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Photographer's Note

TrekEarth is all about learning abut the world through photography – and also learning something about photography as we go along. So here’s a good example of something I have learnt today – at least about the post processing of my images.

When I posted the original of this image two days ago, I mentioned in my note that I had attempted to sharpen it unsuccessfully, because it introduced too much noise, and I just assumed that it was because the image was already very soft being shot through light rain. (I tried to sharpen using USM in Photoshop Elements but it introduced a lot of noise that I was unable to satisfactorily remove with NeatImage). But then along came another TEer – in the form of Christian Cooper (gary91) – and proved me wrong.

Christian did a workshop that showed it could be sharpened nicely without introducing a lot of noise. So what did I do wrong? I thought maybe it was the noise removal software we had used. He had used Noise Ninja, whereas I had used NeatImage. So I logged onto the Noise Ninja website to find out more about that particular software and noted the following response to a question in their FAQs:

“Q: Where should Noise Ninja be used in the workflow?

A: It is usually best to apply noise reduction as early as is practical in the workflow. Post-processing adjustments like sharpening, contrast stretching, and colour balancing can alter pixel values and noise levels in unpredictable ways. Depending on the amount of adjustment, this can make it more difficult for Noise Ninja to estimate noise levels. Sharpening, for instance, is a nonlinear operation that can significantly distort the distribution of noise values.”

Ah ha! That’s what I did wrong. I tried to remove the noise AFTER sharpening. Whereas Christian, according to his note, and as recommended in the Nose Ninja FAQs, removed the noise BEFORE sharpening.

So back to my computer and I tried the PP again, this time altering the order of the workflow. And it worked. The image I have reposted is very close to what Christian produced in his workshop. There is a difference though. I had to use USM at 500% and a radius of 2.0 pixels to achieve the same level of sharpness that Christian had achieved at 110% with a value of 0.3. Perhaps that was because of the different noise reduction software that we had used at the first stage in the workflow, or maybe it was something to do with the fact he was working with a 200kb jpeg file whereas I was working with a 9MB tiff file.

The learning continues . . .

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Additional Photos by David Astley (banyanman) Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 1237 W: 108 N: 2568] (7789)
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