Hello, >----- Mail original ----- > > During Image Processing, I have an extracted small matrix > > Mat = > > 152 149 151 > 159 151 147 > 158 152 152 > > and a simple flipped sobel mask > > Gy = > > - 1. - 2. - 1. > 0. 0. 0. > 1. 2. 1. > > To calculate the gradient in y-direction, I multiply elementwise (and would > sum later if the values were right) > > Gy.*Mat, which funnily gives > > 104 214 105 > 0 0 0 > 158 48 152 > > Why aren't the first row values negative (They even appear morphed somehow). >
Because a) numbers in Mat are encoded as unsigned integers (they are displayed without decimal dot), + b)in Scilab, integers win over floats. + c) in Scilab, overflowing integers are wrapped, not ceiled nor floored. You will get want you likely expect with Gy .* double(Mat) >Scilab help shows that .* may calculate the kronecker product of the two >matrices. Could you give us a pointer where this is written? The kronecker operator is .*. >How do I calculate the real element wise multiplication? With .*, after casting Mat to decimal encoding. HTH Samuel Gougeon _______________________________________________ users mailing list users@lists.scilab.org http://lists.scilab.org/mailman/listinfo/users
