Removing Dust & Defects
Key Concepts
Cloning
The way retouching has been done from the very early versions of Photoshop is by “cloning” pixels from one part of an image and using them to obscure blemishes we don’t want. The mechanism is a tool that uses a brush metaphor, called the Clone Stamp Tool in Photoshop, or Spot Removal in Lightroom and ACR. Quite simply, it is like very quickly selecting an area, copying it, then pasting it elsewhere. In nondestructive workflows, including those involving Smart Objects, the cloned pixels go onto their own layer above our source image.
Healing
An advancement over cloning, the healing function uses the same painting procedure as cloning—but rather than only making identical copies, it then blends them into the new area by pulling color and luminosity from the surrounding pixels. In a way, healing copies texture only, drawing on the context where it’s placed to determine color and tone.
In Photoshop, there are three tools that can “heal”: the Spot Healing Brush, the Healing Brush (my favorite), and the Patch Tool (which is layer-specific, sadly). The Spot Removal Tool of ACR and Lightroom can be set to either clone or heal.
Sampling, Sources, & Alignment
All of these tools pull data from elsewhere in the image (in Photoshop, we can pull from other images, too). The Spot Healing Brush chooses its source automatically, and the Spot Removal Tool can also do so. The Clone Stamp tends to use a source that is relative in position to where you apply it (40 pixels above and 90 pixels to the right, for example). We say it is aligned.
The Healing Brush Tool tends to pull data from the same source again and again because it can: it contextualizes the data to blend into its new surroundings. We say that it is not aligned.
Content Awareness
Content Awareness (CA) is a feature that several tools in Photoshop can use. The Fill command, the Spot Healing Brush, the Patch Tool, and (surprise) the Content-Aware Move Tool can automatically fill a designated area of an image with semi-random content from elsewhere in the image. Content Awareness sometimes does odd and humorous things, but most often it astonishes.
Procedures
Spot Removal Tool
The Spot Removal Tool is at the upper left in Adobe Camera Raw or just below the histogram in Lightroom. The differences beyond that are mostly cosmetic.
How to use the Spot Removal Tool:
- Line up the cursor on the center of the flaw you wish to remove. Click to create a circular repair target. Drag (paint) to create an arbitrarily shaped target area. ⌘+option/Ctrl+Alt dragging resizes the brush and creates a circular spot.
- If necessary, resize overlays afterward by dragging their edges.
- The application will automatically choose a source for the repair. Tap the / (forward slash) to have the application offer another choice. You may choose your own source by dragging the source to any location in the image. To do so at the outset, hold ⌘/Ctrl and drag from your target to a desired source, creating a circular spot.
- To delete a Spot Removal repair (spot removal removal?), select it with the Spot Removal Tool, then tap your delete/backspace key. option/Alt dragging a marquee removes all spots inside the marquee.
- To toggle the visibility of the overlays, tap V in ACR or H in Lightroom.
Removing spots caused by sensor dust can be tedious if they appear on many images. You may select multiple images and enable Auto Sync to have each click clean up dust on many images at once.
Photoshop
Vital Preliminaries
In Photoshop, we employ three essential tools for spot removal: the Healing Brush, the Spot Healing Brush, and the Clone Stamp. These work by sampling “clean” pixels and using them to repair or replace defective pixels. As you may make a mistake or change your mind, I recommend creating a separate layer just above the original image to hold your retouching in case it needs to be revisited. It seems more difficult at first, but saves much woe later.
Note that I put this new layer between my original image’s layer or Smart Object and any adjustment layers I may have. Just create the retouching layer, then move it if it’s in the wrong place.
You must configure each of the retouching tools to pull the “clean” pixels from the layer(s) below. So for each tool, note the item in the Options Bar labeled Sample. Choose to use material from the original and your repairs. Since this layer is below any adjustment layers, it is affected by those adjustments exactly as the original is. If we chose to use All Layers, we could risk putting adjusted pixels where they’ll get adjusted again. If this sounds confusing, that’s because it is. But it will make more sense the more you use these tools. You will note that the Spot Healing Brush has only a checkbox labeled “Sample All Layers.” It is safe to use this, as this tool is smart enough to do the right thing automatically.
Summary: For each retouching tool, use the item in the Options Bar labeled “Sample” to choose for sampling data from the original image plus your repairs while wisely working on a separate retouching layer. Check the “Sample All Layers” box for the Spot Healing Brush Tool.
Larger defects are repaired by using Content-Aware Fill (CAF), the Patch Tool, or the Content-Aware Move Tool. Sadly, CAF cannot sample other layers. The Patch Tool can in its new CA mode, but not in its Normal (healing) mode. So if we wish to use CAF or the awesome healing Patch Tool nondestructively, we need to duplicate our original layer. If that original is a Smart Object, we then rasterize the duplicate by choosing (see the illustration above). I usually mask or delete the excess pixels on this layer when I’m done Patching or Filling.
