Image
Authentication by Detecting Traces of Demosaicing
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Can you spot
the tampered regions in the images on the left? Our algorithm localizes the
tampered regions by finding image portions that do not exhibit traces of
demosaicing (and are therefore likely to be forged). The middle column shows
our analysis signal, and the right column shows the suspicious image
regions. The original images are shown on the right. A careful look shows
our algorithm accurately localized the tampered image regions. The
algorithm is also used to distinguish between computer generated images and
photographic images.
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Abstract
With increasing technical advances, computer graphics
are becoming more photorealistic. Therefore, it is important to develop
methods for distinguishing between actual photographs from digital cameras
and computer generated images. We describe a novel approach to this
problem. Rather than focusing on the statistical differences between the
image textures, we recognize that images from digital cameras contain
traces of resampling as a result of using a color filter array with
demosaicing algorithms. The in-camera processing (rather than the image
content) distinguishes the digital camera photographs from computer
graphics. Our results show high reliability on a standard test set of JPEG
compressed images from consumer digital cameras. Further, we show the
application of these ideas for accurately localizing forged regions within
digital camera images.
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Citation
A. Gallagher,
T. Chen, "Image Authentication by
Detecting Traces of Demosaicing," IEEE Conference on Computer Vision
and Pattern Recognition, Workitorial on Vision of the Unseen 2008 (to
Appear).
Bibtex
@inproceedings{gallagher_cvprwvu_08_authentic,
author = {A. Gallagher and T. Chen},
title = {Image Authentication by Detecting Traces of
Demosaicing},
booktitle = {Proc. CVPR WVU Workshop},
year = {2008},
}
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A Small Tampered Image Database
As part of this work, three original images were tampered with to
produce three images with forged regions.
Original Images:
Kids, Sheep,
Street
Tampered Images:
KidsM,
SheepM,
StreetM
Note that the Sheep image is publically available from a generous
Flickr member (Mark Wales). The Street
image is from Columbia's ADVENT image set (T.-T. Ng, S.-F. Chang, J. Hsu,
and M. Pepeljugoski.
Columbia photographic images and photorealistic computer graphics dataset.
Technical report, Columbia
University, 2005.).
Please cite both my paper and the
Columbia paper if you use these images.
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