Hi, are you unable to get hold of the Display P3 ICC profile?
I can send you it if you give me a pm with an email address
Overall this is a pretty bad situation and I'd like to try help:-
You wrote:"
Not all of them check the color management policies in color settings, so it may result in different color profiles when saved.
And I can't control them over this part. So I have to manually assign or convert color profile to Display P3 in Photoshop."
That’s risky. Maybe they just discarded the embedded ICC then it's OK to assign Display P3,
BUT (this CAN can happen for sure)
how about they opened your P3 image - converted it to their default working space [maybe sRGB if they don't understand color settings] then save, perhaps without an embedded icc.
Then it would be a very bad idea to assign Display P3. You COULD, of course, **convert to P3 BUT you'd need to be sure about the profile they converted to if its not embedded. PLUS converting between color spaces it potentially damaging.
**Let's say they have Photoshop set up [out the box] with the sRGB working colour space, and they take the option to "convert to workingspace". That move just potentially discarded a load of colour/detail.
Display P3 is a larger colour space in some areas than even AdobeRGB (1998) - it's WAY larger than sRGB in some areas. So the colour is gone, including the risk of the removal of detail in high gamut areas. [clipping]
Just saying.
"The problem is there may be multiple people editing this image. Not all of them check the color management policies in color settings, so it may result in different color profiles when saved."
WOAH that’s a potential s**t show right there.
Passing on files to be worked on to someone who is unwilling to understand the implications of colour management settings and, thus, may be inadvertently converting to another colour space, or even assigning without thinking - can be damn risky.
I suggest making up some instructions for these people working on your files, it's time they joined the present rather than ignoring colour management.
I hope this helps
neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management