Nearly all of my old family photos have dust, scratches, and other specks. Even most of the newer ones have little pinhole-sized white specks here and there. Some of my really old ones have hundreds of big specks and dozens of scratches all over. The Dust & Scratches filter in Adobe® Photoshop® Elements works well on these.
While you can use the Dust & Scratches filter on the entire image at once, some images turn out better when different strengths of the filter are used selectively on different areas of the photo. For example: You have on an old photo covered in thousands of specks. You might want to use a low radius and high threshold for foreground objects such as people so you don't remove fine facial details, and use a high radius and low threshold for background vegetation where detail loss may be less noticeable.
You can also use the Dust & Scratches filter to remove coarse noise that a noise filter was not able to remove. For example: You have a flash photo of some people standing in front of a wall. There's a little noise on the faces and lots of coarse noise on the wall. A noise filter is used on the entire image which removes the noise on the face but leaves the stubborn coarse noise on the wall. The Dust & Scratches filter can then be selectively used on the wall to soften the coarse noise.
When using the Dust & Scratches filter, please be careful of areas with a lot of fine contrasty detail. This includes eyes, teeth, eyeglasses, coarse fabric (tweed), small patterns (tiny stripes/boxes), lettering, belt buckles, and brilliant bling (rings/jewelry).
Every time you use the Dust & Scratches filter, I suggest checking the image to make sure that details are not smeared. Checking the image can be done within the filter or using Undo & Redo after applying the filter. Once you find settings that preserve as much detail as possible while removing most of the dust, you're done. Pretty simple, in theory.
Dust & Scratches Filter
There's a three-step process to determine the correct settings for using Photoshop® Dust & Scratches.
First, start by setting Threshold to 0.
Second, adjust the Radius to match the size of the dust (aka dots, scratches, spots, or specks). You can start with 2 and use the preview within the Dust & Scratches filter dialog box to check the result. If the dust is not removed, raise the Radius by one until the dust just disappears.
Third, set Threshold to 5. If enough fine details return so that the image looks good with plenty of detail and no smearing, you are done. If not start raising Threshold and checking fine details in the image each time you raise Threshold until the image looks good. For dark or blurry images with little detail, I would raise Threshold by 1 each time. For images with lots of fine detail, I would raise Threshold by 5 each time. This is because images with lots of detail will require a high Threshold to retain that detail, and you will save time by raising it by 5 instead of 1.
In all my examples below, I have determined the correct values by using the above instructions. For the first example below called "Tiny Dots Example", I started with a Radius of 1. I raised it by 1 until I found that almost all the tiny dots were removed at a value of 2. I then set Threshold to 5. Because there was so much detail in this newer photo, I raised Threshold by 5 until I found that virtually all the detail (except for the eyes and teeth) was retained at a value of 20.
Here are some sample settings. You can start with these settings and make adjustments as needed.
||Radius = 1
||Radius = 2
|medium dots (specks, scratches)
||Radius = 3
|large dots (spots)
||Radius = 4
|blurry photo, dark shadow
||Threshold = 5 to 10
||Threshold = 10 to 20
|bright areas w/fine contrasty details
||Threshold = 20
Small Dots Example
I have commonly found hundreds of small dots in newer photos. These dots are very small and bright white. The smallest of these dots are the size of pinholes and can usually be removed using a radius of one with the Dust & Scratches filter. However, a radius of two removes nearly all small dots, including the pinhole-sized dots.
Unfortunately, newer photos have a lot of high contrast detail that is important to keep. To remove small dots without removing detail requires the threshold to be high. For darker areas without much contrasting detail, a threshold of 10 might work. For areas with detail, a threshold of 20 would work better.
The first image is a close-up of a typical newer photo in excellent shape. There are lots of small white dots all over, mostly noticeable in the medium and dark brown objects, and not very noticeable in other objects such as the person in the chair.
The second image shows selective use of the Dust & Scratches filter. I selected brown objects without small contrasting details (table, belt, vinyl chair, paneling). I then used a radius of 2 and a threshold of 10 on the brown objects. I only used this filter on brown objects, as this threshold was not high enough to prevent detail damage to the person in the photo. This selective use of the filter cleaned up the dots nicely in the shadows.
The third image shows less selective use of the Dust & Scratches filter. I selected the entire image except for the Christmas wrapping and the eyes and teeth of the person in the chair. I then used a radius of 2 and a threshold of 20 on the selection (everything but the wrapping and eyes and teeth). This threshold was high enough to prevent detail damage to selected objects. The pinhole-sized dots were removed, but some small dots were not.
Selective use of the filter with dark or brown objects has removed most of the surface damage (dots).
brown objects selected
all but eyes/teeth/wrap selected
Meanwhile, in another part of the same image... If the Christmas wrap had not been de-selected before using the Dust & Scratches filter, the wrap would have turned out like this:
You can see how much damage even a low radius of 2 can do to a photo. Even with a threshold of 10, the white ribbon and orange berries in the second image have become blurry, as shown in the second image. Even using a threshold as high as 20 can cause damage, as shown in the third image. While not as blurry as the second image, there are new blurry white pixels around the edges of the white ribbon.
entire image selected
entire image selected
While using a low radius and high threshold helps reduce detail damage, selective use of the Dust & Scratches filter can be used to avoid areas with high detail completely.
Remove Scratches selectively to avoid adding Dust to details.
Dark shadows are where specks and scratches lurk. In many photos, scratches are quite noticeable in darker areas of the photos, and not very noticeable in bright areas. Selective use of the Dust & Scratches filter works well to remove such scratches.
The first image is a close-up of a murky shadow with lot of small but noticeable specks and scratches.
The second image shows use of a moderate radius (3) in the shadows. I selected the shadow, then used a radius of 3 with a threshold of 5. This cleaned up the specks and scratches very nicely. Because the shadow was so murky and had so little detail, using a moderate radius with a low threshold worked well.
The third image shows use of a light radius (2) in the shadows. I selected the shadow, then used a radius of 2 with a threshold of 5. While this was enough to almost all of the specks and scratches, a few are still visible.
Specks and scratches were a blight in the night, but a low threshold on shadows turned out just right.
Blemishes are quite noticeable on brown vinyl and other types of dark featureless material. Selective use of the Dust & Scratches filter to the rescue!
The first image is a close-up of a dark brown vinyl chair with very noticeable blemishes.
The second image shows selective use of a high radius (4) on the chair. I selected the entire chair (not including the person in the chair), then de-selected the shiny white parts of the chair. This left just the dull brown vinyl selected. I then used a radius of 4 with a threshold of 5 to help hide the scratches. Details would usually be badly smeared with a radius that high, but it turned out fine for the vinyl. Because vinyl is so featureless, using a high radius with a low threshold worked well.
The third image shows less selective use of the same radius and threshold as the second image. The difference is the shiny white parts of the chair were not de-selected before using the Dust & Scratches filter. You can see the white parts of the chair have lost detail. This is because the filter blends the high contrast edges between white and brown.
brown parts of chair selected
entire chair selected
Selecting objects takes time and skill to master, but better and slower beats blurrier and faster.