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Which color space does DS use for non spectral exr output ?

cgidesigncgidesign Posts: 442
in Technical Help (nuts n bolts)

DS 4.16

Tonemapping = off

Spectral rendering = off

Render to 32 bit exr canvas (beauty)

What color space does DS use in this case?

E.g. sRGB, REC709, eciRGB etc.?

When spectral is on, one can decide in the drop down list, but not when spectral is off.

Comments

  • Richard HaseltineRichard Haseltine Posts: 100,739

    I don't think it is doing anything but linear RGB.

  • cgidesigncgidesign Posts: 442

    Your guess and my guess seem to be the same then.

  • PaintboxPaintbox Posts: 1,633

    Does an HDRI (exr) even have a colour space? I think the idea is that it encapsulates a full spectrum light environment of a scene.

  • M-CM-C Posts: 104
    edited February 2022

    I think the question originates from another thread in which we talked about the newly intruduced color profiles for spectral rendering.
    They´re a good thing in the first place but the problem is that none of them look like spectral rendering did before which makes it difficult to use now without adjusting every single texture of an asset that contains color data.

    Post edited by M-C on
  • cgidesigncgidesign Posts: 442
    edited February 2022

    Paintbox said:

    Does an HDRI (exr) even have a colour space ...?

    I learned, the answer is no and yes.

    No, it does not include a profile describing the color space.

    Yes, openexr (maybe hdr as well) either contains information about the RGB primaries and whitepoint which indirectly tells about the color space or - if the info is missing - the spec. says to assume the primaries of REC 709 / BT.709 (which are the same in sRGB). If one is in an ACES pipeline the RGB primaries and whitepoint are different (the new spectral in DS seems to take care of writing the RGB primaries information via the new user choice). Knowing this, I now understand that simply importing an exr into the image editior of choice does not work. We need to know which primaries are in the exr and how the developers implemented exr import in their software. I have to investigate further.

    The other question is the gamma curve. There it is more clear. EXR is linear. So, when final output is REC709 then gamma 2.4 is the one of choice, when  sRGB then 2.2 (not exactly but near to that).

    Does anybody know of a tool to read the RGB primaries and whitepoint from an exr file? I searched the net but no luck.

    EDIT:

    Ok, Fusion in Davinci Resolve can show the exr metadata.

    Now we know that DS 4.16. with spectral off is writing sRGB / REC.709 primaries and REC.709 gamma 2.4. So, DS is writing REC.709 metadata not sRGB as I initially thought.

    What I don't know yet is, what does Affinity Photo's color managment do with this information? Its default color space for 32 bit images is ProPhoto which has different RGBprimaries than sRGB or REC.709.

    RGBprimaries.png
    688 x 401 - 132K
    Post edited by cgidesign on
  • PaintboxPaintbox Posts: 1,633
    edited February 2022

    I have a few EXR applications, I will try and check if any of them work with what you described.

    Post edited by Paintbox on
  • cgidesigncgidesign Posts: 442

    You posted before i finished editing smiley

    But I am curious what your tools tell us.

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