DNG Profile Editor, ColorChecker and Lightroom

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DNG Profile Editor, ColorChecker and Lightroom

Postby ATJ on Thu Oct 23, 2008 10:10 pm

In my quest to get better colour results with Lightroom I have been looking at the colour profiles you can now use with Lightroom (well, ACR 4.4). There are some beta default ones for Nikon cameras but I wasn't all that happy with them - they seemed too dark (although I think I know why).

I recently purchased a ColorChecker (thanks Dave) and took a reference shot. I used my softbox to light it and chose the WB preset I recorded also using the softbox, so the white balance should be correct. I converted the raw file to DNG using DNG Converter. The DNG Profile Editor has a tab which knows about the ColorChecker, so I loaded the DNG file of the ColorChecker and let it rip. The colours "look" OK, but again, it is very dark.

After a Google search, I found this thread: http://www.adobeforums.com/webx/.3bc03c04.59b60785, where Eric Chan (the guy that wrote the editor) talks about how the Profile Editor (PE) only matches hue and saturation and not lightness. They want to leave tonality control to the user so it doesn't go into the profile (which explains why I have found them to be dark). I don't understand why they would do that (as the profile is only a starting point, anyway).

Now I'm stuck on how to set up tonality so that everything looks correct. I guess it means I have to play with the tone curve.

I did find this: http://lagemaat.blogspot.com/2007/09/lightroom-values-for-colorchecker-chart.html which gives what the ColorChecker's RGB values should be as displayed in Lightroom. I then just played with the Highlights, Lights and Darks settings on the tone curve until I got the values for the 6 grey squares on the ColorChecker to get close to the values in the above link. Am I on the right track? To be honest, I'm not sure I know what I'm doing.
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Re: DNG Profile Editor, ColorChecker and Lightroom

Postby DaveB on Thu Oct 23, 2008 11:12 pm

I'm in the middle of doing similar things for some Panasonic cameras. Can't talk to your specific issue but I'll look at it tomorrow.

You do know that for the best profile you'd take two shots of the ColorChecker (one under tungsten lighting, one under "6500K") and feed them both in?
It's outlined in Adobe's tutorial on the Profile Editor.
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Re: DNG Profile Editor, ColorChecker and Lightroom

Postby DaveB on Thu Oct 23, 2008 11:25 pm

Also, do you know that the profiles and profile editor at Adobe were just updated (October 22)?
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Re: DNG Profile Editor, ColorChecker and Lightroom

Postby ATJ on Fri Oct 24, 2008 3:27 am

DaveB wrote:You do know that for the best profile you'd take two shots of the ColorChecker (one under tungsten lighting, one under "6500K") and feed them both in?
It's outlined in Adobe's tutorial on the Profile Editor.

Yes, I had read that, but it didn't appear to be mandatory. It is something I can look at after I solve the tone issue.
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Re: DNG Profile Editor, ColorChecker and Lightroom

Postby ATJ on Fri Oct 24, 2008 3:55 am

DaveB wrote:Also, do you know that the profiles and profile editor at Adobe were just updated (October 22)?

I didn't, thanks for that, Dave.

I downloaded both. I don't see much difference in the profiles but the profile editor has noticeable changes both in how it works (it doesn't cope as well with a rotated image of the ColorChecker) and the end result (there is a slight change in the handling of "purplish blue" and "blue"). No change in the tone/"lightness", which is the problem I'm trying to solve.
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