Full color scans and grayscale images can be used as a TIFF or a EPS delivery.
We prefer to deliver detached graphics as a PSD (Photoshop) file.
Photoshop or Illustrator files are of course always good.

Jpg or gif illustrations are intended primarily for display and not for printing. If original jpg images can be converted to a printable format the quality would always be moderate to very poor. Normaly Jpg files are in fact compressed files, and data is usually removed because of the compression. When printing a Jpg illustration you often get a disturbing blockpattern and serrated edges.