MiniMax announced H3-Image on 10 November in a blog post and on the model card on Hugging Face. Both sources are the company’s own and contain no independent measurements. The same model generates images from a text description and edits one or more reference images.

MiniMax calls a 4096 × 4096-pixel image a 4K image. Its blog says H3-Image produces one in under 10 seconds, up to five times faster than mainstream solutions on the market. The blog names no point of comparison and does not say what hardware MiniMax used to measure the time. The model card does not mention the time at all.

The company also says the model follows instructions better than any other open-weight model. MiniMax presents no benchmark results to support the claim.

Six steps from noise to image

A diffusion model builds an image from random noise by correcting it step by step. The model card says H3-Image is distilled to six sampling steps, meaning it is trained to produce an image in six runs of the model. Nor is the model run twice at each step, as is usual with classifier-free guidance. Cutting the steps was part of post-training, which also included reinforcement learning and prompt expansion, the blog says.

The diffusion transformer that generates the image has 33.1 billion parameters. It is based on the H3 family architecture without the audio layers. An unmodified MiniMax-H3 text encoder interprets the text. The model card says the model works with images of roughly 4–20 megapixels and performs best at about 16 megapixels.

The model needs a detailed English description of the whole image. In MiniMax’s API, the company’s H3-Image-Context-IR service expands a short prompt written in any language into such a description. For text-to-image generation, users can expand the prompt on their own server with a separate MiniMax-H3-Image-PE model. The model card’s editing example uses MiniMax’s API for the expansion.

Weights take up more than 130 GB

The image model’s files take up 68.65 GB. It also needs the 66.7 GB text encoder, downloaded from the MiniMax-H3 repository. The model card says the server can run on a single GPU or split a request across several GPUs to reduce latency. vLLM-Omni supports Nvidia’s H200 and AMD’s Instinct MI350X, among others, the card says. The card includes instructions for SGLang, vLLM-Omni, diffusers and ComfyUI.

Use of the model is governed by MiniMax’s own community licence. Users request the separate written permission described in Section IV of the licence through a MiniMax form.

H3-Image is available as a ready-made service through MiniMax’s API, MiniMax Code and the Hailuo app. The blog says the service’s standard mode is 1.5–2 times and its Highspeed mode 3–4 times faster than mainstream tools. The company puts the price at 50–70 per cent of the price of comparable tools. The blog does not name these tools either. During launch week, images at 4K and larger cost half the list price.