In a modern image chain, capture is more often than not HDR.
These images are then graded for HDR or SDR. I.e., sacrifices are made on the image data such that it is suitable for a display standard.
If you have an HDR image, it's relatively easy to tone-map that into SDR space, see e.g. BT.2408 for an approach in Video.
The underlying problem here is that the Web isn't ready for HDR at all, and I'm almost 100% confident browsers don't do the right things yet. HDR displays have enormous variance. From "Slightly above SDR" to experimental displays at Dolby Labs. So to display an image correctly, you need to render it properly to the displays capabilities. Likewise if you want to display a HDR image on an SDR monitor. I.e., tone mapping is a required part of the solution.
A correctly graded HDR image taken of the real world will have like 95% of the pixel values falling within your typical SDR (Rec.709/sRGB) range. You only use the "physically hurt my eyes" values sparingly, and you will take the room conditions into consideration when designing the peak value. As an example: cinemas using DCI-P3 peaks at 48 nits because the cinema is completely dark. 48 nits is more than enough for a pure white in that environment. But take that image and put it on a display sitting inside during the day, and it's not nearly enough for a white. Add HDR peaks into this, and it's easy to see that in a cinema, you probably shouldn't peak at 1000 nits (which is about 4.x stops of light above the DCI-P3 peak). In short: your rendering to the displays capabilities require that you probe the light conditions in the room.
It's also why you shouldn't be able to manipulate brightness on an HDR display. We need that to be part of the image rendering chain such that the right decisions can be made.
These images are then graded for HDR or SDR. I.e., sacrifices are made on the image data such that it is suitable for a display standard.
If you have an HDR image, it's relatively easy to tone-map that into SDR space, see e.g. BT.2408 for an approach in Video.
The underlying problem here is that the Web isn't ready for HDR at all, and I'm almost 100% confident browsers don't do the right things yet. HDR displays have enormous variance. From "Slightly above SDR" to experimental displays at Dolby Labs. So to display an image correctly, you need to render it properly to the displays capabilities. Likewise if you want to display a HDR image on an SDR monitor. I.e., tone mapping is a required part of the solution.
A correctly graded HDR image taken of the real world will have like 95% of the pixel values falling within your typical SDR (Rec.709/sRGB) range. You only use the "physically hurt my eyes" values sparingly, and you will take the room conditions into consideration when designing the peak value. As an example: cinemas using DCI-P3 peaks at 48 nits because the cinema is completely dark. 48 nits is more than enough for a pure white in that environment. But take that image and put it on a display sitting inside during the day, and it's not nearly enough for a white. Add HDR peaks into this, and it's easy to see that in a cinema, you probably shouldn't peak at 1000 nits (which is about 4.x stops of light above the DCI-P3 peak). In short: your rendering to the displays capabilities require that you probe the light conditions in the room.
It's also why you shouldn't be able to manipulate brightness on an HDR display. We need that to be part of the image rendering chain such that the right decisions can be made.