Evaluation of Polaroid Dust & Scratches Utility

Polaroid now has a free utility that reduces dust and scratches in digital images. It operates as both a plug-in within Photoshop, as well as a "stand alone" version which gives you much more control, best of all it's available in both Windows and Mac (OS9 + X) versions.

To give you a quick evaluation of whether this utility might be useful to you read on. The help file provides the following:

In the plug-in, the defect detection and removal is done in one step. You can't generate a defect mask and then modify it prior to cleaning the image.

• The various tools (selection, manual dust and scratch marking) are not available in the plug-in. To select a region for correction, use the selection tools in Photoshop prior to running the filter.
  
• The plug-in has a live preview feature. As you adjust the controls, you can see the effect on the image.

The key is to set the items in the "Defection parameter" dialog box correctly.

I used this utility on a couple of color negatives that I had recently scanned. They happened to be from 400 ISO speed Portra negs, if that makes any difference to those reading.

First off, the good news. The stand alone software will actually work on "high-bit" images! (16-bit per channel images in Photoshop-land) as well as 8-bit images. It also works tolerably well on images with well defined dust spots.

The bad news. It's not as effective on scratches as I would like to see (at least not compared to using the clone tool, or the "copy and paste from a nearby area" trick). It's not very effective on older film with separation "scum" or other less defined defects. And it works best if you manually select all the spots where you want the software to create the dust "mask."

In this first sample jpeg (175 kb) you can see how the "auto mask" works compared to a Photoshop-only technique. This process uses the "Dust & Scratches" filter applied only to a second layer while using a layer mask to selectively show the filters, effects.*

I found that if I manually placed all the cues for the dust mask and scratches, I got much better results than using the auto command in 16-bit, and figured the high bit file might be the reason why.

Look closely at the scratch, there appears to be a "smear" that makes the pixels darker. In the original TIFF it's a little more noticeable. This and the other image mentioned below were compressed using the SAVE FOR WEB feature as Jpegs using level 61 (high) and have the colormatch RGB ICC profile attached. You may want to download and view in photoshop rather than view in your browser only.

In this second sample jpeg (507 kb), you can see how the auto settings work for both the regular and the "adaptive" filtering option. These were done using the "light" setting as this was a scan from a negative, and most dust would show up in the lighter areas.

The help file says this about the adaptive filtering option.

Adaptive Filtering
When this option is selected, the luminance of the image is taken into account when searching for dust. This can prevent dark image detail from being identified as dust. It is, however, slower.

I only had a chance to try it on one older slide scan that I've been putting off as it had been trashed when it was scanned from the original publication. It didn't fare much better than using the dust & scratches filter in Photoshop.

Conclusion
The stand alone software would be great for those users without access to photoshop. Otherwise, I still think you can get as good a result using the standard dust & scratches filter in photoshop. AND you can get even better results applying this filter to a duplicate layer and using the layer mode and layer mask so that the effect only shows through on the parts that are affected.*

Of course, this is simply one users report. If anyone else has more time to play around with it, please let me know what you find out.

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If you want to try out what I'm suggesting, the image needs to be at 8-bit.

Step-by-step way to eliminate most dust from an image:

·From the Layer menu (or Layer flyout) choose "Duplicate Layer."
·Select the duplicate and apply the filter (in this case, Filter > Noise > Dust & Scratches).
·Play with the settings till you get a version that makes the spots go "bye-bye."
·Set layer to lighten (if a transparency with dark dust) or darken (for white dust).
·Go to Layer > Add Layer Mask > Hide All (spots will reappear as you are hiding the dupe layer)
·Select the black box next to the image in the layer palette.
·Click on paintbrush tool, choose appropriate sized brush, and paint over spots.
·Save a version as a PSD file in case you need to go back and "revert" some of the dust spots (or to show your client how much work you had to do on their file).
·When you are happy, flatten and save as TIFF.

Don't forget that you can also do a search of Photoshop's "Help" menu whenever you don't/can't find one of the tools within photoshop. The added benefit, is that you usually learn something new that you might not have otherwise.

BTW, if you are trying to do this in 16 bit, you can't, as it involves layers (which PS doesn't support in High Bit mode). Based on what Jeff said at DIFP, you could do a variation on my method by duplicating the image, dropping to 8-bit, applying your filter, saving that history state, and dragging it to the 16-bit image and then painting from history. It's only reversible while the image is open, but might be worth experimenting with.

©2003 David Riecks, please do not distribute without permission from the author.

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This page last updated: 1-7-2003