Google| Subject | Re: Any Minolta/Sony users using UFRaw and GIMP? |
| From | Floyd L. Davidson |
| Date | 04/08/2014 12:11 (04/08/2014 02:11) |
| Message-ID | <87ioqk5dws.fld@barrow.com> |
| Client | |
| Newsgroups | rec.photo.digital |
| Follows | Eric Stevens |
| Followups | nospam (2h & 52m) |
Eric Stevens <eric.stevens@sum.co.nz>wrote:
Eric Stevens"Clark Vision have published articles describing their tests with all these things using Photoshop. See for example"
On Mon, 07 Apr 2014 17:54:30 -0800, floyd@apaflo.com (Floyd L. Davidson) wrote:Floyd L. DavidsonEric Stevens
nospam <nospam@nospam.invalid>wrote:nospamFloyd L. Davidson
In article <87a9byohta.fld@apaflo.com>, Floyd L. Davidson <floyd@apaflo.com>wrote:nospamEric StevensFloyd L. Davidson
Clark Vision have published articles describing their tests with all these things using Photoshop. See for example http://www.clarkvision.com/imagedetail/image-restoration2/index.html>
Read it a little closer Eric, Roger Clark did not use PhotoShop for Richardson-Lucy Deconvolutional sharpening, he also didn't even mention the Wavelet sharpening that I have previously commented on.
read it closer yourself. what he *didn't* use was the gimp.
Nobody said he used GIMP. But Eric said he used Photoshop, which was not even close to true.
I did not say the article I cited described how he did all these things with photoshop. I said he has published 'articles' (note plural) and cited this one as an example.
The one example does not show what you said, and specifically says otherwise. The other articles that Roger Clark has published don't either.
Oddly enough, given two or three other comments you've made, it does appear that you may be the only one responding on this topic that actually does understand the significance of these various algorithms to photographers!
In particular, you suggested this well written article:
http://keithwiley.com/astroPhotography/imageSharpening.shtml
Which near the end has this statement:
"By strengthening a mask in a "high" layer corresponding to a small blur, you increase the Mach bands in the small features (generally called high frequency components of an image for obvious reasons). By strengthening a mask in a "low" layer corresponding to a large blur, you increase the Mach bands in really large features"
How many here will recognize that as essentially saying that wavelet sharpening gives you the same effect as using both USM and HP sharpen together? Except that with wavelet sharpening the algorithm spreads it over the entire range, not just at two specific spatial frequencies.
I usually have described that by saying an high pass sharpen tool works on multiple transitions in sequence, while a USM tool works on single transitions. Both have a very high frequency component, but with a different energy distribution.
This is not just an off the wall discussion of theory, it's about how to get better photographs!
Or, one can do what Savageduck did, citing two images to demonstrate exactly the point that I made: most readers here (and specifically him) are completely unaware of the significant distinctions in how and how to use different sharpen tools or why there are different filters than "Smoother" and "Sharper" for Bicubic resampling in good software tools.
-- Floyd L. Davidson http://www.apaflo.com/ Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
04/05/2014-
