So, let’s say I found that reference photo online and I would like to use for texturing or anything relevant in a Scene-Referred workflow:
This Output-Referred image has been rendered in a way or another to be pleasing on a particular display, e.g. S-Curve, contrast, saturation tweaks, you name it.
Now, and keeping in mind that the bottom left swatch (White 9.5 (.05 D)) reflectance should be around 91% , if I use the
Output - sRGB as input transform to linearise the image, i.e. put it in Scene-Referred state, this swatch that was around 93% is now jumping to around 320% reflectance!
Because anyone paying attention to details will tell me that I should make sure that the Neutral 5 (.70 D) swatch (third from the bottom right) stays around 19%, I thus expose down the image accordingly:
What we see here is that the White 9.5 (.05 D) swatch is still well above 100%, i.e. 120%, and that the blacks are completely crushed.
At this point it is pretty much game over. You will need to massage your imagery until you find a sweet spot where it feels right and usable.
Hope that helps,