UFRaw
UFRaw is a very versatile tool for RAW processing. It can be used both with Gimp and with Photoshop. I tend to use Gimp, mainly because Gimp is free and available. I can not justify buying an expensive product when a free tool does very good job. I feel that some Gimp scripts are very good and that compensates for rough edges of Gimp GUI. UFRaw can be used as a standalone tool and as a Gimp plugin. As a standalone tool it would produce 8 or 16 bit image files. These files can be used for further processing in Photoshop. There are reasons why you would want to go this route even if you have great tools like Adobe Camera Raw plugin. Main processing steps for Gimp and Photoshop are the same. Please read to the end of the article for detail explanation of each step.
- Load raw image
- Apply camera curve (called "Base" in UFRaw)
- Adjust white balance, gamma and exposure
- Apply Luminosity Curve (called "Correction" in UFRaw)
- Adjust Exposure level
Camera Curve
I use free tool HDRShop for camera calibration. Version 2 is commercial, but version 1 is available for non-commercial use. Fortunately free version has an option to "Create->Calibrate Camera Curve". Download HDRShop and use this tutorial to create your camera curve. But, oh boy, the curve created in HDRShop is in Matlab format! How do I use it in UFRaw? There is no simple answer for that. I am planning to write a tool for that in the future, but for now I do it manually. Please register to this web site and send me your HDRShop curve. I will transform it to UFRaw format if time permits. Please include camera model in your message as well. Try to use custom curve that I have created for my RebelXT I would like too know how this curve works for you.
| This is test image without custom curve (linear curve is used) | This is test image with my Canon RebelXT custom curve |
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| Test image with no corrections. All values at default. Base and correction curves are linear. Gamma=1, Gamma linearity =0 and exposure =0 | Custom Canon RebelXTcurve is applied to Base |
Adjust White Balance, Gamma and Exposure
Next is to set white balance to match color temperature at shooting time. It is best if you went through trouble of using 18% Gray Card to set custom white balance. Second best is to use one of the presets, and last resort is set it to Auto. If you are able to set color temperature by eye, you probably do not need this article all together :-). I set AdobeRGB1998 as input profile because this is my camera setting. If you used sRGB on the camera, you should set input profile to sRGB. I want to point out that I use ProPhoto as output profile. ProPhoto is a profile with widest gamut. If you use UFRaw to create image for use in Photoshop, then this is probably the best choice. You can download ProPhoto profile from Dodgecolor profile download page, or, if you use Photoshop, you can find it in Photoshop installation directory. If you are going to use Gimp, then it is better to use UFRaw as a plugin. In this case image will be loaded into Gimp converted Gimp working profile. Whole profile and gamut issue deserves careful attention in a separate article. Here is image after adjustments 
Apply Luminosity Curve
I found that Nikon custom curves work very well here. I use Fotogenic curves for that. Here is image with Photogenic White Wedding V35 is applied to as Luminocity curve. 
Final Touches
Sometimes at this point you would want to go to Color tab and adjust gamma and linearity. You might want to play with exposure and Luminosity curve. For curve adjustment, do not use mouse. Use keyboard arrows and PgUp and PgDown buttons.