The quality of the scanner that captures and digitizes the image affects the output. Scanners use different input technologies:

CCD - Charged-coupled device

CCD scanners also known as flatbed scanners, have an array of photosensitive diodes. When light hits the array, the diodes give off charges equal to the levels of light. The light is digitized and the diodes' output value becomes part of the image area.

PMT - Photomultiplier Tube

PMT scanners, also known as drum scanners, are like television tubes in reverse. A television tube emits light when charged, while a drum scanner emits an electric charge when light hits it. The photomultiplier tube sends the charge to a converter that changes the energy into digital data.