RenderZero Prompt Bridge

Every RenderZero image workflow has exactly one of these, and it's the first thing the platform's UI talks to. When you type a prompt, pick "16:9," and choose "1K" on the RenderZero side, those choices land in this node and come out the other side as a prompt string plus concrete pixel dimensions. It's the contract between RenderZero's friendly forms and your text encoder, your latent-size inputs, and your sampler's seed.

How it works

The node is a lookup table with a prompt pass-through. It resolves your aspect_ratio and image_size against a fixed table of thirty combinations and returns the matching width and height. That's the entire mechanism - no resizing, no model involvement, nothing clever. The table is the product: every size was picked to be model-friendly. "1K" 16:9 resolves to 1344×768, which sits right in SDXL's native training range and is a comfortable Flux size; 480p 9:16 gives 480×832, a real phone-format canvas; and the 2K and 4K tiers exist for workflows that are explicitly built to generate big. If you've ever generated at 1920×1080 on an SDXL model and wondered why the anatomy fell apart, this is the fix - someone already did the "don't stretch past native resolution" math for you.

The inputs that matter

• positive_prompt (STRING, multiline) - your prompt, passed through untouched.
• aspect_ratio - six choices: 1:1, 3:4, 4:3, 9:16, 16:9, 21:9.
• image_size - five tiers: 480p, 720p, 1K, 2K, 4K.
• seed (INT) - the seed RenderZero controls. It randomizes per generation unless you lock it, which is how the platform lets you reroll without editing the graph.

The outputs are positive_prompt, width, height, and seed. Feed the prompt into your CLIP/text-encoder, feed width/height into your latent-size node (Empty Latent Image, or your model's own size inputs), and feed seed into the sampler. The whole node is four numbers and a string - but they're the four numbers that make a workflow run at the right canvas instead of a random one.

Installing it

Same one-repo install as the rest of the pack. ComfyUI Manager - search "renderzero-comfyui-nodes" - Install, restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/jamesstothard/renderzero-comfyui-nodes renderzero_bridge_nodes

Restart, done. No extra dependencies, no model files, nothing to download. It's a pure-Python shim, which in this ecosystem is the nicest thing a node can be.

Common issues

The gotchas are all about workflow rules rather than failures. RenderZero insists on exactly one Prompt Bridge per image workflow, and you must not include the video bridge nodes in the same graph - mix the contracts and the platform will reject the workflow before it runs. Also, remember this is the image-side bridge; if you're doing video, RenderZero Video Prompt Bridge is the node you want, with its own resolution tiers. If your outputs ever look off, check that you actually wired width and height into the model's size inputs instead of assuming the sampler inherits them - the bridge resolves numbers; it doesn't whisper them into the graph by magic.