// EXAMPLE color transform (gray-scale)
// Create a gray-scale image by taking a linear combination of the RGB
// values of the input image as a gray-level intensity. 
//
// Port First_In: 2D Image to transform
// Port Second_In: 4x4 matrix to provide colormap transform
//
// Port First_Out: Transformed 2D byte Image
//

// Extract input transform matrix
   mat := scalar_lattice_in(Second_In);

// Take linear combination of input matrix channels
// using tensor product.
   v := (double) [mat[0][0], mat[0][1], mat[0][2]];                   
   gray := First_In +.* v;

// Scales the range to 0..255
   mx := max(max(gray));
   mn := min(min(gray));
   if (mx == mn)
	mn -= 1;
   gray = (gray - mn) * (255 / (mx - mn));	

// Assign to known output name
   First_Out := (byte) inside([gray, gray, gray]);