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FLUX.1 Fill [pro]

FLUX.1 Fill [pro] is Black Forest Labs's dedicated inpainting model. It fills masked regions of images using text instructions while preserving the coherence, lighting, and style of the surrounding content.

Image Gen
index.ts
import { experimental_generateImage as generateImage } from 'ai';


const result = await generateImage({
  model: 'bfl/flux-pro-1.0-fill',
  prompt: 'A red balloon on a wooden table.'
});
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Frequently Asked Questions

  • What is the difference between inpainting and instruction-based image editing?

    Inpainting takes an image plus a mask and generates pixels for the masked region only. Instruction-based editing takes an image plus natural language and changes the image without a pixel mask. Fill Pro is built for the first pattern; Kontext Pro and Max target the second.

  • What does FLUX.1 Fill [pro] cost per image?

    See the pricing section on this page for today's rates. AI Gateway exposes each provider's pricing for FLUX.1 Fill [pro].

  • What inputs does FLUX.1 Fill [pro] require?

    An input image, a mask defining the region to fill, and a text prompt describing the desired content for the masked area. This is the standard inpainting input format.

  • Can Fill Pro be used for background extension (outpainting)?

    Yes. By placing the mask at the border or edge of an image, Fill Pro can generate new background content that extends the scene, a technique called outpainting.

  • How does Fill Pro differ from the Kontext models?

    Fill Pro is specialized for mask-based inpainting, generating content for a defined region. The Kontext models (Pro and Max) are specialized for text-instruction-based editing that understands the full image context and makes modifications described in natural language, without requiring an explicit pixel mask.

  • Is FLUX.1 Fill [pro] a chat or language model?

    No. Fill Pro is a dedicated image generation model, not a language model or multimodal LLM. Use generateImage from the AI SDK; it processes image and mask inputs to produce image outputs.

  • Does FLUX.1 Fill [pro] support generating completely new images without an inpainting mask?

    Fill Pro is purpose-built for inpainting. For text-to-image generation without an existing image, use FLUX.1 Pro, FLUX.2 Pro, or other members of the FLUX family.