Techniques ensuring that high quality is maintained through various stages of a process. For example, quality control during image capture might include comparing the scanned image to the original.

The artificial forcing of like gray levels to the same gray level as a result of limited tonal resolution in a scanner. Quantization is most often seen in the shadow portion of scanned images.

Tones between shadow and midtones are known as 3/4 tones and those between highlight and midtones are known as 1/4 tones.