Photoshop
Open terrain.png (or whatever image you want to upscale) go to Image > Image Size. If you want 32x, then just double the overall size. (256 to 512 etc etc.) However, unless you want Photoshop to anti-alias everything and make it look like garbage, be sure to select "Nearest Neighbor - Preserve Hard Edges" at the bottom in that window. That way, everything upscales all nice and clean and you can build right over top of it.
Open terrain.png (or whatever image you want to upscale) go to Image > Image Size. If you want 32x, then just double the overall size. (256 to 512 etc etc.) However, unless you want Photoshop to anti-alias everything and make it look like garbage, be sure to select "Nearest Neighbor - Preserve Hard Edges" at the bottom in that window. That way, everything upscales all nice and clean and you can build right over top of it.