v3grad − calculates the 3D gradient of an image sequence

v3grad if=infile of=ofile [of1=ofile1] [of2=ofile2] [a=alpha] [-g] [-d] [-vH] [-v]

V3grad is a program that computes three-dimensional gradients using the recursive filtering algorithm of Monga, Deriche, and Rocchisani. When computing a particular gradient, gradient computation is performed in one direction and smoothing is performed in the two orthogonal directions. Zero borders are added to the 3D image to fascilitate the start up of the recursive filters. All computations are performed on a floating point image sequence. Other image formats are automatically converted to floating point and the final result is a floating point 3D image. Typically the output of the algorithm is gradient magntiude and phase information. If the -g option is specified the output will be the x, y, and z gradient data. An important parameter for the approach is alpha (a) which provides a trade off between noise suppession and localization. The paper entitled, "3D Edge Detection Using Recursive Filtering: Application to Scanner Images" by Monga, Deriche, and Rocchisani is published in CVGIP 53:1, pp. 76-87, 1991.

Output files do not maintain file markers (except for the -d option) Also any z index offset may not be maintained.

if=<value>

input 3D image or image sequence.

of=<value>

floating point 3D image which contains the magnitude of the 3D gradient of the input file.

of1=<value>

3D floating point image which specifies phase information associated with the 3D gradient of the input file.

of2=<value>

3D floating point image which specifies phase information associated with the 3D gradient of the input file.

a=<value>

a floating point number which controls the trade off between noise suppression and localizatoin. Typically 1.5 is a good number and is the chosen default.

-g

The -g option specifies the output of the X(ofile), Y(ofile1), and Z(ofile2) gradients opposed to the gradient magnitude and phase information.

-d

The -d option specifies the output is a single three channel file (of1= and of2= are ignored). z-offsets and frame markers are created as for a 3D image.

-vH

The -vH option gives help on command line arguments.

-v

verbose mode

Trina D. Russ