You've basically just described interlacing. For instance, interlaced PNGs start with a 1/8 scale pass/frame and fill in the remaining pixels with the following

You've basically just described interlacing. For instance, interlaced PNGs start with a 1/8 scale pass/frame and fill in the remaining pixels with the following 6. (Frames 1-5 would be required for a 1/2 scale image.)