picture（picture 效率）

Image Generation

Generate AI images using Google Imagen via the Gemini API.

When to Use

• Presentation images (hero visuals, section dividers)
• Conceptual illustrations (visual metaphors, abstract concepts)
• Photo-realistic images (product mockups, scenarios)
• Visual explanations that benefit from AI generation

When NOT to Use

• Precise diagrams or charts — use diagramming skill (editable SVG, exact data)
• Screenshots — use screenshot skill
• Simple icons — often faster to find stock or use emoji

Overlap with diagramming: There's fuzzy boundary. A "chart for a presentation" could go either way:

• Need precise data, editability → diagramming
• Need striking visual punch → image-generation
• Use judgement; ask if unclear.

Workflow

1. Understand the Need

Clarify with user:

• Purpose — presentation, concept illustration, visual metaphor?
• Style — photorealistic, illustration, abstract?
• Brand — does it need ITV styling? (if so, read itv-styling skill)

2. Draft with Flash

Use the fast model for initial iterations:

${CLAUDE_SKILL_DIR}/imagen.sh "prompt" --model gemini-2.5-flash-image

3. Review and Refine

Open the image, assess, iterate:

# Edit mode: refine previous output
${CLAUDE_SKILL_DIR}/imagen.sh "make it warmer, add more contrast" --input ./images/previous.png

4. Final Render with Pro

For client-facing or final deliverables:

${CLAUDE_SKILL_DIR}/imagen.sh "prompt" --model gemini-3-pro-image-preview

Command Reference

# Basic generation
imagen.sh "prompt" [--output ./images] [--model MODEL]

# Edit existing image
imagen.sh "refinement prompt" --input previous.png

# Models
--model gemini-2.5-flash-image     # Fast, cheap (default)
--model gemini-3-pro-image-preview # Higher quality
--model imagen-4.0-generate-preview-06-06  # Imagen 4

Output: Saves to ./images/ with timestamped filename, prints path.

Prompting Framework

Based on Max Woolf's Nano Banana research.

Structure

[Specific object description with exact requirements in CAPS]

Aspects that MUST be followed EXACTLY:
- [Compositional rule 1]
- [Compositional rule 2]

[Publication/camera details for style elevation]

Do not include [unwanted elements].

Key Techniques

Example Prompt

A professional headshot of a confident business executive.

Aspects that MUST be followed EXACTLY:
- Shot from shoulders up, rule of thirds composition
- Neutral background with soft gradient #E8E8E8 to #FFFFFF
- Natural 3PM diffuse lighting from left
- Sharp focus on eyes, slight bokeh on background

Pulitzer Prize-winning portrait, Canon EOS R5, 85mm f/1.4.

Do not include any text, logos, or watermarks.

Composing with Brand Skills

With itv-styling

When creating ITV-branded images:

1. Read itv-styling for color palette and principles
2. Bake brand constraints into prompt:

Corporate presentation image for ITV.

Aspects that MUST be followed EXACTLY:
- Dark background #0F2323 (ITV dark green)
- Accent elements in #E8E557 (ITV yellow) or #4ECDC4 (ITV teal)
- Clean, modern, professional aesthetic
- No busy patterns or off-brand colors

Professional corporate photography style.

With diagramming

For hybrid needs (visual + precise data):

• Generate AI background/illustration with image-generation
• Overlay precise elements with diagramming
• Composite manually if needed

Limitations

Output Location

Images save to ./images/ in the project directory:

• Created on first use
• Timestamped filenames for uniqueness
• Stays with project for easy reference

Anti-Patterns

See Also

• references/prompting.md — Extended prompting reference
• diagramming skill — For precise diagrams and charts
• itv-styling skill — For brand-constrained outputs