Monday, February 20, 2012


By Madison in Febuary standards last Saturday was balmy. Despite the sunny, mid 40's weather my D7000 and I spent the afternoon indoors at the Olbrich Garden photographing the Children of the Rain Forest.

This month's performers were the Hale O Malo Polynesian Dance Group, Their costumes and dances ranged from a New Zealand  Maori war dance to a Tahitian fertility dance. That invocation of human fertility came with a friendly warning, "Do not attempt this at home."

This image was shot during the pictures-with-the-kids session at the end of the show using my new Tamron 18 -270 mm f3.5-5.6 super zoom set at 18mm wide angle.  The manual exposure settings were f8 and 1/200 sec combined with an auto ISO. That ended up at 6400.

Not an optimum or necessary ISO for this image. It could have been much lower.  At 18mm the lens opens at f 3.5. For a static shot a shutter speed of 1/60 sec would have worked. But I had set up the camera for telephoto dance images, 1/200 sec to give a sense of motion without excessive blur and f8 to sharpen up the lens's slightly soft long end. I didn't spot any massive noise problems when I reviewied the screen shots during the shoot so I went with the default settings.

For post processing I downloaded RAW Therapee's latest 64 bit build, version 4.7.01. It doesn't have the new noise reduction routines yet, but it does have enough new features to  justify a build jump from 4.6 to 4.7.  I'll talk about a few newfeatures in this post, plus some older ones that I haven't used much, starting with the big review images in the file browser.

With dance groups I tend to over shoot.  You know, long continuous bursts hoping to capture that perfect combination of step, twirl and jump. This time I filled my 16 GB main card and moved down to my 8GB secondary card. There I found Miss Thumps-Up posing for Mom's perfect snap combined with an interesting environmental background.

Viewing the preview jpgs full size on my laptop screen while using the number and color coded ratings sped up my selection workflow. I ranked my 'maybe images' during a first pass and then fine tuning the selection set. Definitely a winner.

Judging by the curve of the molding board at the top, this image, shot at 18mm, has serious wide angle lens distortion.  So I tried the fix in the Transform/lensgeometry/distortion tab. My first guess, a -0.5 pincushion setting went way over the top. But it did open up ideas for some creative playing around later.

The for real setting was -0.09.  I pulled up a grid Guide Type to provide straight lines as a reference. At the moment the routine bends the image only one way and creates a curved blank area at the bottom. So I used auto fill to clean up that problem. And for those interested in composition rules the Guide Types include rule of thirds, rule of diagonals and several harmonic mean or, as I used to call them, golden sections.

With the proper settings I created an '18mm tamron' default profile that I can call up to automatically correct my wide angle images.

This fixed I tried out a  new profile that came with RT 4.7-- 'default ISO high'. After I applied the profile  it was  'WOW!! Where has all the ISO 6400 noise gone!!?'

Turns out the RT team had done some interesting things but the real WOW maker was my serendipitous mistake. I'd been working with the jpg not the NEF file, a jpg that had already gone through one pass of the Nikon D7000 excellent in-camera noise reduction routine.

I posted twice last August about how well RAW Therapee works as a jpg editor   My mistake turned up another use- one that is especially helpful to someone who shoots flash-less low light party and people photos.

Here is the most interesting settings in the 'default ISO high' profile along with my modifications.

I left the Impulse Noise Reduction at 80. Luminance comes up as 0 so I set that to 20. Gamma 1.2 has the effect of shifting noise reduction into the shadows where it is needed the most. As usual the effect of all this is to blur detail (bad) while removing noise (good).

The RT folk's ingenious addition is to use 'contrast by detail levels' to recover a surprising amount of the blurred detail. The default values are 0 (finest) =1.00 and the next level '1' =2.00 but at the time I was thinking noise rather than detail;  So I may have gone a little too far fiddling with the sliders and cut out slightly more detail than the noise reduction needed. Either way, the noise cleanup and preserved detail  on this ISO 6400 image is dramatic.

How dramatic. Here are my results. And unlike the Tahitian fertility dance you should definitely try this at home.

The image on the left is from the NEF using the current noise reduction routines. It has the highest noise. It also has the most preserved detail in the girl's hair so I could have pushed its noise reduction harder.  The middle image is the jpg from the D7000 using its default jpg (Sd) and noise reduction (norm) settings. While I wouldn't have called it bad a week ago, now it looks flat and washed out next to the RT image on the right. I lost some detail in the hair but with the noise now so low I can print it up large, perhaps to 11 by 14, without showing objectionable noise. Not shabby for an ISO 6400 image.

Lesson learnt. At the moment there is no advantage working from NEFs using RT. Not that this is a massive bash; the D7000 has one of the best in-camera noise reduction algorithms around. And judging from the comments in the forum, RT should get better soon. See Issue 1052: New luminance NR algorithm  for up to date details.

With a CPM member's show coming up and several low-light images I'm considering exhibiting, it is time for some serious post processing. Will let you know how everything works out.

PS. The line profiles were taken off the wall over the girl's shoulder.

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