Monday, July 16, 2012

First Look--RAWTherapee's New Noise Reduction

Last Wednesday during this hottest on record Midwest heat wave Charlotte and her Mom and I drove in air conditioned comfort  to tour Charlotte's favorite museum, the Milwaukee Public. There Charlotte became my guide. My Nikon D7000 hanging around my neck, she led me from exhibit to exhibit.

Excellent exhibits, I'll admit. But from a low light, hand held photographer's point of view, the trip was not a successs. The lighting, or lack of it, was the pits. Still, I snapped away and came home with a few GB's of images, hoping for some lucky shots.

What I discovered when I went to process the RAWs wasn't luck exactly. I've been following the development of RT's new noise reduction routines for over a year and I check their forum regularly. The developer's denoise compile I downloaded isn't bug free and only works with 64bit Win7, but with my new computer its match with my museum snaps was perfect.

This snap was taken at a 1/4 sec and ISO2500.  Charlotte held her pose. Image stabilization and I held the camera steady. After a 2 EV boast in exposure and a tone curve, it's a decent image to see how well RT's latest and greatest works. There is no manual entry yet but the routine turned out to be more automated than I expected and easy to work out.

The luminance slider sets the maximum strength of the noise reduction; the luminance detail slider sets how much of that maximum strength is actually used. At a detail setting of 100, no or very little noise reduction is applied. At 5 and with a strength of 20--the settings I used here--the noise reduction was both artifact free and very impressive. But I was clearly losing detail as you can see in comparison with an image with no noise reduction (right)  below

I'd gone too far. Below is a tuned version where I tried to preserve detail.

I kept the luminance setting at 20 but ran the detail slider up 60, added more unsharp mask sharpening and set the gamma to 1.4 to bias the noise reduction towards the shadows. Below is another comparison with the no noise reduction image. Beside being significantly less noisy the tuned image shows as much and perhaps even more detail than the no noise reduction image. Click on the image and go to the original size if you want a better view.

 (note--if you download this build from RL convolution sharpening is broken, When you process an image in the queue the software grabs all the available memory and crashes when it can not find more.)

To finish off this first look here are the respective noise profiles--05 detail on the top, tuned detail in the middle and no noise reduction on the bottom.

While this is not the released version and there are still some bugs to work out, I'm  very impressed. So congratulations to everyone involved.