So I use GIMP a fair amount, in windows. It's free and does the job I need it to do most of the time. It really doesn't have a good built in noise reduction plugin. I have used NDNoise with decent success, but it is a standalone **** program. I ran across this plugin for GIMP: Wavelet denoise | GIMP Plugin Registry The nice thing with it is it allows noise to be reduced in Y, Cr, and Cb channels independently. It also has a "detail" setting which really tells the algorithm what type of noise to reduce, high or low frequency noise, per channel. I took some Imaging Resource shots that were converted to JPEG from RAW for the E-P3 and ran them through the process and compared to the standard JPEG output. I was much suprised at how well the plugin works compared to the in-camera noise reduction algorithms.