New in Wolfram Mathematica 7: Built-in Image Processing & Analysis  previous | next 
Process Different Parts of an Image Differently
This combines matrix and image operations to create a composite image.
In[1]:=

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s = Blur[imag, 4];
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g = GradientFilter[imag, 2] // ImageAdjust;
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ds = UpperTriangularize[#, 120] & /@ 

  ImageData[s, Interleaving -> False]; dg = 

 LowerTriangularize[#, -120] & /@ ImageData[g, Interleaving -> False];

dh = UpperTriangularize[#, -119] & /@ (LowerTriangularize[#, 119] & /@

      ImageData[imag, Interleaving -> False]);
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Image[ds + dg + dh,  Interleaving -> False]
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