In general I would suggest you scan your pictures at a bare minimum of 300 DpI, preferably 600 or greater. However depending on the size of the photograph, when scanned, file size may become an issue with larger photographs. For example 600 or even 1200 DpI would be fine on a 2 x 2 inch photograph but if you scanned a 8 x 11 inch photograph at this high resolution, then the resulting file size may be too large to transfer via email.
Scanning at a higher resolution can take a little longer but it's worth the wait for ease of editing. Photographs can be resized easily enough when they are printed. Most photo editing software has a print preview where you can size the printout.
For best results with digital picture frames, save a copy of the file at the highest resolution that your digital frame can support (for example the Texet DPF - 710's highest screen resolution is 480 x 234 pixels). You can save multiple versions of the same picture in different files, for example PiconePrint001.jpg could be a higher resolution file optimized for printing and PiconeDF001.jpg the same picture, but optimised for displaying in your digital picture frame.
