Luminous Landscape Forum

Raw & Post Processing, Printing => Colour Management => Topic started by: thierryd on July 30, 2008, 06:44:33 am

Title: About The DNG Profile Editor
Post by: thierryd on July 30, 2008, 06:44:33 am
You wrote in the "A Digital Imaging Revolution in The Making"
It's worth noting that if you find yourself shooting under very weird lighting conditions, such as unknown fluorescents and mixed conditions, all that one needs to do is take out a ColorChecker (even the little pocket version) and take a shot of it under the unusual lighting.
Working with the color checker tab each time the light is a problem is quiet fascinating, but it doesn't work apparently. Under 4800 K, I have an error message: " Please reshoot the cast carefully to avoid color casts and try again."
And if I read the DNG editor tutorial:
Photograph the ColorChecker Chart under a 6500 K illuminant (e.g., D65 simulator), taking care to illuminant the chart evenly and to minimize color casts.

You have to take the photograph under a 6500 K illuminant.  
Title: About The DNG Profile Editor
Post by: madmanchan on July 30, 2008, 09:37:36 am
No, you can photograph the CC under any illuminant. The instructions you're referring to only applies to the case where you've specified that you want to use the Chart Wizard feature __only__ to build 6500 K corrections (i.e., you choose 6500 K from the popup menu in the Chart tab).

For your case, when you're building a profile for 4800 K, choose "Both Color Tables" from the profile menu popup and it will work fine.

Regarding the error: the DNG Profile Editor checks all gray patches to see if they are relatively free of color casts. This is a sanity check. There are 3 possible reasons you might be getting the error: (1) you really do have a color cast, in which case reshoot your target carefully or (2) your image is very noisy (should try using low ISO to shoot the CC), or (3) maybe you didn't position the 4 markers appropriately to identify the 4 color patches?
Title: About The DNG Profile Editor
Post by: thierryd on July 30, 2008, 10:46:44 am
Thanks Madmanchan for your reply.  
I worked with a D2x and 100 Iso.
I try different photographs, always with trouble, but at the end, I found a working  chart photograph. This photograph is a close up on the chart, and not the others, may be that's why I had some trouble ?
I will make some test tomorrow into my studio with different camera, different light with and without close-up.