Dust Spot Removal – The Digital Photographer’s Nemesis
By Sean Bagshaw
The nemesis of today’s digital photographer is dust spots. Despite our best attempts at sensor cleaning and even with the introduction of sensor cleaning modes in our cameras we inevitably end up doing spot removal as part of our image processing workflow.
In fact, as part of the non destructive digital processing workflow that I teach, spot removal is the first thing I tackle once the image has been opened in Photoshop. The best time to remove spots is at the bottom of the layer stack either on the background image or on a cloning layer directly above the background image. Cleaning up the image before moving on to other developing procedures is really important. Depending on what type of developing techniques you use on an image it can be anywhere from difficult to near impossible to remove dust spots without leaving artifacts at later stages in the process.
However, even when I do a careful job of spot clean-up I frequently miss some. Often there are spots that are so faint they are nearly invisible in the undeveloped image but show up several steps down the line after adjustments to contrast, luminosity and clarity have been made. At best, I notice them and can remove them without too much time and trouble. Worse is when I have to back track several steps in my processing to remove them and start over from that point. The worst is when I fail to notice them at all until I have already enlarged and printed the image and find them jumping off the page at me.
Fortunately there is a simple way to preemptively combat this annoyance through the use of what my friend Mac Holbert calls a “revealing layer”. Taking the extra few seconds to use a revealing layer has saved me much time and many headaches in the long run. Here is how it works:
- With the unprocessed image opened in Photoshop add any type of adjustment layer that can be used to increase contrast. I like to use a Curves adjustment layer and use an “S” curve to boost contrast. You can also use a Contrast/Brightness adjustment layer, a Levels adjustment layer or even a Curves adjustment layer with the blending mode set to Overlay. Whatever you do the point is to crank the contrast way up.
- The enhanced contrast should make all your dust spots jump off of the screen at you, even the ones that were previously so faint as to be undetectable. Now select the background layer and view the image at 100% magnification. Scroll through and remove dust spots with the technique of your choice. In CS5 the Spot Healing Tool set to Content Aware usually does the best job.
- Once you have removed every last spot simply delete the high contrast “reveal layer”. Now you can continue with your workflow confident that you have removed even the wiliest of those suckers and none will be showing up to surprise you after three hours of work.
- If you prefer to do your spot removal in Lightroom you can use the same basic concept. Use a combination of the Contrast slider and Clarity slider to boost contrast and make even the faintest spots show up. Remove them with the Spot Removal tool and then set the Contrast and Clarity sliders back to where you want them.
If you have any questions for me or your own spot removal tip you’d like to share please leave me a note in the comments section. I’d love to hear from you. Cheers!