Adobe Photoshop Training with Dan Margulis

I know I'm pressing the envelope for acceptable topics here, but I hope this problem will intrigue some of the creative thinkers on this list.

If you have had occasion to restore old prints you have probably had to remove a random peppering of dark spots at one time or another. There is an example of such peppering on my web site at: http: //www.lutzphotography.com/webspots.jpg

I have two questions:

First, what causes the spots? The prints are usually old (80 + yrs) B&W (toned or not).

Second, is there a clever way to remove them en-masse rather than individually with the clone or healing brush tools?

Dick Lutz

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Brown-ish spots like this are often caused by iron impurities in the emulsion. This used to be quite a common QA problem in the days when glass plates were made using the local water supply, and I suppose the same issue affected paper emulsions as well..

Photoshop's dust and scratches (D+S), which is a thresholded median filter, was designed to remove just this sort of noise. I find a setting of radius 3, threshold 10 gets rid of the small dark dots in your image quite nicely.

The trick with D+S, as with any noise reduction filter, is to stop before you start to erode actual image detail. Detail tends to cover the dots, so sometimes I select areas of low detail with the lasso tool, and filter these selectively.

You could get a serviceable result at this point by simply pulling out the red channel but there is more that can be done regarding the more diffuse, yellowish blotches.

In your sample image, the dots are colored, and there an immediate improvement results if you simply drop the overall saturation of the image. You may be able to experiment with using, say, the blue channel to generate a mask to select out the dots.

Mike Russell

www.curvemeister.com

www.geigy.2y.net

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When I read Dan's book he mentioned that fixing blemishes in LAB will work good.

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A real easy way to get rid of the spots is as follows:

1. Make a copy of the image on a new layer

2. filter - blur - Gaussian blur of about 4 or 5 pixels to completely blur the new layer which will be on the top to the point where the dots blend in with the rest of the picture.

3. Move the blurred layer below the original layer.

4. Selectively erase those areas exhibiting the problem on the original layer exposing the blurred sections from the layer below it.

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From: "Mike Russell"

I'll add that if you do the D&S, use a duplicate layer so the process is reversible, then you could play with the 'blend if' sliders to make sure that you do the least damage.

john c.

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I don't know what causes them, but have you tried the Polaroid Dust & Scratch Removal software available free from

http: //www.polaroid.com/service/software/poladsr/poladsr.html? At very low settings, it eliminates most of the smallest spots with only a barely noticeable (if any) increase in image softness. Then cloning or healing the larger spots is much easier. I use it frequently, and though not perfect, it's really good.

Preston Earle

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One can also do something similar using the history brush.

1. Apply the desired filter to decrease or blur the spots.

2. Set the origin in the history pallette on that history state.

3. Set the destination the history state before the filter was applied.

4. 'Paint' the spots with the history brush effectively painting the

filtered version of the image onto the original.

Lanny Lathem

Bennett Graphics

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Lanny’s is the better of the suggestions I have heard. :-)

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Thanks to everyone who replied. Nearly everyone recommended the noise filter, dust and scratches --in combination with the history brush. This did the job. For anyone interested I posted a before and after at: http://www.lutzphotography.com/webspots.html

It was suggested that "foxing" is the term that describes these spots on old prints. The recollection was "right on". Google provided this link to a description of foxing:

http://palimpsest.stanford.edu/don/dt/dt1434.html

Preston E. recommended trying Polaroids free dust & scratches software, available at:

http: //www.polaroid.com/service/software/poladsr/poladsr.html?

I gave it a try and thought I might mention two things. First, you have the option to download both a plug-in to run in your current version of Photoshop and a separate dust and scratches application which runs apart from Photoshop. On my system (Os X.3 and Photoshop CS) the plug-in would freeze Photoshop every time. The application software however, worked very well. Second, the dust and scratches application worked first by selecting the spots and then removing them. I would like to know how to select the (small pepper like) spots. A couple of you mentioned selecting the spots. How would you do it?

Dick Lutz

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hello dick, could not view your before/after, only the copyright Lutz was viewable . I believe the majority of your spots were just plain old dirt, although they did look a little like something that was in a fire/got damp-wet.. caught a little soot... I think foxing is associated with moisture/fungus growth.. looks dusty in spots.. and when you brush the dust away (on the emulsion side).. the image goes with it... jim bean

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Sorry, Jim. See if this works:

http://www.lutzphotography.com/webspots2.html

You'll have to scroll down to see everything. I'd be interested to know which OS and browser you use if you don't mind contacting me off list. For my email address replace the and with an @ symbol. rlutzandavalon.net

Dick Lutz

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Dick Lutz writes,

The recommendation is a good one, but one thing should be added: if you are trying to erase large blobs of dark noise with the Dust & Scratches filter, you tend to erase a lot of delicate white detail that then has to be restored with the history brush or a layer mask. The solution is to run the Dust & Scratches layer in Lighten, not Normal, mode. It may be necessary to darken the top layer very slightly to further restrict its action. If this is done, further retouching will be sharply reduced.

If you are happy with the "selection" made by Dust & Scratches, you can save it as a mask and use it on the original image later:

1) Make copy of image.

2) Make two duplicate layers.

3) Top layer, Dust & Scratches.

4) Set top layer to Lighten mode.

5) Merge top two layers.

6) Set the new merged layer to Difference mode.

7) Flatten image.

8) Auto Levels.

9) Slight Gaussian blur as customary in masks of this type.

10) Convert to grayscale and save.

Dan Margulis

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Thanks, Dan.

That's just what I was looking for. I posted (temporarily) an example of the mask at:

http://www.lutzphotography.com/webspots2.html

Dick Lutz

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Thanks Dan.

Posts like this make it worth sticking around here in spite of the abuse!

john c.