Question

What are empty pixels?

Answer

Empty pixels are pixels that contain no useful data. They are created by excessive magnification of an image. Empty pixels contain no data because neiboring pixels contain the same information.

The total magnification of a traditional desktop microscope is the product of the magnification of the objective (10x-60x) and magnification of the eyepiece (usually 10x). So, a microscope with a 20x objective delivers 200x magnification.

An effect of excessive magnification is that at some point what is known as empty magnification occurs. This happens when the image is magnified but no additional detail is resolved. In digital microscopy, we get what are known as empty pixels. In effect, rather than collecting a green pixel, we collect a 2x2 block of green or (even worse) a 3x3 or 4x4 block of all green pixels. These empty pixels are wasted space because, although the image appears larger, the additional pixels add no additional image resolution.