Hi gepepa.
PhotoDeluxe uses your scanner's plugins to scan a photo, so every scanner has it's own screens and adjustments. Try scanning at lower DPI settings; 72 dpi (dots per inch) is fine for posting photos on your Macs screen or the web.
Also, after you scan--use the send/export-to-disk command to convert from PhotoDeluxe's (Photoshop) default image format to a JPEG or GIF. This command has options to lower the image-quality and thereby make your image smaller too.
Good Luck, T.