pub const EDGE: u8 = 8;Expand description
A PNG’s or JPEG’s pixels, straight RGBA.
How far apart two drawings of the same scene may be. Two rasterizers of one
display list differ only in how they anti-alias an edge: a pixel on an edge
takes some value between the colors either side of it, and each rasterizer
picks a slightly different one. So a pixel is unexplained when, in some
channel, its value lies more than EDGE outside the range of the other
drawing’s pixels around it (itself and its eight neighbours), in either
direction. A missing or moved part — a divider, an icon, a word — leaves
pixels no neighbour in the other drawing explains. At most SHARE of the
pixels may be unexplained, and no 8-connected cluster of them may be larger
than CLUSTER.