[Digikam-users] sharpening & noise reduction workflow

Wilkins, Vern W vwilkins at indiana.edu
Mon Dec 21 16:37:42 GMT 2009

So I've been looking at the noise reduction options in Digikam 1.0.0 and I'm starting to wonder what the best workflow is for combining noise reduction and sharpening.  My old workflow was something similar to the following (I left out everything not related to noise reduction and sharpening).

1. Convert RAW w/ Ufraw, and minimal amount of wavelet noise reduction
2. Use refocus sharpening in Digikam, typical setting might be .80 circular sharpness, .4 correlation, .007 noise filter, 0 Gaussian sharpness, and 12 Matrix size.  The circular sharpness and noise filter are the only settings I changed often.  I'd sometimes go as high as .010 for the noise filter with high ISO images, and combine that with a lower circular sharpness.  Even with low ISO images I generally don't go less than .007 on the noise filter, but sharpness might go as high as .85.  In my experience, keeping the noise filter low, allows me to use a lower circular sharpness, and it seems that increasing the noise filter, just requires that I have to increase circular sharpness more.

Anyway, what I'm considering is using the new advanced noise reduction in Digikam 1.0.0.  So my new workflow might be something like this.

1. Convert RAW w/ Ufraw, no wavelet noise reduction
2. Use Enhance/Noise reduction in Digikam to reduce noise (what settings I don't know yet)
3. Use refocus sharpening. (settings would likely be different from previous workflow)

I'm assuming I can get better results with this method but I haven't begun to experiment with settings.  Does the order seem reasonable here?  It wouldn't make sense to sharpen before doing noise reduction would it?  Is it likely I could use a setting of 0 for the refocus noise filter, if I'm using noise reduction prior to this method of sharpening?  Anyway, I'll get back to the list when I've had more time to experiment with various combinations, but I was just curious if anyone had any good starting points, compared to what's in the handbook.  The example settings in the Digikam documentation seem relevant if you are only reducing noise, or only sharpening, but not when you are using multiple tools in your workflow.


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