Noise Reduction RT vs 'the others'

Two months or so back I had this post all planned out  The 'other' was to be my antiquated version of Adobe Camera RAW that came with Photoshop CS3. When I compared the noise on two of my images RT clearly lost with one image but tied with the second. Slightly confusing.

So I checked the RT forum  to see if there was some info I had missed. There I learnt that the noise reduction routines were being  rewritten.  I decided to wait for the revision. Then life interfered with blogging and I didn't come back to this until a few day ago.

mbod had already done the comparison where his 'other' was NeatImage.  The link for the discussion is http://www.rawtherapee.com/forum/viewtopic.php?f=1&t=3708  He provided this screenshot; I measured the noise in the sky with ImageJ

The interesting thing about these measurements is the noise profiles are nearly identical even though the RT processed image on the right looks much noisier. (click to view original size) That's caused by the relatively large chromatic blotches emil talk about in the forum post. They are what you see but since a line profile only measures noise that is a pixel wide, it makes the Signal /Noise look better than it really is.

Normally I do most of my photographic work on my 32 bit desktop machine. While I have 32 bit memory management problems, I also have a semi ancient Sun workstation monitor that was built to last.

And has lasted. With a large 1600 pixel screen, the monitor can be calibrated and color managed so the colors and values on the screen are identical to those I see on my prints. Just as important when I raise or lower my head, the image intensities don't change like they do on my laptop screen.

But this time I used the 64 machine after I downloaded mbod's RAW file. And I was surprised by what I saw after I ran it through RAW therapee.

The noise profile of the 64 bit jpg (left) was much less noisy than I expected. More important it didn't have the chromatic blotches that I have in my 32bit jpg (right) and that mbod had in his conversion.  (click the screen captures to view their original size). Big shock to discover there was that much difference between the two versions of RT.

     Both jpgs were converted using identical settings. The formula used was exposure compensation to correct for underexposure followed by RL sharpening with a radius of .50 and amount of .24. This was followed  by impulse noise reduction of 75 and luminous noise reduction of 49. All other settings were left at the default values.

glascort also posted a NeatImage conversion which I compared to my 64bit jpg.  While my noise is 4 times lower I lost fine detail like the guy wire on the tower (circled in red).  Larger detail like that on the side of the building (circled in blue) wasn't affected. But there is no question that my version is less crisp than the glacort's version.

That turned out to be rather easy to fix. I loaded the 64bit jpg into RT and upped the Lab mode contrast to around 30. That brought out more noise so I added a bit more impulse noise reduction. As you can see in my reworked jpg on the left, the noise is still lower than the NeatImage jpg, the overall image is as crisp and I recovered the lost guy wire (circled in red).

   While I don't have any of the 'others' installed on my 64 bit machine yet, I feel the current 4.0.6.3  64 bit noise reduction is quite good. So we might be far closer to overtaking ACR than some believe.

Sharpening--My Workflow

My next RAW Therapee tutorial was going to be a comparison of RT's vs ACR's noise reduction routines.  Unfortunate ACR was winning. Then I learned RT's noise reduction routines were having a major rewrite--see issue 1052 on the forum. So that tutorial is on hold while I wait for the new goodies to show up in an official build.

This tutorial on sharpening is short and I hope sweet.

I'm using a combination of RL Deconvolution and Microcontrast on most of my images. I can push things too hard and oversharpen but even then I don't create unsharp mask style halos. Compare the siding of the house in 200% box. Click on the screen captures and flip between the two images at the bottom of the screen for the best views.

With sharpening on and at or close to the default settings.

And sharpening off.

A Golden Sky

Last Thursday in the ongoing pursuit of bargains, I took a break from more serious errands after I spotted a garage sale sign. A good number of blocks later without passing a garage sale I was about to turn around.  Then I spotted a second sign. Since it was mid afternoon of a blustery rainy day the sign was half blown over and not immediately readable from the car.  But since its road only went one way I turned and headed down the side street.

This time I drove several winding looping blocks without a hint of a garage sale.  Then I came on an entrance to one of the city's many neighborhood parks. For the moment it wasn't raining and my D7000 kit was on the back seat so I stopped to explore any photo opportunities. And found this addition to the photographic genre, atmospheric skies.

Yes, for the zillionth time I forgot to switch the white balance to auto after I finished shooting indoors under compact fluorescent lighting.

But that is what the white balance dropper is for. I clicked in the circled area.

And ended up with this image

Sort of what I was after--an essentially monochrome RGB image. But it lacked that extra punch.  I decided to experiment and see how well RT could tone this image.

The HSV flat field editor in the color tab had worked well on other more colorful images.  A disappointment here. With so little color to work on, I saw only a slight shift towand red.

I went back to my tried and true toning procedure-LAB mode in the exposure tab. As I've blogged about earlier the b color channel controls the ratio of the two complimentary colors, blue and yellow. Took only two simple drags to adjust their ratio and few more slider adjustments to fine tune the image.

A couple builds back I would have stopped here  but there was one more routine to try, the channel mixer.

Because of bugs it hadn't worked as expected the last time I tried it on some infrared images. But according to the RT forum, all those bugs had been swatted in time for the latest 4.0.3.4 build.

Nobody fibbed.  I moved the slider around without any particular plan or science until I found a richer color than I had using the LAB mode.

The  final image.

So download RT and try it on your images. You won't be disappointed.

PS. On my way back, I passed the garage sale a couple blocks farther down from where I made the wrong turn. Bought a neat junk/ treasure that will be used-a heated coffee carafe complete with a thermostatic control that varies the temperature from just lukewarm to burn you tongue.

Now, while I drive on a photo day trip, my coffee fiend of a wife can sip her favorite brew as she scans to countryside for more photo opportunities.

Serendipity,  wouldn't you say.