How to rid your close-ups of dust and scratches with Photoshop
One of the challenges of close-up photography is to capture a small object as pristinely as possible. Human eyesight is no match for a powerful camera lens. Once you import your photos and view them full screen, you’ll notice objects that looked spotless to the naked eye are in fact littered with dust, fibers, and other imperfections.
This is something I struggle with daily as a toy photographer; sadly, no amount of careful cleaning and dusting can guarantee a flawless photo. Adobe Photoshop includes a number of excellent tools to help you scrub your close-up shots clean. (This article uses Photoshop CS6 as an example, but many of the tools referenced can also be found in both Photoshop CS4 and CS5, as well as recent versions of Photoshop Elements. Apps like Pixelmator 2.0 and SnapHeal also have great tools to help you clean up photos.)
Spot Healing Brush
The first weapon you’ll want to wield against errant dust and rogue fibers is Photoshop's Spot Healing Brush, which repairs spots using the color and texture in the surrounding area. It’s also rather good at repairing small nicks and scratches on the object itself.
Open your photo and zoom in to 100 percent. Now choose the Spot Healing Brush (Band Aid icon) from Photoshop's tool panel. You’ll want to set an appropriate size for the brush before you get to work. Control-click (or right-click) the canvas to call up the brush options, choose one of the default round brushes, and adjust the size to 10 pixels (or smaller). The panel’s other settings are usually fine for most touch-up work:
• Hardness=100 percent
• Spacing=25 percent
• Angle=0 degrees
• Roundness=100 percent
You might also notice three brush types in the tool options at the top of the window: Proximity Match, which examines the pixels around the brush stroke you make to determine a patch source; Create Texture, which looks only at the pixels within the brush stroke to create a pattern fill; and Content Aware, which samples nearby areas to maintain the color, luminosity, and texture within the targeted area. Content Aware is the default brush method and the most effective—it also detects and attempts to rebuild edges and seams—so make sure it is selected before you continue.
Once you’ve sorted out those settings, find a dust speck that sits in the midst of a somewhat uniform area; it can have texture, but it should not be bordering a seam. A single click of the brush should eliminate the spot instantly. Now look for a small scratch, hair, or fiber on the object. This time, click and drag the brush, snaking it along the shape of the debris. It too should disappear instantly. Keep attacking dust and debris with this tool; in a few minutes, you should have a handle on how it works.
The Spot Healing Brush can be unpredictable along edges or seams. In these situations, you might find that the brush works better if you click and drag clear across the edge or seam, rather than just clicking it once. Always avoid dragging the brush in a squiggly motion across a seam, because this will result in either wonky seams or seams with gaps.
Clone Stamp Tool
The Spot Healing Brush doesn’t always do the job, particularly if you’re trying to use it in an area with a lot of detail. It can introduce brush strokes that look blurry, or perhaps even repair the spot with the wrong texture. In these cases, it’s often best to use the Clone Stamp Tool (the rubber stamp icon).
As the name suggests, the Clone Stamp allows you to clone another area of the photo. It lacks the Spot Healing Brush’s capacity to match the color and texture of the surrounding area, but makes up for this by allowing you to choose the exact clone source.
Return to your photo and view it at 100 percent. Choose the Clone Stamp from the tool panel. As with the Spot Healing Brush, you’ll need to choose an appropriate size for the brush before you continue. Control-click the canvas to call up the brush options and choose a brush size that is just slightly larger than the spot you want to repair. You’ll also want to keep the hardness to 0 percent—this means that the brush will have feathered edges, making it blend better with the surrounding image. Press the Return key to continue.
Now you’ll need to choose the clone source. In order to match the color, texture, and luminosity of the area you’re repairing, look for a spot very close to the area that needs touching-up. Once you’ve found the right spot, Option-click the canvas to lock down the clone source. Move the brush to the area you want to repair, and then click (or click and drag) to tidy up your photo. Notice that once you’ve clicked the canvas to apply a stroke, the clone source then moves in tandem with the brush movement. A second cursor appears as you drag, showing you exactly what’s being cloned.
A major disadvantage of both the Spot Healing Brush and the Clone Stamp Tool is that you need to individually remove every speck of dust and every tiny fiber. The Patch Tool operates like a combination of those two tools, allowing you to tackle a much larger area all at once.
Once again, return to your photo and view it at 100 percent. Choose the Patch Tool from the tool panel and then find an area of the photo you want to repair. If you’ve used the Healing Brush, you may have to click and hold for the tool bar’s flyout menu to reveal the Patch Tool (which has a patch icon). Now, click and drag the tool to create a selection around the dust and other debris you want to remove. The catch here is that you will need an equally large area of the image to use as a texture reference, so be sure to keep your selection a manageable size.
When you’re ready, click in the middle of the selection and drag the cursor away from it. As you do, you’ll notice that you now have two selections. Inside the original selection, you’ll see a dynamic preview of whatever part of the image you’re currently dragging. Position the second selection over the area of the image you want to use as the patch source, and then let go of the mouse button. The original selection will then adopt the texture of the target selection, repairing that area of your photo.
You might want to try a two-step approach if the object in your photo is particularly dusty. Use the Spot Healing Brush first to repair a part of the object, and then use the Patch Tool to repair other areas of the object, using the area you repaired as a patch source.
The Patch Tool is also rather good at repairing or rebuilding seams, so long as you can find another seam to reference. Experimentation is important—if things don’t go as planned, use Photoshop’s History feature to back up and try again.
Dust & Scratches filter
One last way to approach dust cleanup is with the Dust & Scratches filter. This lets you attack a large area of your photo at once, similar to the Patch Tool. However, the filter works by looking for irregularities in a selection (dust specks or thin scratches), rather than simply replacing the entire texture.
Unfortunately, Dust & Scratches generally should not be applied to a whole image; doing so muddies areas of fine detail. To use this filter effectively, you need to make selections. Choose the Lasso Tool and in the tool options across the top of the window, you should see Feather and Anti-alias. Feathering should be set to less than 5 (try 0 to start), and be sure Anti-alias is selected.
Now make a selection around a dusty spot in your photo and choose Filter > Noise > Dust & Scratches. The Dust & Scratches settings window should show you a 100 percent preview of the area you want to clean up (if not, check Preview). Keep an eye on this preview as you tweak the numbers for Radius and Threshold.
Start with a Radius of 10 pixels and a Threshold of 5 levels. The Radius tells the filter how far to apply the cleanup from the point of origin, and in general, you should be good with 10. More important is Threshold. A threshold that is too low will cause blurring of the entire area, so be careful to position the threshold slider at the point where the dust or scratches disappear in the preview. Click OK to continue; if you’re happy with the result, move on to the next problem spot.
All together now
The best way to breeze through such cleanups is by combining all these techniques. Once you’ve repaired edges, seams, and areas of smaller details with the Spot Healing Brush and Clone Stamp, you can move on to larger, more uniform areas using the Patch Tool and Dust & Scratches filter.
It’s still important to carefully dust toys and other objects before you start snapping close-up shots, but with these handy techniques, you’ll be able to clean up unwelcome debris and scratches in short order.