Removing Small Defects
Clone Stamp Tool
In Photoshop, it is rare to use the traditional Copy and Paste functions. One reason is that when you copy something, it can be many megabytes of material that clogs your computer’s memory. There are more useful and elegant ways of copying material.
Use the Clone Stamp to copy a piece of an image and “stamp” it onto another area of the image. This tool cleverly uses a painting metaphor: larger brushes copy more pixels, and softer brushes blend the copied pixels into their new surroundings. You can even alter the opacity of the brush to make the clone only partial. Use the same shortcuts you would use with the Brush Tool to change brush attributes.
- Zoom in. makes it easier to see dust spots and defects you might otherwise miss. Periodically hold the H key to access the Hand Tool. Use this to move along to new areas to retouch. Release the H key to resume retouching. If you are startled by the “Bird’s Eye View” zooming effect, you may use the spacebar instead. It also accesses the Hand Tool without the zooming.
- Find a flaw in the image and note an adjacent area without a blemish but with a similar texture, color, and density. You’ll clone from this clean area onto the blemish or spot. If the flaw is along an edge, choose a point further along the same edge (as in the example above).
- If the defect is small like a dust speck, select a brush slightly larger than the defect. Otherwise, a brush of between 20 and 100 pixels will be fine.
- Place the cursor over the clean area of the image. It appears as a circle the same size as the selected brush. Hold down option/Alt to display a small target, then click on the clean area to designate it as the source. Important: Once you designate the clean area as your Clone Source, release option/Alt.
- Move the cursor over the spot to be removed. Notice how the cursor displays the material that you will be painting shortly. If you have an adjustment layer above the retouch layer, the material may look discolored, but it will paint correctly if, in the Options Bar, you choose to sample Current [layer] and Below.
- Paint over the spot. You will see two cursors while you paint: the center of your source marked with a + cursor, and the circle of your brush. There is a spatial relationship between them that will be maintained until you define a new source point. So, if you define a source above and to the right of where you paint, when you paint elsewhere in the image, the source will be above and to the left of the cursor in its new location. The trick is to keep an eye on each cursor to be sure that as you paint, your source doesn’t drift toward areas inappropriate to cover your blemishes. The difficulty is that the source cursor is visible only while you paint. Use your inner eye, I suppose.
- Repeat for each defect. Remember that you need to set a source point only when the alignment between source and brush no longer serves.
I strongly suggest that for larger defects, and for areas with many defects, you change your source point alignment frequently to avoid noticeable repeats of a pattern.
Healing Brush
The Healing Brush Tool is very similar to the Clone Stamp in that you specify a source point by option/Alt clicking, then paint away defects. It also loads the cursor with the sampled material. But there is a huge difference.
When you paint over a defect, you must paint it completely gone in one brush stroke. While you do so, you may think you chose the wrong source—what you’re painting may look a bit dark or light. But when you release the mouse, Photoshop does its magic: it uses the texture of the source pixels, but then uses the color and density surrounding the flaw, or more precisely, where you painted. So there had better be no flaw left. Even if your source pixels are very different in color and density from the flawed area, but have a similar texture, the resulting repair will be seamless. Essentially, you define a texture to use, then fix areas with the same texture (sky texture for defects in a sky, or stone texture for defects in stone, etc.).
In short, you control the source texture, and Photoshop sweats the other details. Use the Clone Stamp when you need a literal copy of pixels. Use the Healing Brushes when a copy is the wrong color, density, or both.
Sometimes the Healing Brush fails and creates an obnoxious smudge. This is common if the dust spot is right along a strong edge, or especially if the flaw is in a corner of the image. If this happens, press ⌘+Z/Ctrl+Z. If the flaw is in a corner, first use the Clone Stamp, then Heal. For flaws along edges, use a source point further along the same edge.
Spot Healing Brush
The Spot Healing Brush is an alternate version of the Healing Brush. It works by merely painting on a dust spot or defect in the image without first defining a source.
Click or paint on the defect, and Photoshop eliminates it—usually. It picks its own source material. If it chooses inappropriately, use the Healing Brush or Clone Stamp.
The Spot Healing Brush has several options. But I keep the Mode set to Normal and the Type set to Content-Aware.
The Spot Healing Brush works best with a hard-edged brush—a soft-edged brush doesn’t completely fix a defect. If you should accidentally soften the brush, Right-click anywhere on the image to increase the brush’s hardness.
Save the Clean Image
After you have completed the image cleanup, use . If the file is a RAW image, you may be presented with the Save As dialog, as Photoshop edits cannot be saved directly into RAW files. JPEGs cannot hold Layers, so Photoshop will give a Save As dialog for them, too.
Remember to change the label, so you know that the file has been cleaned and whether it needs more work.
Larger Defects
It can be tedious to repair large image areas. But a few tools can make a great start or even complete the job in a few clicks if we’re lucky. However, to do this reversibly, as you know I recommend, we have to do a little more setup.
