OpenAI has published a guide to writing prompts for the GPT Image 2.6 image models on its developer site. South Korea’s AI Times reported that the guide was published on 7 November local time.

There are two models. The smaller Flare suits workflows where speed matters, the guide says, while the base model Sunburst suits more detailed images and precise edits. Both can generate and edit images and produce a transparent background.

Say what changes and what stays

The guide advises stating first what the image is for, then describing the subject, composition, style and constraints. Text that should appear in the image goes in quotation marks, and the prompt specifies its position, typeface and how many times it appears. Spelling should still be checked in the finished image.

An edit prompt should say ‘change only X’ and list what to preserve, such as a person’s identity, geometry, layout and lighting. When several images are included, the guide advises numbering them and stating each one’s role, for example subject, style or background. Changes are made one at a time, with the previous result used as the input for the next edit.

If part of the image must stay identical down to the pixel, the guide advises combining the approved edit with the original image.

Users can also mark the area to edit. Along with the original image, they send a transparent PNG of the same size with the target circled (the markup parameter). In OpenAI’s own example, both models turned a vase in a kitchen image cobalt blue and removed the marking circle. The guide still advises comparing the rest of the image with the original to catch unintended changes.

Planning and detail are set separately

The complexity setting determines how much the model plans the composition before rendering. There are three levels, and the default is the highest. The quality setting, by contrast, controls detail such as texture and small text.

If the layout is wrong, the guide advises comparing complexity levels without changing quality. If the layout is right but small text is unclear, compare quality levels. Higher complexity does not always show: in an image that is already precisely specified, the difference may be small. Edits to a single detail are best begun at the lowest level.

When generating images, users can also choose an editable SVG vector image or a GIF animation as the output. For charts, the guide advises checking labels and data accuracy as well as appearance.

The guide covers the API, but its principles also apply to ChatGPT

The guide is written for OpenAI’s API, where the models are named gpt-image-2.6-flare and gpt-image-2.6-sunburst. AI Times reported that some model choices and advanced settings cannot be adjusted in ChatGPT, but that the basic principles apply there too.

For those moving from earlier models, the guide advises starting by comparing results with the same prompts, images and settings. Edit requests should omit the input_fidelity parameter, and GPT Image 2.6 does not support the reasoning.summary field. Prices are listed on OpenAI’s image generation pricing page.