@Kamel 

since i dont know the exact position of the elements that i want to extract from the original list,

i need to find a command that creates the new list (listx) only by looking at the values of the elements.

hey duncan,

thanks for the answer, thats kind of what i was looking for!

hey duncan,

thanks for the answer, thats kind of what i was looking for!

the convolution command of the ImageTools does the convolution, but my question was more related to the kernel, which is used for the convolution: how do i create an gaussian kernel with variable sigma, that i can use then to convolve with my image? (in the end i want to convolve my image with the matrix that discretely approximates a gaussian)

hey robert,

thanks for the answer. what you basically suggest is to do it pixel or pointwise, right?! this should work if the plateau is really flat (in the example you mention: if y=1 for a<x<b), but does it also work for a slight gradient in the plateau?

hey robert,

thanks for the answer. what you basically suggest is to do it pixel or pointwise, right?! this should work if the plateau is really flat (in the example you mention: if y=1 for a<x<b), but does it also work for a slight gradient in the plateau?

@John May 

works brilliantly! thanks a lot!!!

@John May 

works brilliantly! thanks a lot!!!

hey john,

thanks for your answer. yes, indeed, thats more what i would have expected.do you have an

idea, how to calculate the variance of the histogram (or the array)?

hey john,

thanks for your answer. yes, indeed, thats more what i would have expected.do you have an

idea, how to calculate the variance of the histogram (or the array)?