Geometric Compensation
Artwork files are modified during the design phase to account for the physical distortion that happens during the printing and converting processes. Prepress inverse scaling involves shrinking or stretching the design in one direction to counteract the known expansion or contraction of the substrate. This is particularly common in flexographic printing where the rubber plate stretches as it is wrapped around a cylinder.
By starting with a distorted image, the final print on the board appears at the correct size.
Distortion Prediction
Calculating the correct amount of scaling requires knowledge of the cylinder diameter and the thickness of the printing plate. If the math is wrong, the images will look squashed or elongated on the finished package. In the case of paperboard, inverse scaling might also be used to compensate for the way a sheet grows when it absorbs moisture from the ink.
This ensures that barcodes and other technical elements remain within the scanable tolerances.
Finished Accuracy
High quality graphics depend on every element of the design lining up perfectly. When multiple colors are printed, each plate must have the same scaling applied to maintain registration. Modern prepress software automates this process by applying a percentage factor to the entire job.
This prevents the need for manual adjustments and reduces the risk of human error in the design department.
