Formalization
The reduction of a complex reference to its essential forms, adapted to the constraints of the medium.
In practice
Formalization reduces a complex subject to essential forms that a particular medium can carry, and the medium's limits drive the simplification. A portrait cross-stitched on a 20 by 20 grid must become a few blocks of color; a landscape for a one-color screen print must become flat shapes without shading. The designer decides which features survive the translation and which give way.
Often confused with Abstraction
Formalization simplifies to fit a medium's constraints; abstraction simplifies toward essential shape whatever the medium.
Try this
Redraw a photo of a face on a ten by ten grid of squares using only three colors.