RC Preview Image (Transfer Metadata)

ComfyUI's default image preview shows you one image at a time, and if you're editing a generated render you often want to compare - original in, edited out - without building a separate comparison widget. RC Preview Image (Transfer Metadata) does two things at once: it displays the source and target images side by side in the node's output, and it stamps the source image's workflow metadata onto the preview, so the whole "drag it back into ComfyUI" trick keeps working.

It's the preview-only sibling of the pack's RC Save Image (Transfer Metadata) node. Same metadata-transfer idea, but it writes to ComfyUI's temp folder and shows you a comparison instead of committing a permanent file.

How it works

The node reads the PNG text metadata from a source file in your input folder, then saves your target image to the temp directory with that metadata attached. Crucially, it returns both images in its UI output - the source thumbnail and the saved target - so you get an automatic before/after in the graph. The implementation also hashes the source file and forces re-execution when it changes, which means swapping your source image doesn't require manually re-running the node.

The inputs that matter

• target_image - the image you're previewing (usually your processed/edited result).
• source_image_file - a dropdown of image files in your input folder, with upload support. Pick the original whose metadata you want to carry and whose thumbnail you want to compare against.

There are no outputs and no filename prefix - it's a terminal preview node, deliberately minimal.

How to install it

Ships with the RC Image Compositor pack:

cd ComfyUI/custom_nodes
git clone https://github.com/kj863257/ComfyUI_RC_Image_Compositor
cd ComfyUI_RC_Image_Compositor
pip install -r requirements.txt

Restart ComfyUI, or search "RC Image Compositor" in ComfyUI Manager. Dependencies: pillow, numpy, opencv-python - nothing heavy.

Common issues

The same caveat as its save sibling: the source file has to actually contain text metadata. If you picked a stripped PNG as the source, the node still shows the before/after comparison - that part always works - but there's no workflow to transfer, so the preview just won't be re-loadable. That's not a bug; it's "garbage in, nothing out."

Second, the preview writes to temp, so don't go hunting for it in your output folder. If you want a permanent, metadata-carrying file, that's RC Save Image (Transfer Metadata). Use this node as the check-your-work step, the save node as the commit.

And one genuinely useful habit: since this node shows source + result side by side, it doubles as a poor-man's A/B viewer during compositing - drop it at the end of a branch to eyeball whether that blend mode is actually doing anything.