How to test if an image is empty?

[Tiemo Hollmann TB]

Hello,

when I put empty into img "foo" the imagedata of img "foo" is still not
empty, there are still any binary data in the image.

I can't test if the imagedata of img "foo" is empty" nor can I test if the
img "foo" is empty. How can I test if I have put empty into an image? Can I
test it binary?

Thanks

Tiemo