Preview Image-JPEG

ComfyUI's stock Preview Image node sends the full, uncompressed image over to your browser every time it runs. That's fine on localhost. It's noticeably not fine when your ComfyUI instance is running somewhere remote and every preview has to travel over a real network connection - a slow home upload, a VPN, or any setup where ComfyUI's backend and your browser aren't sitting on the same machine. This node exists specifically for that situation: it compresses the image to a lower-quality JPEG before sending it, so the preview shows up faster, at the cost of some visible compression artifacts in what you're looking at.

What it actually trades off

The author's own description is direct about the purpose: it converts the input to "low-quality JPEG for preview to reduce network pressure." That's the entire feature. You're not getting the underlying image data changed or degraded for anything downstream - because this node has no outputs at all, it can't feed anything further in your graph. It's purely a display step, a dead end by design. Whatever quality loss you accept here only affects what you see in the ComfyUI interface; it has zero effect on your actual saved files or any other branch of your workflow.

That "no outputs" detail is the clean way to tell this apart from the pack's other JPEG node, To JPEG: that one does output an image and is meant for cases where you want the compression artifacts to persist into further processing. This node is strictly for looking at something quickly without waiting for a full-resolution transfer.

Inputs and outputs that matter

• images (required) - the image (or batch) to preview.
• quality (required, 0–1, default 0.5, step 0.01) - how aggressively the preview gets compressed before it's sent to your browser. Lower is faster to transmit and more visibly artifacted; higher stays closer to the source at the cost of a larger transfer.

There are no outputs - this node is a terminal display step, flagged as an output node in ComfyUI's terms.

Installing it

ComfyUI Manager: search ComfyUI-ReplenishNodes, install, restart. Or manually:

cd ComfyUI/custom_nodes
git clone https://github.com/hben35096/ComfyUI-ReplenishNodes

No model downloads or extra dependencies documented for this node.

Where people get tripped up

Judging final image quality from this preview. Because the quality knob is deliberately biased toward "fast, not accurate," don't use what you see here to make final decisions about denoise strength, detail, or color - those artifacts are an artifact of the preview transport, not your actual output. Check the real saved file, or a stock Preview Image node, before making a judgment call based on what this node shows you.

Expecting it to speed up local runs. If your ComfyUI is running on the same machine as your browser, the network-transfer savings this node is built for don't really apply - the bottleneck it targets barely exists locally, so you likely won't notice much difference over the stock preview node in that setup. It earns its keep specifically on remote or bandwidth-constrained instances.