ProPhoto RGB

[Jarrell]

I've done a little reading on this color space and would like to know if all I need to do is assign it in Photoshop?
I use a D100 and I normally shoot in Adobe RGB, Raw and I open them with Nikon Capture 4, maybe adjust white balance and exposure, save them as a tiff and then open in PS. Is it then that I change the colorspace to ProPhoto or do I need to do something in an earlier step?
Jarrell

 

[Doug Barber]

Greetings Old tmer....
I don't have an answer for your question other than to say I do it in PS the same as it seems you are doing.
Other than that I just posted to say Howdy.

 

[Gale]

JARRELL,

I have been doing it in PS.. But seems to me in NC it is there somewhere. Can't remember though.

Last time I looked for it in NC could not find it.

Works great with some images.. I find not all though.

 

[Gale]

PS: Iliah can give you the answer though.

Drop him a PM or maybe he will see this.
Thats who I learned of it from.

 

[Jarrell]

Thanks Doug and Gale. I've tried converting it within PS and as Gale said, there is a noticable effect at times and at other times there seems to be none at all.
Doug, I sure wish I was up there with you right now. The heat and humidity here are getting fierce as I'm sure Gale can tell you.
Jarrell

 

[JeffKohn]

You do not want to assign the profile, and honestly converting to the profile in Photoshop won't really do you any good. To take advantage of the larger color space you would want your RAW convertor to use it as the output color space. This is easily done in ACR where you have a drop-down giving you four choices for target color space. In NC, you would want to go to Tools|Options and on the Color Management tab use the browse button to select the ICC and then check the box to always use it (ie ignoring the tag in the NEF). Iliah has hinted in the past that due to the way NC handles conversions this may or may not be a good idea, maybe he'll chime in here. For people using ACR and editing in 16-bit, I think ProPhoto RGB is the way to go as long as your comfortable with color management, understand the differences between assigning and converting, how to soft-proof, etc.

 

[linm]

Jarrell;

I was playing around with it today and found a setting in Nikon Capture:Tools/Options/Color Management. It didn't seem to take ahold until I closed and re-opened the program. Then, it was in ProPhoto RGB when I opened it in Photoshop.

 

[Gale]

aaahaa I kew it was there somewhere... thanks for the reminder.

Of all the things i have lost , etc etc etc


thanks

 

[Jarrell]

Ok, thanks for the help. I do understand soft proofing and I usually do this when printing my own work. But, the difference between 'assigning' and 'converting' I'm not familiar with. I have a feeling converting is permanent whereas assigning is not?
Jarrell

 

[Philippe Roger]

Converting is recomputing the RGB numbers for the new color space (and storing those new numbers in the image file), so that the image visually looks the same, or as close as possible, as before. For instance, it is recommended to convert to sRGB when posting to the web, as most web browsers don't know how to interpret anything else (even if the profile is embedded in the image file).

Reassigning changes the interpretation of the RGB numbers inside the file, without altering the actual RGB values. As a result, this changes the colors on screen. This most useful when a file is known to be encoded in a certain space, but the file has not been properly tagged with the corresponding profile.

Clear as mud, huh? ;-)

 

[JeffKohn]

Philippe gave a good explanation of convert versus assign. I'll just add that convert is almost always what you want to do. Aside from the scenario Philippe mentioned (assigning the correct profile to an untagged file) I can't really think of any good reason to use assign.

Side note, many people are used to the fact that when switching color modes in-camera or in NC, the "look" of the image changes and they therefore think that Adobe RGB looks different than sRGB, for instance. In fact the change you see has to do with different color processing Nikon uses, not the target color space. In a properly color managed workflow, the only time you'd see a difference between using one color space versus another is if the image contains colors that exceed the gamut of one or more of the color spaces in question.

 

[Iliah]

"To take advantage of the larger color space you would want your RAW converter to use it as the output color space."

Hear, hear!

ACR uses ProPhoto internally, and it is better to keep the image in one colour space until converting for output (sRGB for web, or printer profile). Additional colour conversions introduce gamut problems, noise, and have other undesirable complications. It is really hard to trace the problems with colour spaces, as regular monitors can't display gamuts much wider then sRGB (one thing to use for checking for the problems is desaturation by 20-30% in Shift-Ctrl-K menu, Advanced mode checkbox "on"). Because of gamut limitations, there is no visual feedback on colour distortions, but only Info palette.

To present the opposite view: if one can't really read and interpret data from Info palette, and has little experience - he should use wide gamut colour spaces only if he can see definite problems on the image, like blown-out reds.

Yet, sometimes it is really helpful to trick NC into wider gamut space. To do so, one needs to press Ctrl-K, go to"Color management" tab, set the desired colour space under "Default RGB color space", and check the box "Use this instead of an embedded profile when opening files".

Re usefullness of assigning different colour space in cases other then recovering from missing/invalid tag - here is an example: https://www.nikoncafe.com//forums/viewtopic.php?t=7399

 

[Jarrell]

I appreciate the explanations guys, I have a much better understanding of it now.
Thanks,
Jarrell

 

[rblancojr]

While doing some research on ProPhoto RGB in the forums, i came across this thread. It led me to do some more research, and I am came cross the following link which I found extremely helpful.

i am sure that most of you have deceided to go ahead and work in ProPhoto, but this is what "sold" it for me.

http://luminous-landscape.com/tutorials/prophoto-rgb.shtml