another color management question

[s_gru]

hello all, another color management question.

if i save out JPG or TIFF files from Vray frame buffer or IPR, i'm able to open those files in photoshop > get warned about no embedded color profile > i assign my custom monitor profile > then select "and convert to working space" (my working space is sRGB).

this way, the image in photoshop now looks almost exactly like the frame buffer or IPR (which i believe are one in the same but referencing both here in case it makes a difference).
i believe this happens because my vray bitmaps and my color management settings (in rendersetup) are set to "Rendering RGB primaries" - sRGB. (i do not currently name my bitmaps with _sRGB or _lin_RGB and all that).

sRGB: what i'm finding is, the amount of adjustments (levels, curves, colors) are limited because of the smaller gamut of colors and bit depth. some adjustments can create a lot of banding for example, in the sky/clouds.

aRGB or ACEScg? these two color profiles have a wider gamut! i'd like to be able to use one of these as i can get more colors and therefor eliminate or minimize banding in a sky for example. EDIT: assuming 16bit file

HOWEVER i need the colors in photoshop to match what i see in the frame buffer/IPR. i will work with designers and they often have me tweak bitmaps or colors to match what they want (rather than a real physical material) and i use the frame buffer/IPR to tweak until they like what they see on my screen (fb/ipr)

so i _think_ what i'm looking for here is the frame buffer/IPR to take raw data from the Vray render and display it in the widest possible color gamut, then save the file out (i usually use 16bit tif files - but this could change if need be). but, somehow convert the preview to look like a specific color profile. almost like soft-proofing within photoshop.

how can i achieve this?

TMI: at some point i'd like to do .exr files but i'm seeing some weird things, for example photoshop is giving me a message that the.exr file type does not support profiles so i'm stuck assigning a profile (for example my custom monitor profile) then converting to sRGB (to match frame buffer/IPR) as if i choose aRGB the two obviously don't match. PS does not let me choose the option "do not color manage this document" as it's greyed out. but i can turn that off and i get a xxx98 linear color as a profile? it wouldn't match anyway i think.

thanks!

[piotrus3333]

first thing to do if you are using custom monitor profile is to load it into VFB so you can see it correctly.
limited adjustments are caused by insufficient bit depth.
aces is not what you need for now.

[s_gru]

when aces or srgb is set within 3ds max render setup > settings tab > color management roll-out, when i save the image that is in the vfb via the save current channel menu 16bit tif file, what color numbers am i saving here? the color numbers from the monitor profile or the aces color numbers from the render setup window?

R151 G84 B22 in one color profile is not the same as it is in a different color profile.

ps - i've edited above in the argb/aces to note 16bit data.

[piotrus3333]

depending on the settings you are saving linear srgb or acescg. and for both you need at least 16 bit half float exr to save all the raw output from vray.

also VFB in VRay does not allow for icc profile and ocio at once so sort the srgb first. load your monitors icc into frame buffer and it should match 1:1 photoshop.

[s_gru]

"save RGB primaries conversion to image" appears to not do anything when saving the image? otherwise attached are my screen shots.

loading in photoshop or some other app is not addressed in here: https://docs.chaos.com/display/VMAX/...Workflow+Setup however maybe thats what OCIO is for - actually saving then numbers of a certain profile into the image?

the closest i seem to come no matter if it's JPG or EXR or 16bit TIF is opening the image in photoshop and assigning my monitors profile much like what's in the VFB. it's still reported as a high bit depth image which means i should be able to get a fair amount of tweakability, but a small color gamut is a small color gamut. you can't get extended greens or reds etc.. EDIT: the smaller gamut will give more "steps" between very-light-green and maximum saturated green, but that maximum saturated green isn't as far away as with a wider gamut.

[s_gru]

forgot to attach .exr file save dialog

[piotrus3333]

do you have a wide gamut display?

edit: also icc in vfb is just for preview, does not save. all good there, asign it in ps. but stay in srgb within vray.

[s_gru]

i don't have a wide gamut display. yeah i think that's just about the way of it then. it's really funny though, and maybe it's something in photoshop, i can do a dramatic curve in the vfb and not get any banding like a similar curve in photoshop. so i was thinking somethings going on in vfb that better represents the bit depth or gamut. i'll screen shot those and post.

[s_gru]

ok here's a screen shot. on the RIGHT is the vfb with very strong s-curve. then i saved the image as a 16bit tiff, opened in PS and applied my monitor profile when PS asked what i wanted to do. the s-curve that was applied in vfb was retained.

it's an old profile and i'll update it soon but it's the same in theory affecting the display of vfb and in photoshop.

[s_gru]

also, at this point ignore the obvious tone difference in the blue sky

[piotrus3333]

both images show banding.
set vray to srgb and not acescg. you are mixing too many things now.
you need to match all the transforms you see between vfb and photoshop. by default ps should apply lin srgb to srgb conversion to 32bit float exr. set this also in vfb: Display correction: sRGB.

banding is bit depth issue first.

is that a factory profile or you made it yourself?
LCD monitor test images (lagom.nl) use this to check if colours are ok. you can use it to manually calibrate so you do not need the icc profile. makes it easier in VFB - you calibrate to srgb and and set windows and photoshop to srgb.

[s_gru]

custom profile with colormunki photo and argyll

that site is more for checking profiling and calibration rather than setting it. i'd be wary of using that to manually calibrating.

so. if i render, set the monitor profile in the vfb with srgb in render settings, un-check "save RGB primaries conversion to image" save at a 16bit tif file. when i open in photoshop and "leave as is, do not color manage this document" my colors (reds, blues greens) seem to be off a tiny bit, but my contrast or gamma - my darks are washed out compared to vfb.

if i do the same thing but this time in photoshop assign my monitor profile, the contrast or gamma curve (whatever it is) is better, my darks match the vfb, but the colors are off more.

oh - and all of this happens when vfb is set to srgb as well - it's never a match.

it's like pick your poison. the gamma curves can affect the colors (if that's what's happening?) so who knows.

i'm not even going to look at 32bit files at this point.

thanks for you help but i don't think there is ever going to be a match because we don't know how the vfb handles colors and there's apparently no way to standardize it even when selecting display correction settings.

maybe vray is looking at a different srgb profile that choas incld in the install. or maybe photoshop is looking at a different srgb profile? the closest "standard" should be pointing both vfb and photoshop to my monitor profile no?

[piotrus3333]

if vfb is set to srgb that mean icc is not active. you need icc loaded into vfb.
what gamma are you saving the 16bit tiff with?
can you share the icc?

[s_gru]

yeah i thought i showed that in screen shot above - the icc loaded into vfb. not sure what gamma the 16bit tiff is saving with because it doesn't look like there's an option for choosing gamma unless i'm missing something. - oh you mean in the save dialog... intersting i was using automatic, but i will try different gammas now... attached is the icc file. hey, another thing, this icc file started out life as an icm file. i just made a copy and renamed it - as far as i read, that should be OK?

EDIT: nah, saving with different gamma settings other than automatic, then adjusting for them in photoshop doesn't make a difference.

[piotrus3333]

ok. seems to work ok on my side.
I used different icc just to be safe (icm vs icc - no clue, haven't been using icc for ages).
the correct icc is setup in ps color management and vray. you mentioned doing some conversions, possible that you lost some accuracy there. I just assigned srgb during file opening in ps.

there is measurable difference between swatches of 0.004 RGB on one or two channels in some places but nothing noticeable.