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bananarama

bananarama generates presentation images using Google Gemini. Define your images in a YAML configuration file with support for reference images and style defaults. Using gemini to generate slide images usually means a tedious loop of copying prompts into a web UI, downloading images, tweaking, and repeating. bananarama makes this process reproducible: your prompts live in version-controlled YAML, and regenerating every image is a single function call. No more copy-paste, no more losing track of which prompt produced which image. It also generates all images in parallel, making it wicked fast to generate full deck of images.

Installation

You can install the development version of bananarama from GitHub:

# install.packages("pak")
pak::pak("hadley/bananarama")

Usage

Create a bananarama.yaml file that describes the images you want to generate:

defaults:
  style: >
    Flat vector editorial illustration with a muted, desaturated
    color palette. Mid-century modern aesthetic. Calm and approachable.
  aspect-ratio: 16:9

images:
  - name: robot-factory
    description: >
      Draw a picture of [hadley] overseeing a factory full of robots.
      The robots should be typing at computers.

Reference images like [hadley] are matched to image files (e.g. hadley.png) in the same directory as the YAML file.

Then generate the images with:

bananarama::bananarama("path/to/bananarama.yaml")

Images that already exist are skipped unless you pass force = TRUE.

YAML configuration

defaults

  • style: Style prompt appended to every image description. Use this to ensure a consistent style across all slides.
  • description: Default description; not usually needed unless you want to experiment with styles.
  • aspect-ratio: One of "1:1", "3:2", "16:9", etc. Default: "16:9".
  • resolution: One of "1K", "2K", "4K". Default: "1K".
  • n: Number of variants to generate per image. Default: 1.
  • model: Gemini model to use. Default: "gemini-3.1-flash-image-preview" (aka nano banana2).
  • force: If true, regenerate images even if they already exist. Default: false.
  • seed: Integer seed for the random number generator. Makes output more (but not perfectly) deterministic.

output-dir

Output directory for generated images, relative to the YAML file. Defaults to a directory with the same name as the YAML file (e.g. bananarama.yaml outputs to bananarama/).

images

Each image has:

  • name (required): Used as the output filename ({name}.png).
  • description (required, unless a default is set): Prompt for image generation. Use [name] to reference images in the same directory.
  • n: Number of variants to generate. Output files are named {name}-1.png, {name}-2.png, etc. Default: 1.
  • style, aspect-ratio, resolution, model, force, seed: Per-image overrides of the defaults.