The same JPEG, recorded as being oriented some other way.
Only the tag is touched. The scan is copied across byte for byte, so
the picture is not decoded, not re-encoded, and loses nothing: turning
an image this way costs the same whether it is done once or a hundred
times. Where the file already names an orientation this is a two-byte
write and the file does not even change length.
The same JPEG, recorded as being oriented some other way.
Only the tag is touched. The scan is copied across byte for byte, so the picture is not decoded, not re-encoded, and loses nothing: turning an image this way costs the same whether it is done once or a hundred times. Where the file already names an orientation this is a two-byte write and the file does not even change length.