Place the elements before the picture exists
The product belongs on the right, the top stays clear for a title and light falls from the side. You can describe that, but FLUX 3 Image also lets you assign rectangular boxes to important elements. Prepare the layout yourself or with a language model, then move the selected areas. Black Forest Labs demonstrates the workflow in a browser and offers it through an API.
For a cover, that is practical help. What use is a great illustration if the face sits exactly under the title and cropping to a square removes the main object? Here, we handle placement before generating.
Imagine an album called “Late Light”
We have an idea for a fictional album cover: a translucent orange solid above a navy surface, casting a long shadow. Move the object slightly right and leave the top quarter for “Late Light.” Even a few rectangles let us consider whether the composition will read as a thumbnail.
Add the title later in a graphics editor. You control typeface, spacing and wrapping. For a portrait teaser, arrange the elements again: trimming the sides of the square may remove space the design relied on. This is a suggested project; we have not generated the image yet.
A box can mark where to make a change too
BFL’s documentation uses coordinates from 0 to 1000, regardless of image size. A box can identify a color change, move, replacement or removal. The model accepts up to ten reference images — material showing the desired appearance — and offers 4K output.
There is a detail to remember: the box defines position and scale, but is not a hard mask. An object may extend slightly beyond its boundary. Leave some breathing room beside the title. BFL claims to preserve other parts during editing; after moving the solid, inspect its shadow and reflections especially. They should fit its new position.
The result is an image for further layout work
The finished file is a raster image made of pixels. Boxes do not turn it into a document with separate object, shadow and background layers. Keep the layout description, input material and selected illustration beside the cover project so you can revisit decisions.
Our poster studio gives you SVG with editable shapes and text. A generated illustration can provide material around which you build your own typography and composition. These two approaches let you retain control over the final layout.
Sources and further reading
The sources behind this article. Instructions and example scenarios are suggestions from our editorial team.
- Black Forest Labs: FLUX 3 Image — composition, editing and browser access (opens in a new tab)bfl.ai
- BFL documentation: boxes, reference images and output formats (opens in a new tab)docs.bfl.ai
- Topic inspiration: Promptowy, composition with boxes — October 1, 2026 (opens in a new tab)promptowy.com
- Cookie Analytics: open our SVG poster studio (opens in a new tab)qkianalytics.pl
- BFL documentation: box position, scale and limitations (opens in a new tab)docs.bfl.ai