corona vfb v image in photoshop

[tom182]

apologies as I know this has cropped up before but I just cant seem to get this fixed,
attached image is difference in Coroana's FB and the image opened in PS (when Ps is set to SRGB profile)
I was probably incorrectly using Monitor RBG in PS as the proof setup so switching that to Internet Std srgb causes a massive difference in Corona FB and PS

reading Juraj's replies here https://forum.corona-renderer.com/index.php?topic=13592.0
am i right in saying that framebuffer is wrong as it is oversaturated due to FB is non-colormanaged

What i have tried as a fix
save image from corona VB as a CXR, OPEN cxr in Corona image editor and save out as PNG,
Have photoshop's colour settings set to  monitors i.e. the Dell U2713
So when i open image (saved out of Corona'S FB as an ) in PS i will get a noticeable difference, To get the image looking similar in Photoshop I set the if i save that out for say a web image (convert to srgb is ticked)

appreciate any info,


max 2018 , gamma set to 2.2
monitor Dell U2713H - set to auto,

[James Vella]

have you tried saving your image as 16 bit half float exr and loading that into photoshop? does it look the same as the vfb?

are you photoshop settings set to default - or have you changed the color settings management policies?

are you working in a different color space in photoshop? if you are - are you selecting 'assign profile' or 'convert to profile' (if neither ignore this last question for now).

[Juraj]

It doesn't matter what you save from 3dsMax (8/16/32bit, any file format), because the software isn't color managed as a whole and neither is the image exporting process (regardless of renderer).

Unless you "clamp" your color-space of monitor to low-gamut sRGB by 3DLUT in monitor's OSD (Hardware calibration), what you will see in 3dsMax will always be incorrect (oversaturated because it spreads to the whole gamut).

Photoshop by default is color managed so what you see is correct, unless you attach incorrect color-profile (monitor one or general wide-gamut).

Here are two only current possible solutions if your monitor doesn't feature hardware color management and you like to keep wide-gamut:

1) CORRECT colors: You import your file in PS and simply live with the fact you can do final color evaluation in post-production. The saturation in 3dsMax will be wrong and you have to think about it.
2) WRONG colors, but identical image transfer: If you want the SAME (WRONG) colors like you see in 3dsMax on wide-gamut monitor, you have to attach the same color-profile your monitor is using. This will give you wrong colors (you aren't converting between color-spaces but simply transfering the same values). You can then convert to sRGB when sending it to clients or uploading to website.

I know plenty of people who do the second :- ). If you don't need exact colors (for furniture clients), then you will simply live with the fact you are absolutely bypassing color management.

[James Vella]

It doesn't matter what you save from 3dsMax (8/16/32bit, any file format), because the software isn't color managed as a whole and neither is the image exporting process (regardless of renderer).

Well there is a difference between exr and png, png is slightly more desaturated - but just a little bit.

2) WRONG colors, but identical image transfer: If you want the SAME (WRONG) colors like you see in 3dsMax on wide-gamut monitor, you have to attach the same color-profile your monitor is using. This will give you wrong colors (you aren't converting between color-spaces but simply transfering the same values). You can then convert to sRGB when sending it to clients or uploading to website.

+1 this method. It seems to be what is wanted in this situation right, to match the vfb? You can then adjust what you need in photoshop further if you need to, otherwise you can just adjust it if you prefer using the VFB.

[Juraj]

It doesn't matter what you save from 3dsMax (8/16/32bit, any file format), because the software isn't color managed as a whole and neither is the image exporting process (regardless of renderer).

Well there is a difference between exr and png, png is slightly more desaturated - but just a little bit.

This is not due to color management, but there indeed are some discrepancies due to incorrect implementation of some file formats in 3dsMax ( esp. png and tiff). This is still done by 3dsMax even if you save from Corona framebuffer.
There are many such small issues (like black levels of 16bit Tiffs) or downright catastrophic issues (B&W 16/32bit Tiff support).

These issues are there regardless of monitor color gamut and are for most part much more minor than color gamut different between sRGB and whatever else wide gamut (aRGB, DCI P3,etc...).

+1 this method. It seems to be what is wanted in this situation right, to match the vfb? You can then adjust what you need in photoshop further if you need to, otherwise you can just adjust it if you prefer using the VFB.

Yup, I believe most people prefer this method, as there is nothing wrong or restrictive in it in artistic way. The only issue I can see even if you don't need precise colors, is that you can't just desaturate the image and get "correct" colors, because the difference between your monitor gamut and sRGB can be completely arbitrary, the reds will be more affected than greens.

But ultimately, what you don't know, doesn't hurt you :- ) I am color bling for red/green spectrum, and I didn't know it for 25 years !! Until one day I haggled with my now wife Veronika about what color is particular forest reference :- D. I swore it was "reddish", we took tests, she ended up in 99.6 percentile and I 40 lol. But I just look at forest references, make it look the same, doesn't mater that I see something different than anyone else :- ).

The issue is really only for product design, but that has so many other issues than just color management (the HL compression is terrible too...)...

[tom182]

It doesn't matter what you save from 3dsMax (8/16/32bit, any file format), because the software isn't color managed as a whole and neither is the image exporting process (regardless of renderer).

Unless you "clamp" your color-space of monitor to low-gamut sRGB by 3DLUT in monitor's OSD (Hardware calibration), what you will see in 3dsMax will always be incorrect (oversaturated because it spreads to the whole gamut).

dell u2713H OSD gives 4 options , Adobe RGB, sRGB, CAL1, CAL2, sRGB is checked, how can i do that ? is it via the OSD?

Photoshop by default is color managed so what you see is correct, unless you attach incorrect color-profile (monitor one or general wide-gamut).

