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.