perl ./crazy_fast_image_scan.pl --image=/dev/sda
This scans the device /dev/sda.
perl ./crazy_fast_image_scan.pl --percent=0.00001 --image=cdrom.img
This scans the image using 0.00001 (0.001 %) bytes of the image.
This script scans devices or images very fast using random sampling and reports what kind of content could be found. This is useful to decide which image or media could have stuff of interest and allows to prioritize the order of further examinations.
The script uses random sampling and is based on ideas by Simson Garfinkel in a talk http://simson.net/ref/2014/2014-02-21_RPI_Forensics_Innovation.pdf
It calculates the sectors of a given image or device, select n sector samples, seek to the sector positions and read it.