[OctDev] new imaging functions (graycomatrix, houghtf)

[Stefan v. d. W. <st...@su...>]

I submitted two new functions, "graycomatrix" and "houghtf".  Please
try the demos and let me know if you see gremlins in the code.

Regards
Stefan

usage: P = graycomatrix(I, levels, distances, angles)

  Calculate the gray-level co-occurrence matrix P = f(i,j,d,theta)
  of a gray-level image.

  P is a 4-dimensional matrix (histogram). The value P(i,j,d,theta)
  is the number of times that gray-level j occurs at a distance 'd'
  and at an angle 'theta' from gray-level j.

  'I' is the input image which should contain integers in [0,
  levels-1], where 'levels' indicate the number of gray-levels counted
  (typically 256 for an 8-bit image).  'distances' and 'angles' are
  vectors of the different distances and angles to use.

usage: [H, R]  = houghtf(I[, angles])

  Calculate the straight line Hough transform of an image.

  The image, I, should be a binary image in [0,1].  The angles are
  given in degrees and defaults to -90..90.

  H is the resulting transform, R the radial distances.

  See also: Digital Image Processing by Gonzales & Woods
  (2nd ed., p. 587)