xsnap takes screenshots on Linux using ffmpeg -f x11grab, handling a few annoying details. I have found that ffmpeg's x11grab is accurate, reliable, and doesn't cause any slowdowns. It also paints the mouse cursor onto the screenshot.

Provides three executables. All of them take a screenshot of the current DISPLAY and write to stdout.

• xsnap-png-lossless - outputs a true-color PNG screenshot.

• xsnap-png-256 - outputs a 256-color PNG screenshot. Requires pngquant built with libpng 1.6.

• xsnap-jpg - outputs a JPEG screenshot.

sudo apt-get install ffmpeg x11-utils
git clone https://github.com/ludios/xsnap
./xsnap/bin/xsnap-png-lossless > out.png