Layout constraints flags (bits 0 to 15). All of those introduce "gap pixels" after the scanline, in order to follow the various constraints.
if you want to process 4x RGBA8 pixels at once, with aligned SSE, use: LAYOUT_MULTIPLICITY_4 | LAYOUT_SCANLINE_ALIGNED_16
See Implementation
Layout constraints flags (bits 0 to 15). All of those introduce "gap pixels" after the scanline, in order to follow the various constraints.