When a graphic is imported, it has a resolution of a certain number of dots per inch. After importing, you can see this number under the Technical Attributes in trxn SE78->Graphics->Bitmap. The attributes will also tell you the picture size.
When you include this graphic in the Smart Forms (this is also the trxn id), go to your form, and then the node where you want the graphic. You may have a node under Pages and Windows -> PAGE New Page.
Then in the tab Background Picture, the Output Attributes -> Resolution controls the size of the picture or graphic that is output in the form. If you keep this resolution the same as that in the imported graphic (that you saw in SE78), then the graphic in the output form will have the same size as that of the imported graphic. If you want to increase (or decrease) the output size, then you reduce (or increase) the resolution in Smart Forms -- this will result in stretching (or contracting) the graphic in the output form.
You can also test this in SE93 by testing the trxn that uses the form in SE93.
This was first published in August 2005