IMAGE Preview in Background (Legacy) @ vrch.ai

The "(Legacy)" in this node's name is doing real work: the IMAGE Preview in Background (Legacy) node is the older channel-based version of the pack's fullscreen preview, superseded by the IMAGE Preview in Background node. But "legacy" here doesn't mean broken - it means the version that old workflows load, and the version that still has a couple of features the new one dropped. If you're opening a shared workflow built months ago, this is probably what you'll see.

What it is

Its job is the same as the new node: feed it images and it pops a window that displays them as a fullscreen-style background. The display_option picker is shared too - original, fit, stretch, or crop decides how the image is fitted into the window - as is background_display (default on), the master toggle for showing the background at all.

What sets the legacy version apart is the channel integration. It has a channel field (1–8), the same channel number the pack's viewer nodes use, so it can tie into the display channel system rather than just showing whatever's wired in. It also carries refresh_interval_ms (default 300) for how often it re-checks the input, and batch_display plus batch_display_interval_ms for cycling through a batch - plus batch_images_size (default 4), which controls how many images the batch viewer considers at once. That batch-size knob is the one feature here that the new node doesn't expose.

The short version of the choice: if you're building something new, reach for the non-legacy node - it's the maintained path. If you're loading a workflow that already uses this one, leave it alone. Legacy nodes like this exist so shared graphs keep working, and there's no real reason to migrate unless you specifically want the leaner version. It's the same spirit as a pack keeping old node names around for backward compatibility: don't fight it, just know which one you're looking at.

How to install

Install is identical across the pack:

cd ComfyUI/custom_nodes
git clone https://github.com/VrchStudio/comfyui-web-viewer
cd comfyui-web-viewer
pip install -r requirements.txt

restart ComfyUI, or search "ComfyUI Web Viewer" in ComfyUI Manager. Windows portable users run the pip line with python_embeded\python.exe. No models involved.

Common issues

Troubleshooting matches the preview family: it's a browser popup, so on Chrome over a LAN you may need the README's insecure-origin flag for the window to load, and if you're viewing from a remote origin, a CORS error means relaunching ComfyUI with --enable-cors-header. Other than that, the node is a quiet display sink - set your display option, enable batch display if you're flipping through a set, and let it wallpaper your screen with output.