I recently got a PS SX130IS as a birthday present and of course jumped at the chance of installing CHDK on the memory card.
I'm very interested in using the raw image mode because its potential benefits compared to JPEG. I've fooled around a while in UFRaw interface, taken some shots in RAW and basically I'm trying to get the colour space to match the one in JPEG's produced by the camera, because they do have rather good colour quality, but I think I've hit a stonewall of sorts here.
I found pretty good settings otherwise - I'm using VNG four colour interpolation, denoise as required depending on ISO levels used for the shot, and manual WB by selecting a neutral grey/white (but not full bright) area from the image, which seems to be yielding good results. As colour profiles go, I've experimented with both standard sRGB and AdobeRGB1998 as output/display profiles, and because I don't have either colour matrix or ICC profile for the camera (don't think one exists yet anyway) I've been using "No Profile" option for the input colour profile.
So, what I'm doing is basically opening the JPEG on background, then tinker with exposure, gamma, saturation and white balance (by selecting different areas) to either match the colours in JPEG as closely as possibly, or otherwise get satisfactory results.
However, this approach seems to be somewhat limited by UFRaw's interface, since I can only adjust saturation value globally instead of for specific colours. This results in following issue:
(here's the camera's original JPEG output)Like captioned text in image says - the global saturation value boosts the bluish shaded road as well as the green.
If I use Saturation 1.0 value, then the green is bland and unsaturated. My empirical comparisions using Eyeball Mk.1 calibration sensor system tells me that when saturation is set to 3.0, greens (vegetation) appear similar to how they look in JPEG, but rest of the image looks oversaturated, while if I set saturation to 1.0, most of the image looks fine except the greens.
Now, this is not
necessarily a problem as such. Some would say the colours in the manually adjusted RAW file look more vivid; your mileage may vary. However, I would prefer it if I were able to match the colours with the JPEG as closely as possible in UFRaw (or other RAW handling program; UFRaw is just convenient because of its interfacing with GIMP). Of course I can manually adjust the saturation of different colours in GIMP after the initial RAW handling, but I'd much prefer to do it with UFRaw because GIMP as such only supports 8 bits per channel colour depth, and that results in cumulative quality loss per each colour operation, as you all probably know.
So... is there a RAW handling program that includes separate saturation values for different colours, or do I have to do this in GIMP after outputting the image from UFRaw?
EDIT:
Overall, though, I'm fairly happy with the quality gains using raw images. Here are a few sample details of the JPEG and raw results of same photo:
Ignoring the slight blurriness on the RAW shots (that's just a matter of finding good unsharp mask parametres), the image quality is noticeably better than on JPEGs. At least in my opinion. Still not sure how to deal with the colour space.
