Such a Maya feature to compare rendered images. Result displayed into VFB. Which means that you have ZoomIn/ZoomOut control (which is useful in comparing bitmaps) and also access to all VFB's controls like: Save, Copy, Clone, RGBA, ... etc.
Little inconvenience as I indicated is that must clear the sprite buffer if you change the size of the renderer, this is the reason to highlight the script as a beta, but it's ready for use as is. I wrote it just to help Marco Brunetta and I don't plan to extend or update this script, but you feel free to modify and further developed it.
Here are some ideas in this respect which may try:
[-] to have the freedom to add frames of different size in the same buffer, make sprite buffer independent from rendered frame size and/or add UI controls to set fixed buffer size.
[-] change horizontal to vertical order arrangement or...
[-] replace it with matrix/table arrangement like a MaterialEditor by 3x3, 6x4, etc.
[-] if you made thumbnails (to say for your meshes), they could be stored in one file.
[-] also separate UVW maps could be stored in one bitmap file.
[-] compose array of sequences for animated UVW maps.
[-] write vitrual animated preview (without the disk storage), but this also will need to write player to watch the preview.
[-] and so on ...
AutoAppend addition update by David Svantner
to easily render animated sprite sequences.
[-] Added checkbutton to turn on/off AutoAppend function
[-] AutoAppend function was local, now fixed
[-] AutoAppend bug on first run fixed