A C program to measure the difference between two JPEG images. Also measures the brightness of the first image. A component of my Raspberry Pi webcam.
Requires libjpeg. Install libjpeg on Raspberry Pi (raspbian) as follows:
apt-get install libjpeg62
apt-get install libjpeg62-dev
Build on the Raspberry Pi using ./build.sh.
Pass the current and previous webcam images:
./analyse current.jpg previous.jpg
Return format is brightness difference e.g. 245354 1344. The numbers are always non-negative integers, no higher than 1000000 (one million).