If some of the box numbers have faded take a good camera with a macro setting and take the highest res photo you can using a tripod.
First get a background that is a dark blue and lay the sheet down,
Close the lens F-stop as far as it will go (8 on most cameras) Bracket your exposures, (take the first photo at whatever exposure time the camera auto sets itself to, then one with the shutter one stop faster, and one with the shutter one stop slower), do the same in different light and at different angles then start with the photo shop and I believe more codes will be visible.
Bracketing your exposures allows areas that are darker to receive more exposure and brighter areas to receive less exposure thus covering both sides as well as the middle.
Shutting down the lens F-stop requires that the shutter be open longer which allows more light to reach the imaging chip which allows for more detail...