What are hot pixels?
Hot pixels are a defect found in many digital cameras. They show up during long exposures, especially if you use high ISO settings. They can show up as little white spots, sometimes looking like little specks of dust that accumulate in the darker areas of your image. This is something every night photographer has to address.
Four steps for removing hot pixels
1. Create a new layer
If you are working with an editor that supports layers, create a new layer first. If not, it will still work but you won’t have as much control.
2. Apply Dust & Scratches filter
Your editor likely has a method of removing dust and scratches. Sure, we may not have any of those on our digital image. However, we can also use it for stuck or hot pixels. From the top menu in Photoshop, select Filter > Noise > Dust & Scratches.
This will produce the Dust and Scratches Filter dialog box. Begin with a setting of one or two pixels. Then slide the Threshold slider until it makes most or all of the hot pixels disappear but doesn’t make your image blurry. Press “OK.”
3. Create Layer Mask
In Photoshop, make sure the new layer that you just worked on is selected. Go to the top menu and select Layer > Layer Mask > Hide All. This will produce a black mask in your Layers. You now won’t be able to see your new layer.
4. Paint away the hot pixels
Click on the two squares on the left side. This is the Color Picker. Select the color white from the top box. Then select the Paint Brush from the left side of the menu. Make sure the black Layer Mask (next to the layer you’re working on in the Layers Menu) you just created is selected. Then simply start painting all the areas in which you want the hot pixels to disappear.
If your editor does not work in layers, try the filter anyway!
Some editors have a Dust & Scratches filter or something similar, but do not support layers. That may be OK. Try adjusting the pixel size and threshold anyway. Many times, you can achieve a good result with just this.
I kept this article short and sweet. However, I’ve written a more detailed article about eliminating hot pixels. This illustrates out several ways to address hot pixels.