So should i set PS Colour settings to dell's monitor specific profile,  srgb or AbobeSRGB

Here are two only current possible solutions if your monitor doesn't feature hardware color management and you like to keep wide-gamut:

1) CORRECT colors: You import your file in PS and simply live with the fact you can do final color evaluation in post-production. The saturation in 3dsMax will be wrong and you have to think about it.
2) WRONG colors, but identical image transfer: If you want the SAME (WRONG) colors like you see in 3dsMax on wide-gamut monitor, you have to attach the same color-profile your monitor is using. This will give you wrong colors (you aren't converting between color-spaces but simply transfering the same values). You can then convert to sRGB when sending it to clients or uploading to website.

if i opt for second option here, does this mean i set Photoshops Colour setting>working spaces  to "Dell's u2713H profile" ?

sorry for dragging this on but its a complete head wreck

[Juraj]

Your monitor does have hardware calibration :- ). The CAL1 and CAL2 are OSD stored LUTs. This is superior compared to software calibration (in Windows color management settings), but it just bypasses what OS is doing and cut offs colors outside of calibrated color space.
If your monitor is fairly new (less than 2 years), you can just select the sRGB. If you want more precise calibration, you need x-Rite i1pro spectrometer (this is because Dell tied their color software from x-Rite to this particular series, don't just use any other, like Kolormunki,etc..). This will let you do custom calibration and let you choose a color space as well (so you can have sRGB CAL1 and aRGB CAL2 for example).

It's possible to also do both hardware calibration and software calibration at same time for absolute ultra-precision. This is done by first profiling the custom CAL profile to get as close to intended color-space, and then afterwards creating system profile for Windows that will use the CAL profile.
But this will once again only work with color managed applications, so I suggest only to use hardware calibration (either default sRGB, or custom CAL1 sRGB later), and using generic color profile in Windows (use sRGB IEC61966-2.1, not default "display profile"). This negates any color management in system, but at this point we don't need it much because the monitor is doing it.

You can then set Photoshop to either ignore color profiles (it will do the calculations in generic wider gamut but it will still show sRGB on your monitor because the monitor is doing soft-proof automatically with the clamped sRGB profile.
You can then convert to sRGB when you save the file.
Or you can just assign sRGB at beginning (the 3dsMax saved files don't have profile, but they also don't have range above sRGB either, so this won't make any incorrect change).

This way, both unmanaged apps (3dsMax, WindowsPhoto,etc..) and managed (PS,etc..) will look the same and both will be correct (sRGB).

It's quite sad that you lose the wide gamut of expensive monitor, but such is life when Autodesk is behind the times. But majority of people don't even have sRGB monitors at home, and most cellphones on Android are not color managed either so...there you have it :- ).

[tom182]

much appreciated Juraj, i think i am actually getting somewhere now.

So I have used the OSD To set it to CAL1, monitor is about 5 yrs old :-( these were well priced monitors  for what they offered.

it just bypasses what OS is doing and cut offs colors outside of calibrated color space.

There is also a Dell Display Manager that allows profiles and screen layout to be set, I have set that to CAL1 also (this was set to auto, which would probably explain that when i ran windows media player the screen would get darker as it was an unmanaged app) image attached,
setting this to CAL1 in manual mode seems to apply this LUT to everything e.g. browsers etc. which is ok - it just looks a tad yellow,
If that is all i need to do with the monitor,  in Photoshop should i set to use the sRGB profile or the dell's profile as shown in image?

You can then set Photoshop to either ignore color profiles

   i.e. set 'Colour Management profiles> RGB to 'Off' ?
cheers

[James Vella]

Correct me if Im wrong but you wont need the last step (windows color management device profile) as Photoshop is using CAL1 already to display the wider gamut as per juraj comment below.

But this will once again only work with color managed applications, so I suggest only to use hardware calibration (either default sRGB, or custom CAL1 sRGB later), and using generic color profile in Windows (use sRGB IEC61966-2.1, not default "display profile").

In 3dsmax you are seeing the VFB with CAL1, but thats not what the render actually looks like (but it doesnt matter we opted for option 2 in juraj scenario).

So now in photoshop we create a new file and select 'dont color manage' as juraj mentioned.

You can then set Photoshop to either ignore color profiles (it will do the calculations in generic wider gamut but it will still show sRGB on your monitor because the monitor is doing soft-proof automatically with the clamped sRGB profile

Import your render, it will look the same as the VFB. Adjustments from here on will use your monitor gamut so you can adjust colors as needed. So if you want to ensure it looks like it does in Photoshop in the JPG you must Export As - Convert to sRGB.



(A good idea to select 'embed color profile' as well to make sure other software knows its an sRGB profile).

In Photoshop > Proof Colors - Internet RGB should appear the same as well.

**edited for clarity

[Juraj]

Yeah, just like James writes.

Just small note: You can use CAL1 only if you profiled that CAL1 :- ). CAL1 and CAL2 are just custom empty slots, no idea what they are from factory, probably something pretty vivid.

[tom182]

thanks Guys,
still not sure if i have set it up correctly (I have acquired a mental block on this topic :-(
but what i have done and i seem to be getting betting looking images or should i say closer looking images to what the Corona VBF shows when i view them in win's 7 Photo Viewer
1) set OSD to cal1
2) in PS set colour profile to Dell's monitor
3) open a png that was saved from the corona VFB image in photoshop with the option to 'leave as is  Don't colour manage'
4) export it out with 'convert to sRGB' checked,

result is that this new image is close to my original post  comparison image - the one on the left side i.e. vfb

[James Vella]

2) in PS set colour profile to Dell's monitor

Just be careful doing this as when making your textures in photoshop you will want your color space to be in RGB as this is what 3dsmax will expect.

[sprayer]

Also note what all chromium base browser have bug what by default may take wrong color profile from system and all images may looks different or dull