edge

edge, a FORTRAN77 code which defines some test functions in 1D, 2D and 3D for the detection of edges, and uses gnuplot() to display images of the functions.

In particular, we look at some simple functional examples in 1D, 2D, and 3D, that is, situations in which a formula is supplied so that the value of a scalar quantity f() can be determined at any point in the region. We are interested in examples in which the quantity f() exhibits jumps. that is, sudden, sharp changes in value.

Licensing:

The computer code and data files made available on this web page are distributed under the GNU LGPL license.

Languages:

edge is available in a C version and a C++ version and a Fortran90 version and a MATLAB version and an Octave version.

Related Data and Programs:

edge_test

gnuplot_test, a FORTRAN77 code which illustrates how a program can write data and command files so that gnuplot can create plots of the program results.

image_edge, a FORTRAN77 library which demonstrates a simple procedure for edge detection in images.

Reference:

• Rick Archibald, Anne Gelb, Jungho Yoon,
  Polynomial fitting for edge detection in irregularly sampled signals and images,
  SIAM Journal on Numerical Analysis,
  Volume 43, Number 1, 2006, pages 259-279.
• Rick Archibald, Anne Gelb, Jungho Yoon,
  Determining the location of discontinuities in the derivatives of functions,
  Applied Numerical Mathematics,
  Volume 58, 2008, pages 577-592.
• Larry Shepp, Ben Logan,
  The Fourier reconstruction of a head section,
  IEEE Transactions on Nuclear Science,
  Volume NS-21, June 1974, pages 21-43.
• Larry Shepp,
  Computerized tomography and nuclear magnetic resonance,
  Journal of Computer Assisted Tomography,
  Volume 4, Number 1, February 1980, pages 94-107.

Source Code:

• edge.f, the source code.
• edge.sh, BASH commands to compile the source code.

Examples and Tests:

• edge_test.f, calls all the tests.
• edge_test.sh, a BASH script that runs the example.
• edge_test.txt, the output file.