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RAW and Camera Colour Profile
Posted: July 15th, 2011, 1:16 pm
by tomczak
Could someone offer a brief explanation as to what a Camera Colour Profile is, how to make it, how and when it is used in the RAW processing sequence and what happens when it is set to none?
Cheers!
Re: RAW and Camera Colour Profile
Posted: July 15th, 2011, 5:42 pm
by MarkT
Maciej, take a look at this earlier post:
http://www.dl-c.com/discus/messages/2/8454.html
I have used the Profile Mechanic software (from DL-C) with the Wolf Faust targets and reference files to create a custom camera profile (for a Nikon D2x among others). I've also downloaded trial versions of software like CaptureOne, etc, at which time you are provided with various camera profiles to keep and use.
There certainly are differences in the results with profiles from different sources, so some trial-and-error is to be expected to find the one that suits your tastes.
Hope this helps.
Mark
Re: RAW and Camera Colour Profile
Posted: July 16th, 2011, 6:04 am
by tomczak
Mark,
Thanks! I've tried the PhaseOne generic camera icc profiles (125Mb download to get 215Kb profile - are there any other sources of generic camera profiles?). They seem to work, but I'm not sure if I understand when exactly in the RAW processing they are applied. Two observations:
- when I tried it on Canon S95, there is a difference in some colour tints between using this camare ICC profile and using 'none', but the tints using 'none' in PWP RAW are closer to what the in-camera JPEG would produce then the tints when ICC profile is used. Is that expected?
- in addition to selective colour differences, using ICC camera profile also changed the tones: e.g. the processed image using the camera ICC profile caused less blocking of shadows than when 'none' was used, everything else being equal. How that can be explained?
Re: RAW and Camera Colour Profile
Posted: July 16th, 2011, 7:36 am
by den
Perhaps it is worth studying 'dcraw' so that conversion can be isolated from programed software edits... here are dcoffin's color options from his manpage:
COLOR OPTIONS
By default, dcraw uses a fixed white balance based on a color chart illuminated with a standard D65 lamp.
-w --Use the white balance specified by the camera. If this is not found, print a warning and use another method.
-a --Calculate the white balance by averaging the entire image.
-A left top width height --Calculate the white balance by averaging a rectangular area. First do dcraw -j -t 0 and select an area of neutral grey color.
-r mul0 mul1 mul2 mul3 --Specify your own raw white balance. These multipliers can be cut and pasted from the output of dcraw -v.
+M or -M --Use (or don't use) any color matrix from the camera metadata. The default is +M if -w is set, -M otherwise. This option only affects Olympus, Leaf, and Phase One cameras.
-o [0-5] --Select the output colorspace when the -p option is not used:
0 Raw color (unique to each camera)
1 sRGB D65 (default)
2 Adobe RGB (1998) D65
3 Wide Gamut RGB D65
4 Kodak ProPhoto RGB D65
5 XYZ
-p camera.icm [ -o output.icm ] --Use ICC profiles to define the camera's raw colorspace and the desired output colorspace (sRGB by default).
-p embed --Use the ICC profile embedded in the raw photo.
Re: RAW and Camera Colour Profile
Posted: July 18th, 2011, 7:11 am
by JvdW
As far as I understand it a camera profile describes the color gamut a specific camera can capture. This profile is allways somehow related to the lighting used while shooting a reference target. The general opinion on camera profiles seems to be that they are only usefull for studio shoots with constant lighting in combination with the need for really accurate colors.