Show the input / output formats of the processes to the end user.

[l00mi]

Right now the user can not see which processes can be connected because of different kinds of input and/or output formats.

We need to show this best with a color code or similar.

[schmk2]

a) All process items now show their available inputs/outputs (see green box on the left side). This is only preliminary, we would like to design a better solution which makes it more obvious for the user (something like "outlets" on the boxes)
b) The gradient operator now returns the magnitude or phase separately as grayscale image so you can connect it to other algorithms.

[fabiopedrosa]

Thanks!!