JPEGsnoop is a free image decoder that wrings every drop of data that can be extracted from JPEG images. It's compact and fully portable, so you can take it along with you on a USB drive or other memory device and run it from any compatible Windows machine without having to install it. It can open not just JPEGs but also AVI, DNG, PDF, and THM files, and it also extracts embedded JPEG files. As for the data it extracts, we didn't know that JPEGs contained so much information.
We extracted JPEGsnoop's compressed download and opened the program's plain but businesslike user interface. This program offers online assistance via the Help menu, but its old-school Windows functionality basically explains itself. We clicked the File menu and selected Open Image. Our image appeared as a thumbnail in the bottom preview panel, while the main view was filled with information so detailed that much of it won't be of use to anyone but graphics professionals, unless you can make good use of the histogram stats and code lengths displayed in various Huffman Tables. But this tool is clearly aimed at professional users like photographers, Web designers, and programmers. It offers versatile features such as the ability to process batches of files, save log files, and export JPEG and TIFF files. JPEGsnoop offers many sophisticated options; for instance, we were able to select between a fast, low-resolution process and a slower but more thorough and accurate scan. Among the program's more prosaic options are selectable tool tips known as Coach Messages.
For those who need it, JPEGsnoop is just the thing, especially since it's compact, portable, free, and easy to use.
From Calvin Hass:
JPEGsnoop is a free, portable detailed image decoder that examines any file type containing JPEG compressed images and reports a wealth of hidden information. Can even be used to determine the source of an image or whether it has been edited. Opens .JPG, .THM, .AVI, .DNG, .PDF and extracts embedded JPEG files. JPEGsnoop reports countless details, including image quality, EXIF / IPTC metadata, huffman table decode, etc.
JPEG marker decoding;
JPEG image display;
Optional command-line interface.
What's new in this version:
Fixed Win XP launch issue
Improved error handling with missing User Database