Comment 11 for bug 1398521

Could you please test whether the linked ImageMagick libraries work at all?

Steps:
1) open new document, import a bitmap image
2) apply for example 'Extensions > Raster > Swirl'

Do you see any visible changes to the bitmap image on-canvas? The extension will embed the bitmap image first before applying a raster effect (just to let you know in case the bitmap image was linked on import - the original image on the disk won't get modified in any case).