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Passive Forgery Detection for JPEG Compressed Image based on Block Size Estimation and Consistency Analysis |
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PP: 1015-1028 |
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Author(s) |
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Cheng-Shian Lin,
Jyh-Jong Tsay,
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Abstract |
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| As most of digital cameras and image capture devices do not have modules for embedding watermark or signature, passive
forgery detection which aims to detect the traces of tamping without embedded information has become the major focus of recent
research for JPEG compressed image. However, our investigation shows that current approaches for detection and localization of
tampered areas are very sensitive to image contents, and suffer from high false detection rates for localization of tampered areas for
images with intensive edges and textures. In this paper, we present an effective approach which overcomes above problem, using reliable
estimation and analysis of block sizes from the block artifacts resulting in JPEG compression process. We first propose an enhanced
cross difference filter to strengthen block artifacts and reduce interference from edges and textures, and then integrate techniques from
random sampling, voting and maximum likelihood method to improve the accuracy of block size estimation. We develop two different
random sampling strategies for block size estimation: one for estimation of the primary JPEG block size, and the other for consistency
analysis of local block sizes. Local blocks whose JPEG block sizes are different from the primary block size are classified as tampered
blocks. We finally perform a refinement process to eliminate false detections and fill in undetected tampered blocks. Experiment
over various tampering methods such as copy-and-paste, image completion and composite tampering, shows that our approach can
effectively detect and localize tampered areas, and is not sensitive to image contents such as edges and textures. |
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