Cross-Reference Table (Xref)

Related terms

ByteRange

A four-integer entry in a PDF digital signature dictionary specifying which byte ranges of the file were hashed when the signature was...

Content-Aware Fill

An image editing feature (Photoshop from CS5; AI-driven from version 22.0) that replaces a masked region with synthesised pixel content matching the...

Copy-Move Detection

A class of image forensics algorithms that search for duplicated regions within a single image, indicating a patch-and-conceal manipulation. Implemented via block...

Error Level Analysis (ELA)

A technique that re-compresses a JPEG at a controlled quality setting and maps the pixel-level difference between the re-compressed and original images....

EXIF (Exchangeable Image File Format)

A metadata standard embedded in JPEG and TIFF files by capture devices. EXIF fields record camera make and model, lens data, exposure...

Incremental Update

The PDF mechanism by which an editing application appends new or modified objects to the end of an existing file without overwriting...

JPEG Ghost Analysis

A technique (Farid, 2009) that identifies double-compressed patches by resaving a composite JPEG at multiple quality levels and identifying the quality at...

PRNU Fingerprint

Photo Response Non-Uniformity: the unique pattern of pixel-level sensitivity variations in a camera sensor, which acts as a device fingerprint. Used to...

XMP Metadata

Extensible Metadata Platform (ISO 16684), an XML-based metadata stream embedded in many PDF and image files alongside the information dictionary. Discrepancies between...

Explained in

• PDF Metadata Forensics and Document Image AuthenticationThe index structure at the end of a PDF file that maps each object number to its byte offset. Multiple xref sections indicate incremental updates, each corresp...