photograph is edited or digitally enhanced, the modified
portions will have a different noise potential compared to the
rest of the photograph. Splices, drawing, and significant edits
are usually visible as a significantly different noise
Most of the time modified or computer generated photographs can
be identified through human observation. The simplest inspection
approach uses human observations to pull information out of the
image. Inconsistencies usually suggest weather image is
digitally enhanced or computer generated.
highlights and shadows:
Sharp highlights and shadows indicate light direction. When
items are merged into one photograph, they may not have the same
Color tones in anti-aliasing:
Images rarely have sharp, crisp edges. Instead, anti-aliasing
techniques blur adjacent color together. When an object is cut
out of one photograph and pasted into another, the edges may
contain coloring that does not match the new background.
Algorithm: The amount of
error introduced by each save is limited to the 8 by 8 blocks
used by the compression algorithm of JPEG. However, when an
image is (partially) modified, the 8 by 8 blocks containing
modification are no longer at the same level of quality as the
rest of the unmodified blocks. For each pixel, the luminance
value is calculated. Finally, the luminance value of the
brightest pixel is used as the qualifier.
IVK Faux Results: The best
results from IVK Faux are directly dependent on the quality of
image. You may want to know if something was added, but if the
photo is a copy of a copy of a copy, then it will be difficult
to detect different noise potential.
For instance, many pictures are hosted at
Flickr or uploaded on Facebook.
Facebook dynamically resize crop
images and save them at low quality as compared to the original
image whereas Flickr provides
small, medium, large, and original images. The small, medium,
and large are copied images (resaves) created by
Flickr. The "original" is whatever
the user sent to Flickr,
Facebook or any other website, so
the original will be the best quality. Always go for the
original source or get as close as you can to the original
source to improve the image's quality and the IVK Faux results.
Two easy ways to analyze that the image is not an original are
to look at the image size and ascriptions. Most websites add
their logo or web URL to a corner of the photograph. That means
the original picture was resaved and the last modification was
likely the addition of the ascription.
Edits and splices appear as regions with more change. See the
tutorial for more detail.