering Apple controls the whole stack and uses a compositor there's nothing stopping them from compositing to a 1010102 or 111110 framebuffer and then feeding that higher-precision color data to the panel and controlling the backlight. Since they control the hardware they can know how bright it will be (in nits) at various levels.
What is the source for this? I don't see any justification for this claim in the article. There are plenty of ways to implement this feature that don't involve permanently throwing out dynamic range on all your SDR panels. I'm not even convinced from reading this that they aren't HDR panels to begin with - the idea of an iPhone having a 9-bit or 10-bit panel in it isn't that strange to me, and while that wouldn't be enough for like Professional-Grade HDR it's enough that you could pair it with dynamic backlight control and convince the average user that it's full HDR.
Considering Apple controls the whole stack and uses a compositor there's nothing stopping them from compositing to a 1010102 or 111110 framebuffer and then feeding that higher-precision color data to the panel and controlling the backlight. Since they control the hardware they can know how bright it will be (in nits) at various levels.