# ClipBrook

> ClipBrook cuts out art that was generated on a solid background color. The result is a PNG with a transparent background. It runs entirely in the browser: your images stay on your computer, and nothing is uploaded. It is free, with no account and no watermark.

It does not work on photographs. A photo has no key color to remove. The same goes for a render whose background is a scene, a texture, or plain white: there is no single color to measure. For those images a matting model is the right tool, not a chroma keyer.

ClipBrook reads the background color from the outer border of each image, works out how much of that color is in each edge pixel, and turns that into alpha. Background color that has bounced onto the subject is replaced with color taken from further inside the subject. Input is PNG, JPG, or WebP, up to 8192 px on a side and 80 MB per file. Output is PNG with a transparent background. There is no limit on how many files you drop at once.

The cut is only as good as the background the image was generated on, so most of this site is about getting a generator to produce one flat key color. Use blue for plants and foliage. Use red for blue or purple subjects. Green is the wrong key for anything with leaves or plants. Their own green gets removed with the background.

The pages below are HTML. This site does not publish markdown versions of them.

## Tool

- [ClipBrook](https://clipbrook.com/): The cut-out tool itself. Drop files or a folder, adjust three sliders, download the results as a ZIP.
- [Batch background removal](https://clipbrook.com/batch-background-remover-free): Cutting a whole folder in one pass, and what the ZIP contains.
- [Transparent PNGs for print on demand](https://clipbrook.com/transparent-png-for-print-on-demand): Pixel size for a given print size, tight bounding boxes, and straight alpha at the edges.
- [Remove a green screen from AI images](https://clipbrook.com/remove-green-screen-from-ai-images): Keying a green background, what spill does to a green edge, and when green was the wrong choice.

## Prompting guide

- [Prompting guide](https://clipbrook.com/guide): How to ask an image generator for a flat key-color background, and the clauses that keep it flat.
- [Choosing a key color](https://clipbrook.com/guide/key-color): Which of blue, red, or green to render on for a given subject, and why the wrong one eats part of the subject.
- [Midjourney](https://clipbrook.com/guide/midjourney): Prompt, and the `--no`, `--style raw`, and `--stylize` flags that keep a background flat.
- [Stable Diffusion (SDXL)](https://clipbrook.com/guide/stable-diffusion): Prompt, negative list, CFG 5 to 7, and weighting the background phrase.
- [FLUX in ComfyUI](https://clipbrook.com/guide/flux-comfyui): Prompt, why the negative prompt does nothing at CFG 1, and keeping FluxGuidance at 3.5.
- [Gemini (Nano Banana)](https://clipbrook.com/guide/gemini): Prompt, the hex codes it respects, and one-line replies that fix a staged scene.
- [DALL-E 3 in ChatGPT](https://clipbrook.com/guide/dalle): Prompt, getting it past the rewriter unchanged, and the contact shadow it adds.
- [Ideogram](https://clipbrook.com/guide/ideogram): Turning Magic Prompt off, the prompt, and where the negative prompt is hidden.
- [Leonardo.Ai](https://clipbrook.com/guide/leonardo): Switching off Prompt Enhance and PhotoReal, and picking a flat-leaning model.

## Background

- [Chroma key vs. background removal](https://clipbrook.com/compare): The two methods on the same renders, with the same 400 pixels shown three ways.
- [Why ClipBrook runs only in your browser](https://clipbrook.com/why-browser-only): There is no server to upload to, and how to confirm that in your browser's network panel.
- [About](https://clipbrook.com/about): Who wrote it and why.

## Optional

- [Privacy](https://clipbrook.com/privacy): What is stored on your device, and what the site's analytics records.
- [Terms](https://clipbrook.com/terms): Free and provided as-is. Your files stay yours.
- [Open source](https://clipbrook.com/open-source): The cutting engine is AGPL-3.0. Where the repository is and how to run the keyer from the command line.