JPEGsnoop by Calvin Hass provides a deep insight into the internals of JPEG files. Also the program identifies digital cameras and image editing software by their characteristic quantization tables.
In the last post I demonstrated how a the origin of an image could be concealed by small changed to the quantization tables. In this article I'm attempting to make a drawing look like a photograph - at least in regards to its quantization tables.
Blog reader Mark Cox pointed out that it is easy to forge a quantization table. That's true! In this article I provide a first example on how the tables can be manipulated in order to conceal the origin of an image.
With this blog post I release a small script that helps in comparing quantization tables of JPEG images.
In an earlier post I described the structure of quantization tables in a JPEG file. Closer inspection reveals that there are two different ways to store the information.
In an earlier post I refered to a paper by Hany Farid which analyzes quantization tables found in JPEG file headers. As I'd like to introduce his method in my lab I'm taking a closer look.
The paper Digital Image Ballistics from JPEG Quantization by Hany Farid describes how digital stills can be attributed to camera makes due to certain differences in the implementation of JPEG compression.
