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Dust, Mold, and Texture Removal in Photoshop

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This chapter is from the book
In this sample chapter you'll face the worst problems and learn the best techniques to rescue your images from the evils that lurk in historical negatives, glass plates, prints, contemporary film, and digital images.

Cleanliness is next to godliness, and without starting a religious debate, I am sure you agree with me that the bane of all retouchers is dust, mold, moiré patterns, print texture, and film grain. Removing these problems can be a time-consuming, eye-straining, arm-numbing endeavor, all of which can really take the fun out of digital retouching. In this chapter you'll face the worst problems and learn the best techniques to rescue your images from the evils that lurk in historical negatives, glass plates, prints, contemporary film, and digital images.

The problems tackled in this chapter include

  • Removing dust, mold, and scratches

  • Minimizing moiré patterns and paper texture

  • Reducing, maintaining, and matching film grain

The tools used to conquer these dusty and dirty challenges include

  • Layers and Blending Modes

  • The Clone Stamp tool

  • The Blur tool

  • Photoshop filters

  • The History palette and History Brush tool

So roll up your mousing sleeve and let's get to work.

Depending on the severity of the problem, there are numerous Photoshop techniques to clean up dust and mold, many of which can be used interchangeably or in combination with one another. My favorite technique is to avoid the problem in the first place by cleaning the negative, print, or scanner before making the scan. By carefully brushing or blowing off loose dust from a negative or print, you're removing the source of the problem. Never rub film, prints, or scanner platens very hard because you can scratch and permanently damage them.

Because there isn't one perfect method to remove dust specks or to reduce mold damage, this chapter includes a variety of methods to tackle these problems. Dust problems are most often seen as very small specs of dark or light pixels, and mold damage looks mottled, patterned, or discolored and affects larger areas. By experimenting with or combining methods, you'll develop techniques to take care of your image's worst problems.

Dustbusting 101

An important concept to recognize is that there is no dust in a digital file. The dust was on or in the original. In the digital file all you really have is lighter or darker pixels in contrast to darker or lighter backgrounds. Taking advantage of this concept can speed up your dustbusting sessions.

Using the Blur Tool

The Blur tool is especially useful on files that have a lot of small, random dust specks on a variety of backgrounds. Over the years dust became embedded in the original image shown in Figure 5.1. After scanning, the myriad of small, dark specks makes the wall and the image look dirty and unattractive. The Blur tool was used successfully to clean up the image, as seen in Figure 5.2.

Figure 5.1Figure 5.1 Before


 

Figure 5.2Figure 5.2 After


ch_5dust01.jpg

  1. Add a new layer to the file.

  2. Activate the Blur tool and set its options to 100% Pressure and Use All Layers as seen in Figure 5.3. To eradicate light specks, set the Blur tool's Blending Mode to Darken; to make dark specks disappear, set the Blending Mode to Lighten.

  3. Figure 5.3Figure 5.3 Set the Blur tool to 100% Pressure and Lighten Mode to remove dark specks.


  4. Zoom in to 100% or 200% view.

  5. Set the Blur tool's size to approximately match the size of the dust speck.

  6. Click and hold the Blur tool over the dust spot (see Figure 5.4). The longer you hold down the mouse button, the more the dust will be blurred into oblivion.

  7. Figure 5.4Figure 5.4 Hold down the Blur tool over the speck until it disappears.


NOTE

Be careful not to overblur the dust because that will soften the image area so much that soft blobs will begin to appear. There is a fine balance between just right and too much blurring—with a bit of practice you'll develop an eye for the right amount of blurring.

TIP

Matching the size of the brush to the size of the dust speck to be removed and using a hard-edged brush ensures that you don't soften the grain of the image surrounding the dust speck. Use the keyboard shortcuts to control the size of the brushes:

Left bracket ([) decreases brush size.

Right bracket (]) increases brush size.

Using the Shift key with either bracket adjusts the brush hardness in 25% increments.

The Float and Move Technique

Use the float and move technique on unimportant image areas such as skies or backgrounds to quickly disguise dust on large surfaces. Duplicating a troublesome area with a slight offset and applying a Lighten Blending Mode is a quick and easy way to remove many flaws. I first heard about this technique from Stephen Johnson as he was retouching numerous glass plate negatives for his book, "The Great Central Valley."

