FIG. 1 is a perspective view of the design for a digital photo frame; FIG. 2 is a front elevational view thereof; FIG. 3 is a rear elevational view thereof; FIG. 4 is a top plan view thereof; FIG. 5 is a bottom plan view thereof; FIG. 6 is a left side view thereof; and, FIG. 7 is a right side view thereof.