01
JPEG is a container of segments
A JPEG begins with a start marker and continues through variable-length segments until the scan data. Safe parsers validate every declared length before moving to the next segment.
Key points
- APP1: EXIF or XMP
- APP2: ICC profile
- APP13: Photoshop/IPTC resources
- COM: comments
- SOS: start of compressed scan data
02
Cleaning without recompression
A segment-level cleaner can remove privacy metadata while copying compressed scan bytes unchanged. Color profiles and orientation deserve special handling because removing them can alter appearance.
What this does not prove
A metadata result describes the fields and structures that the supported parser could read. It does not, by itself, prove authenticity, intent, authorship or the truth of the visible scene.