I am out of the space a little, anyway I would like to run convert, to check why conversion does not succeed I added -verbose option, the output says:
convert: unable to extend cache `X.tif': No space left on device @ cache.c/OpenPixelCache/3874.
convert: zlib failed to initialize compressor -- mem error `Y.png' @ png.c/PNGErrorHandler/1412.
Please add info -- which device. I have several partitions and I don't know whether convert is complaining about local dir (partition), home tmp, or /tmp ?
ImageMagick-6.5.2-7