Function cannyPreviewUbyte

8-bit preview variant that avoids float input conversion.

raster.parallel_rows.ParallelRowsResult cannyPreviewUbyte(
  scope const(ubyte)[] src,
  ulong w,
  ulong h,
  float threshold,
  ref ubyte[] edges,
  ulong workers = 0LU,
  ulong chunk = 1LU
) @trusted;