GPS location data survives image resizing in sips but not Pillow, audit finds

A web developer testing image-processing tools discovered that GPS metadata behaves inconsistently depending on the tool used to resize or convert photos. Apple's built-in sips utility retained GPS coordinates in all output formats it produced, including JPEG, PNG, and resized files, while Pillow stripped location data by default unless original EXIF was explicitly passed back. A particularly notable finding was that sips-generated PNG files stored GPS data twice — once in the EXIF chunk and once in an embedded XMP packet — meaning a scanner checking only EXIF would falsely report the file as clean. The developer built a directory scanner that checks both EXIF and XMP for GPS entries, returning an error if either contains location data or if a file cannot be read. Four remediation approaches were evaluated, with targeted GPS IFD deletion identified as the cheapest option for JPEG files since it avoids a full re-encode and preserves pixel data.