Convert multipage PDF to a single image

Question

I have to convert a multipage PDF document to a .png image.

I try with ImageMagick, but I cannot achieve final result:

convert document.pdf document.png 

or

convert -adjoin document.pdf document.png 

This command create N images .png (where N=num of page of document):

document0.png document1.png ....  document(N-1).png 

I need, if possible with a single command, to obtain a single image.

Answer 1

Finally I find THE solution:

convert in.pdf -append out%d.png 

Thanks to this post.

edit

As a plus, the opposite operation is:

convert *.png output.pdf 

or if you have foo1.png, foo2.png..fooN.png

convert foo?.png output.pdf 

Notice that does not work with foo01.png, foo02.png..foo0N.png

Answer 2

+append will put images side by side, i.e. horizontally instead of vertically (with -append)

convert in.pdf +append out%d.png