vedgedir − Performs various edge-highlighting operations

vedgedir if=<ifile> of=<ofile> xv=<x-vector> yv=<y-vector> zv=<z-vector> th=<theta> ph=<phi> [-b] [-w] [-hone] [-hall] [-v]

vedgedir highlights edges based on certain criteria. The required input file is the image that needs highlighting (if=). The output (of=) is the image with highlights in type float (unless specified as byte by the -b flag). There are three types of highlighting that can be done: gradient direction highlighting in one direction (specified by [-w]), which shows the the strength of the gradient’s direction in the specified direction; gradient magnitude highlighting in one direction (specified by [-hone]), which highlights the strength of the gradient at a point in the specified direction; and all-directions testing (specified by [-hall]), which finds the direction in which the gradient at a point (A) is strongest and compares the magnitude of the gradient with the two points adjacent to (A) in the same direction. It highlights points that have a higher gradient in the found direction than the two adjacent points.

For [-w] and [-hone]: xv, yv, and zv, specify a vector that gives a direction from each point in which to test for edge strength. Alternatively [th=] and [ph=] specify the direction with th being the angle from positive x-axis in the x-y plane, and ph being the angle from the positive z-axis. For [-hall], no direction needs to be specified.

-b is the flag which instructs vedgedir to convert the output image to type byte rather than float. The lowest negative values in the float image correspond to 0 in the byte image, while the highest positive correspond to 255 in the byte image. 0 in the float image corresponds to 128 in the byte image. -v is the verbose flag.

vedgedir is restricted to usage on images of type float. It can be used on outputs in channeled form from the function v3grad.

if=

input image

of=

output image

xv=

x-component of direction of interest

yv=

y-component of direction of interest

zv=

z-component of direction of interest

th=

angle from positive x-axis on the xy-plane for the direction of interest

ph=

angle from positive z-axis for the direction of interest

-w

highlight strength of gradient (in terms of direction) in specified direction

-hone

highlight strength of gradient (in terms of magnitude) in specified direction

-hall

highlight local maxima in gradients among adjacent points along grad direction

-b

output image in byte format

-v

verbose mode

D. T. Masetti and A. P. Reeves