image-prompting

# Image Prompting Best Practices When helping users generate or edit images with nanobanana, apply these guidelines. ## Prompt Structure for Generation A strong image prompt follows this pattern: **[Subject] + [Style] + [Composition] + [Lighting/Mood] + [Details]** Example: "A cozy coffee shop interior, watercolor illustration style, wide angle view, warm golden lighting, with plants on shelves and a cat sleeping on a chair" ## Model Selection Guide nanobanana supports three Gemini models via the `NANOBANANA_MODEL` env var: | Model | Best For | |-------|----------| | `gemini-2.5-flash-image` (default) | Fast generation, prototyping, high-volume work | | `gemini-3-pro-image-preview` | Complex prompts, text rendering in images, high quality | | `gemini-3.1-flash-image-preview` | Latest features, advanced capabilities | Recommend model changes when appropriate: - User needs text in the image -> suggest Pro - User is iterating rapidly -> stick with Flash (default) - User wants highest quality for final output -> suggest Pro ## Editing Best Practices When using `edit_image` or `continue_editing`: - Be specific about what to change: "Make the sky more orange" not "improve the colors" - Reference specific areas: "Add a tree in the bottom-left corner" - For style transfer, use reference images via the `referenceImages` parameter - Each edit creates a new file -- the original is always preserved ## Constraints - Prompts over 10,000 characters will be rejected - Image files must be under 20MB - Supported input formats: JPEG, PNG, WebP, GIF - Output is always PNG - File paths must resolve within `$HOME` or `$TMPDIR` (security constraint) - Images are saved to `~/nanobanana-images/` ## Iterative Workflow The most effective image workflow is: 1. Generate a base image with a detailed prompt 2. Use `continue_editing` for incremental refinements 3. Each iteration should address ONE specific change 4. If the result diverges too far, start fresh with `generate_image`