- This topic has 7 replies, 2 voices, and was last updated 5 years, 2 months ago by
.
-
Posts
-
I’m trying to understand the content colorspace setting. If the encoded content is limited to DCI P3 then why to choose BT.2020 as the source profile? In fact a BT. 2020 to Rec709 matrix transform gives similar results as a LUT with the same settings, which suggests that the encoded content is BT.2020 and the DCI P3 metadata is just informative of the mastering display colorspace. But then, how can this information be of any help?
I’m trying to understand the content colorspace setting. If the encoded content is limited to DCI P3 then why to choose BT.2020 as the source profile?
Because the content colorspace is encoded within the source colorspace container (i.e. DCi-P3 within Rec. 2020).
In fact a BT. 2020 to Rec709 matrix transform gives similar results as a LUT with the same settings, which suggests that the encoded content is BT.2020 and the DCI P3 metadata is just informative of the mastering display colorspace.
Correct.
But then, how can this information be of any help?
It’s currently only really affecting non colorimetric rendering intents (e.g. perceptual, saturation).
Maybe it’s a very technical question, but could you explain a little bit in which way it affects the non colorimetric rendering intents?
Not that I’m afraid if your answer is very technical. Sorry but it’s been a long time trying to understand this.
If you compress the whole Rec. 2020 space, this leads to a lot of compression being applied due to it being so huge. But if you assume that only a portion of it is used (i.e. the content colorspace), and only compress that, you end up with needing less compression.
Gamut compression happens during gamut mapping, i.e. mapping a larger colorspace (e.g. source colorspace) into a smaller one (e.g. a display colorspace). While colorimetric is used for reproducing colors exactly (and thus has to clip colors that are out of gamut), perceptual aims for maintaining the relation of colors to one another to generate a pleasing rendering (colors that are in-gamut will be mapped 1:1 if possible, everything else will be compressed).
So it’s the intensity of the compression applied. Thank you very much for your answer, I think I finally got it.
