I scanned some family ancestor portrait watercolours (*)(about A4 sized) at 1200dpi lossless PNG, although when I took them to be printed the print shop said "Can we have JPGs?". Sigh. Although, once framed, the copies were indistinguishable from the originals at normal viewing distance.
(* I was giving them to a relative who actually has children and wanted some copies to display).
Most software can vary the amount of JPEG compression. I wonder how much information is lost in JPEG with minimum compression (maximum file size) compared with a lossless compression format like PNG or TIFF - or BMP which is not compressed at all (lossily or losslessly) so an m x n file is always exactly m x n x bit-depth bytes long (excluding the header!).
Using Paint Shop Pro, I can't see any difference between JPEG with compression of 1 (minimum compression) and PNG. Compression 10 may show slight ringing. Anything above 30 is getting pretty repulsive.
Just use PNG and convert it to JPEG later if required.
+1. S'what I did.
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