Custom Fields of image datatype

Custom Fields of image datatype are rendered as Textbox instead of file section

You are meant to insert URL of image in that custom field.

If custom field is Image type, then on printed documents, you will see the actual image.

I tried it. but the image is not making its appearance on printed documents also.please help!
In fact I think why separate field for image.
why not implement it in attachements itself

I mean if I select an Image as an attachement then its Thumbnail is shown and if its any other file like pdf invoice its details are shown as thumbnail.

Even better, the image is shown as background