Based on http://ftp-osl.osuosl.org/pub/libpng/documents/pngext-1.5.0.html#C.eXIf, it looks like there is a push to officially add exif support into the PNG image format, it looks like they have defined how to include EXIF data in a PNG 'data chunk' (a standard mechanism 'adding extra data' to PNG files).

Given the work EXIF-related started in #3625 (which addresses #520), is it reasonable to consider this feature request for Pillow?