Dead pixels only apply to LCD monitors and are easy to detect.
An image editing application works best in full screen mode. Display an image which is a solid light grey and look for individual dark pixels. If you use a very bright white, some dead pixels may not be noticed.
You will also want to check for STUCK pixels. These can be detected with a dark grey or black solid image. They mey be stuck in red, green, blue or in combinations of these colors.