OMNIVIS project 2009

Filters Mathematica

OMNIVIS: Omni-directional Vision

Office: SciCtr 434

Email: knill@math.harvard.edu

## MathematicaMathematica 7 has quite many image manipulation features.A = Import["leman.jpg"]; w=Length[A[[1,1]]]; h=Length[A[[1]]]; B = ColorNegate[ImageMultiply[LaplacianFilter[A, 1], 1]]; Export["leman1.jpg",Show[B],"JPG",ImageSize->{w,h}];What does the Laplacian Filter do? Here is an experiment: (you have to run this in a Mathematica notebook. For reasons which do not make sense, Mathematica does not render this when run without a notebook): A = Table[k+l, {k,10},{l,10}]; S = GraphicsArray[ Table[ListDensityPlot[LaplacianFilter[A, k], ColorFunction -> Hue, Frame -> False, Axes -> False], {k, 1, 5}]]; Export["laplacians.jpg",S,"JPG",ImageSize->{500,100}];It is not the standard Laplacien as one can see when runnning it on a general matrix: LaplacianFilter[{{a, b, c}, {d, e, f}, {g, h, i}}, 1]The multiplication is illustrated as follows: A = Import["leman.jpg"]; B = Dilation[A,3]; Export["multiply.jpg",Show[ImageMultiply[A,B]],"JPG"] |

Questions and comments to knill@math.harvard.edu