CHROMiX

Correct Use of a Camera Profile

What’s the best way to use a camera profile for copying fine art using a digital camera? Or, for using a camera profile in general?

In creating camera profiles in PM5, I photogrphed the standard SG target that comes with the PM5 Camera profile module, I get an error message that indicates my grays are off, and that I should gray balance the target.

I draw a couple of conclusions from this error message:

One, that camera profiles aren’t used like scanner profiles. (i.e., camera profiling software works differently.)

Two, that if I need to gray balance at the time of exposing the target, I probably need to gray balance at the time that I take a photo of a scene. (If so, then I’m thinking that, after creating a camera profile, I have some leeway on the lighting set up in subsequent uses of the profile, as long as I stay with about the same color temp of the light.)

So, in photographing fine art, I’ve been using the following procedure:

  1. Photograph fine art and target, one after the other in the same lighting.

  2. Prepare target for PM5 Camera Profiler in CS3 Photoshop by getting rid of dust and doing a gray balance. I do white pt balance, black pt, and then gray balance in levels. After this, I save the levels gray balnce adjustments.

  3. Build the profile in PM5.

  4. Open the image of fine art in PS and apply the gray balance adjustments that I saved after gray balancing the target. Then assign the camera profile.

  5. Continue with croppiing and other PS non-color adjustments. Save image.

Is this correct? By the way, I still get the gray balance error!

Is there a downside to treating the camera like a scanner and using a scanner profile for reproducing fine art?

Also, I read the following out of Real World Color Management: “If you use Adobe Camera Raw as your preferred raw converter, you’ve likely already relaized that you can’t use custom camera profiles, because the profiles are hardwired into the Camera Raw plug-in.” Chpt 9, pg249) In fact, I’ve been using ACR. Does Fraser’s et.al. comment apply, even though I do everything the same in photographing the target as I do in photographing the fine art?

I’ve read everything I can about the proper use of camera profiles, but info is scarce. Any input will be appreciated.

By the way, I’ve been using CS2, not CS3. Also, after following my procedure, the image sort of turns a faded color that doesn’t look like the original art, and it seems like I still need to do some levels work to make the image look right.

I can’t answer all of your questions, but the folks at Integrated Color Corp have done a lot of research on camera profiling. The key thing they found was to pay very close attention to how you capture the target. There’s a 3 or 4 page description of what they found on their website:

http://www.integrated-color.com/cecamera/overview.html

Hope that helps,