If i open image saved like gif, (even with the Xnview plugin) i can see it, but i couldn't work with it since almost all menù become greyed and tools not more usable 
Same if i use "transparent colour" the choosed colours became transparent but i could no more correct the image,
exemple i have a some pics of nuclear sides... i need it pure black and white on a transparent background to use in a collage
If i eliminate first the colours,it become difficult make the sky transparent .
If i use transparent colours to eliminate the sky,i could not anymore convert to black and white...some suggestion
