abstract
angle
background
black white
blank
block
box
chaotic
contrast
edge
edgy
geometric
geometry
gradient
gray
grayscale
grey
greyscale
layer
level
minimal
multiple
opart
overlap
overlay
pointed
pointy
quad
quadrangle
random
rectangle
rectangular
rotation
rough
shape
spiral
square
stack
stain
stress
structure
tense
tier
tile
variation