JPEG. As high as we can go on the resolution. Theoretically, to reproduce it at that size at 300 dpi the resolution of the scan would have to be 2290 ppi, but it can probably go as low as 1145 if that's the best we can do...This is just my guess at the needed resolution, we can discuss it if needed
Description
We need to rescan this postcard for a patron who wants to reproduce it at 24 x 42 inches. The current scan would only be about 54 dpi at that size.