It does take a long time. But that doesn't explain/fix the black part at the bottom of the picture.
I'll have look at the 'large file' examples, tnx for that!
I'm trying to convert an image with the "convert" commandline-tool. When I try to convert (resize) an image the result image is partially black. It looks like the upper part of the image is processed well. The image I'm trying to convert is around 5 Mb. When I resize the picture first with Irfanview ...