Setup Note: Some of the following methods don’t sample any layer but the active one. So, to work on an extra layer while preserving your original:
- Duplicate your original layer or Smart Object:
- If you now have two Smart Objects, you’ll have to rasterize the duplicate: ..
Or, if you've already created other layers, including adjustments, that you would like to play an active role in fixing more of the image, you may follow these steps instead:
- Create a new, empty layer via and give it a reasonable name.
- Merge a copy of the image into this new layer by using the shortcut ⌘+option+shift+E/Ctrl+Alt+Shift+E. This merges a copy of everything you see into this one layer, preserving the others—just in case.
That’s it. Now we can safely proceed—or reverse if we really make a mess.
Content-Aware Fill
To convincingly remove large areas quickly had always been somewhat difficult. Today, we can simply select an area, fill it with “content awareness,” and Photoshop will find bits and pieces of the image to fill in that selection.
- (Re)read the setup note on the previous page above.
- Make a slightly loose selection around the flaw with any selection tool.
- Choose In the Fill dialog box, choose .
- Click OK, then retrieve your jaw from the floor.
Patch Tool
The Patch Tool is like a custom-shaped, extremely large Healing Brush. Rather than painting, we use selections to indicate what should be fixed—or with what to fix our flaws. Unfortunately, only the Patch Tool’s new Content-Aware mode works on empty layers by sampling below. If we wish to use its healing power, we must work directly on standard image pixels.
To patch:
- (Re)read the setup note on page 233 at the beginning of this section.
- Make a slightly loose selection around the flaw with any selection tool, including the Patch Tool itself.
- Now the cool part: With the Patch Tool, drag the selection to an area you would like to use as your patch (the repair); that is, good pixels that can be used for their texture and detail. If you’re using Normal mode, don’t worry about color or lightness as there will be a healing calculation when you release the mouse. In Content-Aware mode, you may use this tool on another layer and adjust the Structure and Color amounts until you have the right fidelity to the patch material (from Structure) and color of its new surroundings (Color amount).
- Release the mouse and deselect. Nice.
Content-Aware Move Tool
So far, I have not found this tool impressive. A combination of Patch and CAF, it is not as powerful as those two used sequentially. However, it seems to do well with smaller items surrounded by nondescript imagery.
Transformations
Bending images is both fun and practical, if more extreme than removing dust. Let’s look at a couple of ways to get images to fit your visualization.
Free Transform
Free Transform scales (and skews, etc.) all the pixels that are selected. However, you have a few modes to choose from. The standard transform is rectilinear and wholesale.
Choose or use the keyboard shortcut ⌘+T/Ctrl+T. Once in the interface (a box with handles on the edges), you may drag a corner or edge. If you have a specific amount of distortion in mind, you may enter it in the fields in the Options Bar. You may also set the interpolation method used when you scale. Use the Enter key to commit the transformation.
You may also engage Warp mode to get a more fluid transformation. Choose Warp mode with the button that appears on the right side of the Options Bar when Free Transform is active. You may choose a preset Warp like Flag (left), or create your own via Custom. With the Custom interface, you may drag on the grid or the “handles” along the edge to sculpt the selected pixels in fluid and natural ways.
Liquify Filter
For a painterly distortion, use the Liquify Filter. Access it by and choose a tool in the upper left. Adjust the characteristics of the tool, always brush-like, on the right side of the interface.
But the fun is had in the middle. Paint with the Warp Tool, and you sculpt pixels. Use the Pucker or Bloat Tools, and you can see why this filter is used extensively in fashion and catalog photography. Advanced mode yields many more options.
Liquify can now be applied to Smart Objects, so be sure you convert your image layer(s) to one if it isn’t already.
- Choose . Use tools like Warp, Pucker, and Bloat to “sculpt” the image. Use the Reconstruct Tool to paint the image back to its original form.
- Check the box for Advanced mode. You may use the Freeze Mask Tool to protect parts of the image from further disruption. Thaw Mask makes them vulnerable again.
- Have fun.
Content-Aware Scaling (CAS)
CAS is like Free Transform, but treats your content with respect. However, it cannot be used on either Smart Objects nor backgrounds. Create a rasterized duplicate layer if you wish to use this feature.
You may choose or use ⌘+option+shift+C/
Ctrl+Alt+Shift+C to engage this function. What you’ll notice when you drag an edge or corner is that areas with fine detail distort far less than areas that are more homogeneous.
Even more powerful is the combination of this tool with a saved selection. If you first create a Marquee (perhaps with the Quick Selection Tool), then save that selection, you’ll see the name of that saved selection in the Options Bar under the Protect menu.
- Create a selection around important content, especially if it contains areas without fine detail.
- Choose and give your selection channel a name.
- With a single image layer selected, but not a Smart Object, choose or use ⌘+option+shift+C/Ctrl+Alt+Shift+C.
- In the Options Bar, choose the name of your saved selection from the Protect menu.
- Scale the layer.
For amusement, you should photograph a small automobile and Content-Aware Scale it upward. That is, make it longer. Imagine a Mini as a limousine.