Figure 5.5 and Figure 5.6 show before and after detail of the identical file that was cleaned up with the float and move technique. Notice how the dust and mold has been minimized in the sidewalk and the sky. (Because I didn't float and move any important image areas such as the buildings or people, they still have dust and damage that will require individual attention later in the retouching process.)

Figure 5.5Figure 5.5 Before


 

Figure 5.6Figure 5.6 After


ch5dust02.jpg

  1. Select the Lasso tool and set the Feather to 2–5 pixels. The amount of feather depends on your file size—a 10MB file needs a larger feather than a 1MB file.

  2. Make a very rough, irregular selection around the dusty areas, as seen in Figure 5.7. Our eyes more easily detect a straight line, so the ragged edges disguise your retouching better.

  3. Figure 5.7Figure 5.7 Roughly selecting the dusty area helps hide any obvious edges in the sky after retouching.


  4. Transfer this selection onto a new layer by selecting Layer > New > Layer via Copy (Cmd + J)[Ctrl + J].

  5. Press V to select the Move tool and use the arrow keys to nudge the new layer down and over to the right 2–3 pixels.

  6. Change the moved layer's Blending Mode to Lighten to hide the dark spots (see Figure 5.8).

  7. Figure 5.8Figure 5.8 After moving the new layer, change the Blending Mode to Lighten to hide dust and mold.


A Professional Float and Move Example

Photographer John Warner used the float and move technique to repair the lawn of a croquet field which had been aerated to promote lawn growth. John needed to photograph the playing surface for a promotional brochure before the grass had a chance to recover, as shown in Figure 5.9, so he used Photoshop to repair the lawn faster than Mother Nature could have (see Figure 5.10).

Figure 5.9Figure 5.9 Before


 

Figure 5.10Figure 5.10 After


  1. John duplicated the Background layer and set the Blending Mode to Darken, then named the layer Lawn Care.

  2. He used the Move tool and the arrow keys to move the Darken layer several pixels down until the white holes disappeared.

  3. Duplicating and moving the entire layer also affected the cottages. To bring the cottages back into focus, John added a layer mask by clicking the Add Layer Mask icon on the Layers palette.

  4. He used the Gradient tool to draw a black-to-white blend on the layer mask to block the Darken Blending Mode from affecting the cottages and upper part of the lawn, as seen in Figure 5.11.

  5. Figure 5.11Figure 5.11 A gradient will hide areas that you don't want affected with a layer mask.


  6. Finally, John cloned over any remaining white marks on the croquet lawn to add the final polish to the image.

Controlling the Dust & Scratches Filter

The float and move technique works very well on unimportant image areas, such as sky and studio backgrounds. As good as this technique is, it may also soften important image texture or film grain. Use the following Dust & Scratches filter technique whenever you need to maintain texture or film grain.

Figure 5.12 and Figure 5.13 show a before and after detail of the identical file that was cleaned up with this Dust & Scratches filter technique. Notice how the numerous dust specks and most of the mold has been removed from the sidewalk although the film grain and sidewalk texture is still visible.

Figure 5.12Figure 5.12 Before


 

Figure 5.13Figure 5.13 After


ch5dust02.jpg

  1. Select the Lasso tool and set the Feather to 2–5 pixels. The amount of feather depends on your file size—a 10MB file needs a larger feather than a 1MB file.

  2. Make a very rough, irregular selection around the dusty areas, as seen in Figure 5.14.

  3. Figure 5.14Figure 5.14 Roughly selecting the dusty area helps hide any obvious edges in the sidewalk after removing the dust and mold.


  4. Transfer this selection onto a new layer by selecting Layer > New > Layer via Copy (Cmd + J)[Ctrl + J].

  5. Select Filter > Noise > Dust & Scratches. Move the Radius setting up until the dust is obliterated, as seen in Figure 5.15.

  6. Figure 5.15Figure 5.15 Adjust the Dust & Scratches filter filter to remove the flaws in the duplicated layer.


  7. Increase the Threshold value of the Dust & Scratches filter so that the texture is maintained while the dust remains hidden, as seen in Figure 5.16.

  8. Figure 5.16Figure 5.16 Increasing the threshold allows you to maintain texture while hiding the dust and the majority of the mold.


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