custom camera profile, Assign or Convert?

[paulbk]

re: custom camera profile made by ColorEyes™ 20/20

How should I use a custom camera profile in Photoshop CS2. Some say “Assign” the profile to the image file which will only apply the profile but not change the numbers in the file.

Why not use “Convert” ...which will change the numbers in the file? Isn’t that what I want to do?

p

[Tim Gray]

re: custom camera profile made by ColorEyes™ 20/20

How should I use a custom camera profile in Photoshop CS2. Some say “Assign” the profile to the image file which will only apply the profile but not change the numbers in the file.

Why not use “Convert” ...which will change the numbers in the file? Isn’t that what I want to do?

p
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the convert process, as you note, alters the file - so to mimimize permanent (irreversible) changes you should just assign, except...

for posting to the web.  Today's browsers have no way of reading the embedded/assigned profile so to get SRBG properly displaying on a browser you need to convert to that space.

[paulbk]

Tim,
Thanks for the get back. But I’m still not sure of the work flow.

1) Let’s say I convert my RAW file in ACR to 16 bit TIF and Adobe98 color space.
2) Also assume my CS2 working space is Adobe98. Therefore, there is no change when I bring the image file into Photoshop for edit since the working space is the same as the image tag.
3) Now.... is this where I should “Assign” the custom camera profile made in ColorEyes 20/20?

And is it true that whether I Assign or Convert to the camera profile, as long as I “Convert” to sRGB for web use, I should still get the benefit of the custom camera profile?

[Tim Gray]

Color Space (eg sRGB) is not the same as a device (eg camera) profile.  Your camera profile will simply adjust the hue and saturation for each color to better match an objective standard - such as a Gretag McBeth color chart.  A color space defines what colors can _potentially_ be portrayed - ie what the Gamut is.

The workflow should be:

open the image in ACR
click on the Calibrate Tab
choose the camera profile you want from the Camera Profile drop down (if it doesn't show up maybe someone else can help you get it installed in the right location)
 
You should see the hue and saturation setting for each color change based on the profile.

Proceed with the RAW conversion as you would normally, noting that the color space is choosen in the bottom left of the screen (raw has no intrinsic color space), so I guess in some sense the RAW file is "converted" to the chosen color space as part of the RAW conversion.  The best space into which to convert the files is subject to debate - search this forum for ProPhoto RGB for the relevant discussions.

[pfigen]

ACR does not allow the use of a custom camera profile. ACR uses two camera profiles internally, one for daylight and one for tungsten, and allows you to interpolate between the two using the color temperature slider. If you use the calibrate function in ACR and save the settings, that can, in effect become your new default profile, but it is not the same as making a custom camera profile and using that. In order to do that, you'll need to use something other than ACR for your raw processing. C1  comes to mind.