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Dust busting scans

Dust is the enemy of photography. Every time I go to print or scan a negative and find dust on it, I consider switching to digital. Then I remember all the stories of people with dust on their sensors and having to correct hundreds of files. At least you can automate that.

The first and best way to obtain dust and scratch free scans is to have dust and scratch free negatives. Sometimes scratches happen and are unavoidable. But dust and water marks can usually be minimized. For water marks, use Photo-flo or a similar solution. I use it as described on my Film Processing page. Then hang your negatives up to dry in a dust free environment and handle them carefully after they are dry. Mine go immediately into sleeves for flattening, and only come out for scanning and printing.

Removing dust and scratches

Invariably, you will have some negative with dust and scratches. Now we have to remove the defects.

Fixing before the scan

If you do have some dust on your negatives, 20 seconds of work before you scan can save a lot of time. Get an air blower like a Rocket Blower or similar used for cleaning digital sensors. Blast your negatives before scanning. Even if you don’t inspect them closely, a couple quick puffs should remove large pieces of lint and dust and save you time later.

If you are willing to spend a bit more time, inspect your negatives by bouncing a light source off of the negative surface at an acute angle. If you see anything, flick it off with a fine tipped brush. You can get them at a craft store for a dollar or two.

The healing brush

Back in the day, all we had was the clone stamp tool in Photoshop. Now we have the healing brush. Use it. It handles the worst of your dust and scratches. Some areas might need the clone brush still. I’ve noticed you need to resort to the cloning tool when there is a blemish on a dark/light transition on the negative. The healing brush usually doesn’t get that right. But it’s great on areas of more continuous tone.

I just upgraded to CS5 and the ‘content aware’ option on the healing brush is really useful.

ICE

Scanners with Digital ICE are great. They can really save a lot of time dealing with dust and scratches on chromogenic films. It doesn’t work as well on Kodachrome (almost a moot point now) and not at all on B&W film. It does seem to affect sharpness all over the image on a minor level. This may or may not be an issue for you.

Dealing with RGBI files

However, Vuescan can save the IR channel in scans. I have a Photoshop action which processes this and makes it useable. It’s probably comprable to what ICE does, or what some of the 3rd party scanning programs do. The downside is that it takes some user input to deal with things, which ultimately takes your time. The upside is that it takes user input, which means you can selectively apply it to only the areas that are affected.

An added benefit of this user intervention is that you can use it on RGBI scans of Kodachrome. While I’ve never used it, apparently the Nikon Coolscan 9000 has a Digital ICE that can be used on Kodachrome. The Coolscan V does NOT. You can use it, sure, and it will fix dust and scratches. It will also ‘fix’ many dark/light transitions as well.

The Photoshop actions

This action set will let you process the infrared channel of an RGBI scan. The infrared channel is just stored as an alpha channel. It’s pretty low contrast, so in its regular state, it’s pretty useless. The first action in the set (Prep IR channel) prepares the infrared alpha channel by boosting the contrast and expanding the zones where dust and scratches appear.

The action Dust Bust - Spot Heal makes a layer above the base layer with the modified IR channel as a layer mask. It also auto selects the ‘spot healing brush’ tool. You can basically start using the tool on visible blemishes with the tool. Sometimes it helps to look at the layer mask to identify where the blemishes are.

The action Dust Bust - Spot Heal large is the same as the he action Dust Bust - Spot Heal except for the fact that it expands the area for the detected blemishes. I hardly ever use this action.

The action Dust Bust - D&S applies a ‘Dust and Scratches’ automated filter in an adjustment layer with the modified IR channel as a layer mask. This catches a lot of small blemishes and most of the large ones, but the handling of the large blemishes can leave something to be desired. I prefer to run this action after the Dust Bust - Spot Heal action but put it under that layer to catch anything I might have missed. This way the hand corrections done with the Spot Heal layer overlay any automated corrections done with the ‘Dust and Scratches’ filter, which can look a bit poor sometimes on larger blemishes.

The Healing top layer action just makes a layer on the top and selects the normal healing brush tool. You can use this to fix any blemishes that weren’t caught by the more automated tools.

Lastly, the Dust alpha removal just deletes the IR alpha channel.

I typically run them in this order:

  1. Dust Bust - Spot Heal — correct large blemishes
  2. Dust Bust - D&S — put it under the above layer
  3. Healing top layer if necessary to catch anything that wasn’t picked up
  4. Dust alpha removal
  5. Merge or flatten the dust layers onto the base layer if you satisfied with things

The action set is here.