#How to do a radial blur in Gimp
Gimp as some function to do blur effects, but it is not clear how to do a radial blur : Blur part of an image, starting from a point, with a radius, and the effect beeing less and less strong the farer we are from the central point.
Here is a sample 
Here is the solution :
- start with an unblur image.
- copy the layer
- on the top layer apply a gaussian blur : "filter -> blur -> gaussian blur". Change parameters so that the image is blurry as you want. This settings would be the blurriest of your final image.
- on the top layer , right click and "add layer mask". On the settings, choose Black
- select gradiant tool, in shape, choose radial. the tools work this way : you select center point, and then the radius. You will probably need some trial and erros before getting the exact effect you want. the Offset is a good option to play with. Still, it's porbably better not to have a big offset, and use a big radius.
Thank you thank you! "Filters"->"Blur"->"Motion blur"->"Zoom" is exactly what I was looking for in a radial blur. The other I would call an azimuthal blur, but realize that term is quite uncommon outside of science circles .