Post noise reduction - jpeg or raw?

Hello

Reading around the Raw posts I have decided to give it a go.

I don't like buying software, plus my computer is not powerful enough to take some of the new stuff so using GIMP. UFRAW has a denoise option but its pretty minimal, there are more options once in GIMP. Is there an issue with intially doing the exposure and WB in UFRAW then passing to gimp for Noise control & sharpening?

I am also wondering when the image is passed across to GIMP (still in RAW) does gimp reduce it to 8bit? If this is the case would it be better to convert to jpeg and then open in GIMP and carry out the noise reduction?

Many Thanks
Greg

There shouldn't be an issue with that, but it is obviously slightly better to reduce noise in RAW, before the file is reduced to 8 bit. You could try a different RAW converter like RawTherapee or (if you're on Linux) DarkTable.

When I edit mine in CS5 it opens from RAW as a 16bit file, now I can;t remember if I set this myself or CS5 does it automatically. I then edit and convert myself to 8bits before saving.

When i open Raw in elements 8 it is in 8bit, you can change it to 16bit on the bottom of the screen in a drop down menu.
What difference this makes if any i do not know.
Regards
Dave

I was under the impression that 12/16bits is what Raw is about, hence there is no compression of the image from the sensor so a little more to play with.

Rawtherapee just kept crashing on me, so not sure whether lightroom would work any better. Maybe its time to upgrade to a decent graphics card!

The original RAW file is 12-bits, or 14-bits (for the K5 etc). But in that form it's not much help - it needs to be demosaiced, white balanced, curve adjusted, and other various RAW conversion processes.

When you convert from RAW you have the option of converting into an 8-bit or 16-bit image - where each pixel is represented by 8-bit-Red, 8-bit-Green, 8-bit-Blue or 16-bit-Red, 16-bit-Green, 16-bit-Blue.

If possible, it's always best to do noise reduction in the RAW conversion process (as with Silkypix or Lightroom) since the software is doing the conversion from the original RAW. Once you've turned it into TIFF or JPG the noise parameters will be different (because the values have been 'cooked' by the process of going from RAW).

Also - you should use 16-bit output when you want to do heavy adjustments to an image once converted from RAW. It will help prevent posterisation when really shoving the values around. If you intend to convert into the ProPhoto colour space you should likewise use 16-bit output.

Generally, though, a good quality converter from RAW into 8-bit AdobeRGB or sRGB will be perfectly fine (and save you a LOT of space on the HDD)!

Hope that helps!
Matt