http://akhil.nm.ru/tools/bpy/flipbook.py
I made this script for working with a compositor.
This script allows to view a rendered animation in time.
The script renders a curent frame and stores it to the file. When you change the frame my script renders new frame if it not yet rendered. if this frame is rendered my scrip just loads image from your disk.
To clear rendered images you may click to the “clear” button.
To get buttons visible you have to put mouse cursor to the upper script screen border.
Moreover my script show non square pixels corectly.
Put flipbook.py to your scripts directory and got to Script->Render->flipbook.
In fufture I plan to make the histograms and the show every N-th frame feature.