After a time, your photos may contain dead or stuck pixels that are signs of a faulty image sensor. They appear in the same places in all the pictures, under any circumstances (even with the shortest exposure time), usually as sharply luminescent or pitch black pixels. They should not be confused with so-called hot pixels that appear in great numbers when using very long exposure times, and their number increases with exposure time. This is a side effect of the CCD’s amplification and is not experienced under typical circumstances. On the other hand, dead and stuck pixels are dysfunctional pixels and are considered as errors. Now we’ll learn a simple procedure for removing faulty pixels.
Find the bad pixel in the photo. Dead and stuck pixels typically do not appear in large numbers, although they may slowly multiply over time. Most of the time, however, it is a single pixel or a group of few pixels that you can notice in all your photos. If you are unsure of the location, take a photo of a light and a dark smooth surface, both with a short exposure time, to make it more prominent.
In this example, the faulty group is about 2×2 pixels in size.
Zoom the photo to at least 500-600% (by using the Navigator panel on the upper right) to make working with this tiny area easier.
Choose the Rectangular Marquee Tool from the Tools palette (or press M). Select the faulty pixel and an area of at least 1-2 pixels around it. Stuck pixels are often surrounded by a colored border. Make sure to include it in the selection.
Click Filter/Noise/Dust&Scratches in the menu. As the name shows, this filter is primarily used to remove the dust and scratches left on the pictures after scanning analog photos, but can also be used to remove any disturbing picture elements. Of course, if you select an area, the filter will only affect it instead of the whole picture.
On the appearing dialog, set Radius to a value of 1-3, and leave Threshold at 0. If you find the effect too drastic-e.g., if the faulty pixel is not in front of a smooth background, as in this example, but a more detailed object, and the filter also removed details inside the selection-, increase Threshold to refine the result.
As the faulty pixel appears in the same place in all the photos, you can automate the procedure by using Photoshop’s Action feature. This way, you can save the steps for removing the bad pixel and carry them out on all photos.
You can also process a batch of multiple photos: the application can run the procedure even on a whole folder of images, and you’ll have no more trouble with the notorious pixel.
If you are not yet experienced with actions and batch processing, stay tuned. Soon you can find tips on these topics, too!