[davidknibb]

Hello
I hope I'm posting this query in the correct forum - if not I apologise.
Over the past year I've been scanning many thousands of old transparencies on my Minolta Scan Multi 2. (No digital ICE). Most of the scans are acceptable - and can easily be cleaned and touched up using standard Gimp tools.
However one or two batches have shown signs of massive deterioration. The have literally thousands on pin head size brown stains - caused I think by faulty processing at the washing/drying stage (Ektachrome Film).
I've no idea how to handle this in Gimp and would welcome some ideas if there any friends out there who have also had this problem.

I do know how to do it in PhotoShop - briefly its
Dust & Scratches Filter (which also significantly softens the picture overall)
Take Snapshot in history panel
Set history brush to the Snapshot
Set base picture active
Cover frame with brush - usually set to lighten

Is it possible to replicate this in either Gimp 2.2 or 2.3.8 ??

I've also got the Polaroid tool (no longer produced) - which works quite well. Could this be set to be a Gimp Plugin does anyone know ?

Thanks for all ideas and suggestions

David

[saulgoode]

Check out the "Despeckle" filter. There is no "history brush" in GIMP (yet) so I would advise duplicating your layer and applying the filter to the copy. You can then create a layer mask on the top (filtered) copy and paint on the mask with either WHITE to show the filtered layer, BLACK to show the unfiltered version, or any gray value to mix the two layers.

If you can post a sample image or two, perhaps some of the members here can provide some customized tips.

[davidknibb]

Thanks. Here is a typical example. The deterioration can be seen in the sky - and if you zoom in on it - the dots can be seen all over the canvas.

David


D:\Germany\1989\Austria8902.jpg

[davidknibb]

H'm - haven't got the knack of posting an Image have I ? Not sure what I did wrong - try again

David

[davidknibb]

See if this works


D:\Germany\1989\Austria8902

[XyllyX]

Ummm....you posted a link to a file on your local hard drive. No good. Get an account on either photobucket or imageshack (I use imageshack) You post your pick there and they give you some nice link code you can paste in the forum.

As for fixing the image... I have never used despeckle, so I dunno how well that would work. You could always do a lot of work with the clone tool, be real time consuming.

[davidknibb]

Ok - thanks for the advice. I think I've uploaded to photobucket - so here it is. As you can see there are thousands of pin head dots. Since I've got 2*36 of these, I dont really fancy the clone tool.



Thanks for all help and advice

David

[saulgoode]

"Despeckle" seems to do the job quite nicely.

[davidknibb]

Yes - thanks for the reply. I had already been using despeckle - but notice that in cleaning the picture it always softens all the rest of the picture. I waslooking to see if there is a way of removing the damage - and mantain the sharpness of the rest of the picture. I know I could sharpen after despeckle - but that also distorts in a way I don't really want.
(The Photoshop approach I outlined keeps the general sharpness of the rst of the picture - which is why I wondered if there is a way to emulate it using the existing Gimp tools. I have access to Photoshop - but for matters of pride if nothing esle try to do everything on Gimp)

As a matter of interest what parameter settings did you use for depseckle ?

Thanks for the interest & help.

David

[saulgoode]

Generally, the speckling is more apparent in the lighter areas of the image so after you have filtered the top layer, add a layer mask from the "grayscale copy of the layer". This will make the unfiltered bottom layer appear whereever the image is dark (I have replaced my previous image above with just such a masked version). You will also be able to paint the layer mask (as I described in my first post) to adjust things manually.

The settings I used were the defaults, except that I checked the "Recursive" box (Radius=3, Black=5, White=251; I think).

[PhotoMaster]

Hey Saulgoode,
Great job on that one! I would not have thought of that! I was trying to clean it up by manually making a selection and and applying the filter only to the selected area. Your solution came out better, was faster and a whole heck of a lot easier!!!

Greg

[davidknibb]

Thanks a lot for the help - a good solution. It still seems to soften the picture a bit - obviously the less powerful the despeckle - the less the picture is softened.
A very close look at the Photoshop method - and the PolaDSR method also show some softening.

i wonder if there is any way that avoids softening this completely - apart from something like clone.

Something like finding all pixels that are the 'dot' colour - and replacing them by the nearest adjacent pixel that isn't that colour. Obviously this would be easy to fool if there were genuine pixels that colour - they would have to be selected out.

I know nothing about working at pixel level in Gimp - or even if what I proposed is possible.

David