Diminished intensity defects occur in electrostatic printing between image
regions having grey levels, i.e., different electrostatic potential and
toner densities. Such defects occur when higher density regions "steal"
toner from lower density regions. The system and methods according to
this invention compensate for these defects by modifying the input image
data. The input image data in lighter regions that precede or occur near
a light-to-dark transition to a dark region are raised above the input
image values. Thus, when printed, the printed image intensity values in
such regions are higher than the corresponding image intensity values. As
a result, when the higher density regions steal the extra toner provided
due to the raised values, the gray level of the printed image corresponds
to the desired gray level. The magnitude of these defects is periodically
measured with a calibration pattern to generate and/or update
compensation factors used in the compensation process.