JPEG Ghost Analysis
Definition
A technique (Farid, 2009) that identifies double-compressed patches by resaving a composite JPEG at multiple quality levels and identifying the quality at which the difference between the composite and the resaved version is minimised for a localised region.
- Author
- Hany Farid
- Published
- 2009
- Method
- Multi-quality resave comparison
- Detects
- Localised double-compressed or spliced regions
Common questions
What does a 'ghost' look like in the analysis output?+
A region where the difference between the original and a resaved version is minimised at a JPEG quality level distinct from the rest of the image, appearing as a differently shaded patch across the sequence of resaves.
What is a key limitation of the technique?+
It works best when the pasted region was originally saved at a lower JPEG quality than the final composite, and becomes less reliable when the qualities are close together or the image has been resized.
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