Robert's Cross edge detection jit.robcross implements the Robert's Cross method of edge detection. Cycling '74 Jitter Jitter Blur/Sharpen in TEXT_HERE TEXT_HERE out TEXT_HERE dumpout TEXT_HERE char long float32 float64 Edge detection threshold Edge detection threshold (default 0.). Cell values below this threshold are set to 0. This particular edge detector uses a 2x2 convolution kernel to compute a 2-dimensional spatial gradient of an incoming matrix, brightening features with "high spatial frequency" -- a large amount of change from cell to cell -- and darkening features with less change.