An open-access website called fotoforensics.com analyzes digital images to detect potential alteration. One of the techniques offered at the site is Error Level Analysis.
According to the site’s tutorial on ELA:
Error Level Analysis (ELA)permits
identifying areas within an image that are at different compression
levels. With JPEG images, the entire picture should be at roughly the
same level. If a section of the image is at a significantly different error level, then it likely indicates a digital modification …
ELA highlights differences in the JPEG
compression rate. Regions with uniform coloring, like a solid blue sky
or a white wall, will likely have a lower ELA result (darker color) than
high-contrast edges. The things to look for:
Edges. Similar edges
should have similar brightness in the ELA result. All high-contrast
edges should look similar to each other, and all low-contrast edges
should look similar. With an original photo, low-contrast edges should be almost as bright as high-contrast edges.
Textures. Similar textures should have similar coloring under ELA.
Areas with more surface detail, such as a close-up of a basketball,
will likely have a higher ELA result than a smooth surface.
Surfaces. Regardless of the actual color of the surface, all flat surfaces should have about the same coloring under ELA.
More @ Global Research
No comments:
Post a Comment