FLUX 3 Image Klein API - 4K Image Generation and Editing

FLUX 3 Image Klein is a compact image generation and editing model in the FLUX 3 Image family. It combines text-to-image generation, natural-language editing and multi-reference creation, allowing you to create new visuals or modify backgrounds, clothing, styles and settings in existing images. Its strengths include output up to 4K, up to 10 editing references and flexible custom dimensions. Through the PoYo API, these capabilities support product imagery, advertising, illustration and content-creation workflows.

Get an API key from your PoYo dashboard, add credits, and test your prompt, reference images and output settings in the Playground. Use flux-3-klein to generate images from text, or flux-3-klein-edit with 1–10 input images to edit existing visuals or combine references. Once you have confirmed the result, use the same model ID and input parameters in your API request. Save the returned task ID and query its status to retrieve the completed images.

Image generation and editing share the same per-image rates: $0.009 at 1K, $0.014 at 2K and $0.036 at 4K. For example, generating four 2K images costs $0.056. You can explore compositions at a lower resolution before choosing an output tier for your final delivery dimensions. Review the estimate for your current settings in the Playground before submitting a request.

The editing endpoint accepts 1–10 reference images through image_urls, while the text-to-image endpoint takes a written prompt without reference images. For multi-image edits, explain the role of each reference: for example, keep the person from the first image, use the clothing from the second and draw on the setting in the third. Both generation and editing support 1–4 output images per request through n, with a default of one, so you can compare variations of the same idea.

Choose 1K, 2K or 4K resolution, with 1K as the default. The size parameter supports seven preset ratios: 1:1, 4:3, 3:4, 16:9, 9:16, 3:2 and 2:3, defaulting to 1:1. For presets, the resolution sets the long edge to 1024, 2048 or 4096 pixels, and the short edge follows the ratio, rounded to the nearest multiple of 16. You can also request exact dimensions such as 1536x1024; each side must be 256–4096 pixels and divisible by 16, with an explicit matching resolution.

Match the resolution to the longer side of your custom dimensions: up to 1024 pixels requires 1K, over 1024 through 2048 requires 2K, and over 2048 requires 4K. For example, size 1536x1024 requires resolution 2K, and the output keeps those exact dimensions rather than being enlarged to a 2048-pixel long edge. Both sides must remain within 256–4096 pixels and be divisible by 16. A custom-size request is rejected if resolution is missing or does not match its dimensions.

Both generation and editing support PNG, JPEG and WebP through the output_format values png, jpeg and webp; PNG is the default. Choose a format that fits your design, web publishing or asset storage workflow, together with the required resolution, dimensions and image count. The enable_safety_checker setting controls content safety checking and defaults to true. Keep the intended setting explicit in your integration and review generated content and any rendered text before using an asset in a project.

On PoYo, FLUX 3 Image Klein offers generation and editing at up to 4K, up to 10 editing references and exact custom dimensions, making it an option for workflows involving multiple references or larger assets. FLUX.2 provides Pro and Flex models with their own editing endpoints, 1K and 2K output, and up to eight editing inputs. Choose based on your reference count, delivery dimensions and existing integration, then compare results using the same creative task. The family comparison table above summarizes the available interfaces and controls.