Quote Originally Posted by DizzyMoods View Post
This algorithm works just fine and is easy to configure, but it is rather slow when working with big (280x280) arrays.
QwtRasterData::value() is called for every pixel.Think about a plot canvas with 1000x1000 pixels and you will see soon why your code is more or less unusable. But as you wrote that you have equidistant points I don't see any reason for these loops in your code.

Uwe