When i try to use this command (present on imagemagick) on big images i have problems.
For example if you go on
imaging-resource and you download an image taken with the Nikon D800.
convert D800...jpg D800....png
From an image of 21.5 mb on /tmp is present a temporary file of 275Mb!
Also, in the end, the png isn't made, remain 0 byte.
Note:
Now i using openbsd 5.1 but i have this problem since the 5.0 with the difference that now the /tmp have more space so at least don't said that the /tmp is full!