The drawing is incorrect.<p>More specifically, it’s a drawing of OEIS A054521 (black if gcd(row, col) == 1, red otherwise), not of the parallax compressed primes. The two drawings do not match as claimed. The first place where they differ is row 9, column 1, which is drawn as black even though none of 217, 226, 235, 244, 253, 262 are prime.<p>It’s clear that gcd(row, col) == 1 is a necessary condition for there to be any primes in that cell (which consists of the numbers col + 3row² − 3row, col + 3row² − 2row, col + 3row² − row, col + 3row², col + 3row² + row, col + 3row² + 2row), but it’s not sufficient. There’s no way it could be sufficient, because there are only constantly many (six) numbers tested in every cell, but the asymptotic density of the primes goes to 0 and the asymptotic density of A054521 goes to 6/π².