🔶 Preview Stacking

When you're running Chaosaiart's frame-by-frame animation setup - one image generated per queue run, cached and fed back in as the next frame's img2img source - you're not watching a video render in real time, you're watching a queue of individual generations tick past one at a time. This node exists to make that less painful to monitor: it stacks each new frame's image into a running preview buffer as they come in, so you get a growing strip of what's been generated so far instead of just the single most recent image.

It's a small quality-of-life node rather than anything that touches your actual output - nothing here affects generation, it just gives you a live view while a long batch runs. Handy for catching a checkpoint swap or ControlNet window that fired at the wrong frame before you've burned through your whole queue waiting for it to finish.

Inputs and outputs

• restart - required, RESTART type. Wire in a reset signal (from Chaosaiart's convert node) so the preview buffer clears and starts fresh at the beginning of a new sequence, instead of carrying over frames from a previous run.
• image - required IMAGE, the current frame to add to the stack.
• Preview_Max - required INT, default 50, range 0–10000. Caps how many frames the preview holds at once - set it to roughly how long your sequence is, or lower if you just want to sanity-check the first stretch without the buffer growing indefinitely.
• Output: IMAGE - the stacked preview, which you'd typically send into a standard Preview Image or Save Image node to actually look at.

Installing it

ComfyUI Manager: Install via Git URL → https://github.com/chaosaiart/Chaosaiart-Nodes, the method the README documents directly. A title search for "Chaosaiart" should also find it.

Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/chaosaiart/Chaosaiart-Nodes

Linux (activate your venv first, if you use one):

pip install opencv-python
pip install tqdm

Windows: run the bundled Install_windows script instead. Restart ComfyUI afterward. No downloads needed - it's just stacking images you're already generating.

Common issues

Buffer keeps growing across unrelated runs. Without a restart signal wired in and actually firing at the start of a new sequence, the stack keeps accumulating frames from whatever you ran before - you'll see old frames mixed in with a new animation. Make sure your RESTART source (from convert) is actually triggering when you expect.

Memory grows with Preview_Max on long sequences. This node is holding images in memory to build the stack, not writing them to disk - if you set Preview_Max very high for a long batch, expect it to cost RAM proportionally. Bring it down if you just need to eyeball recent frames rather than the entire run.

Whole-pack import failures. All Chaosaiart nodes, this one included, share a single Python module - a failed opencv-python/tqdm install takes the entire pack offline. Check the ComfyUI startup console for an import error first.