Good to know. Thanks for this. Paul On May 26, 2011, at 7:50 PM, Bruce Walker wrote:
> On 11-05-26 6:08 PM, John Sessoms wrote: >> From: John Sessoms >>> Ok, so I had a go at seeing what I could do at restoring the image using >>> the tools Bruce linked to. >> >> Never mind. I took another look at the corrected image Bruce had posted and >> took my attempt down right away. >> >> Got to install imagemagick & see if I can figure out how to use it. >> >> The Photoshop plug-in doesn't seem to work as well as imagemagick. > > John, I believe they both use the same FFT engine, the opensource project > FFTW.org, so I'd expect that they should work about the same, given the same > inputs. > > What did your spectral mask look like? You may not have removed enough > points. I iterated on that image a couple of times, removing more spectrum > each time before I was satisfied that I'd suppressed enough of the original's > vertical lines. > > Here's the image I got for the frequency space in Dave's (leveled and > cropped) original: > http://dl.dropbox.com/u/2254722/picture0001_spectrum.png > > And here's the mask I ended up with, created in Photoshop by painting black > onto a white layer with a 10% hard brush: > http://dl.dropbox.com/u/2254722/picture0001_spectrum_mask2.png > > You don't want to allow any hard edges in the mask as that will create new > artifacts (especially ringing near any edges), so you must either use a > soft-edged brush or apply Gaussian blur to your mask before applying it. > > When creating the mask I looked for anything in the frequency-space image > that seemed regular and symmetrical. Normally an image like that (especially > such a soft one) should have a pretty uniform and random looking spectral > distribution, so any dense white clusters or stars are suspect. As you can > see I was fairly sloppy with my hand drawing of the mask, but it doesn't seem > to matter all that much, so you can fairly safely err on the generous side. > > A quirk of the FFTFILTER script is it expects the input image and the mask > image to be the same dimensions, so I expanded the canvas of the original > image (to 2092x2092) making it square, with black bars above and below. > http://dl.dropbox.com/u/2254722/picture0001-2092.png > > When you install ImageMagick on your computer, make sure that the FFTW > library is already installed for it to find, or it won't be able to do any > FFT operations. If you get error messages when trying to run the script, > Googling on those messages will get you lots of help on the proper > configuration of this stuff. > > Good luck! > > -bmw > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
