This page features a rudimentary lattice detector.
This only detects true lattices of either square (Green Lattice, Red Lattice, etc.)
or hexagonal (RGB Lattice, Neon Lattice, etc.) form,
including, optionally, ones which have the same colors adjacent (but separated by the lattice mesh - e.g. some incarnations of Rainbow Lattice)
as well as checkerboards - which will result in lots of false positives from dithered colors.
Other repeating patterns - while often referred to as lattices, such as Cell, Spurdo, etc. - are not recognized.
Checkerboards / checkerboard dithering
Allow same adjacent colors in lattices