Quantitative cytology requires accurate representation of a specimen's optical densities. As the requirements for measurement precision increase, instrument-induced errors become increasingly more difficult to reduce to the point at which their effect on experimental data is insignificant compared to the measured parameters. Shading induces a significant amount of amplitude ambiguity to data obtained from a scanning system. A method of shading correction on single pixels is introduced as a new way to reduce some errors that currently plague scanning systems.