concept-to-image

Concept to Image

Creates polished visuals from concepts using HTML/CSS/SVG as a refineable intermediate, then exports to PNG or SVG.

Reference Files

File	Purpose
references/design-guide.md	Design patterns, anti-patterns, color palettes, typography choices, layout examples
scripts/render_to_image.py	Playwright-based export script — takes HTML in, PNG or SVG out
assets/template.html	Base HTML template with .canvas container and CSS custom properties pre-configured

Why HTML as intermediate

HTML is the refineable layer between idea and image. Unlike direct canvas rendering, the user can see the HTML artifact, request changes ("make the title bigger", "swap the colors", "add a third column"), and only export once satisfied. This makes the workflow iterative and controllable.

Workflow

Concept → HTML artifact (view + refine) → PNG or SVG export

1. Interpret the user's concept — determine what kind of visual best fits (diagram, infographic, card, chart, etc.)
2. Design a self-contained HTML file using inline CSS and inline SVG — zero external dependencies
3. Present the HTML as an artifact so the user can preview and request refinements
4. Iterate on the HTML based on user feedback (colors, layout, content, sizing)
5. Export to PNG and/or SVG when the user is satisfied, using scripts/render_to_image.py

Step 1: Interpret the concept

Determine the best visual format:

User intent	Visual format	Approach
Explain a process/flow	Flowchart or pipeline diagram	SVG paths + boxes
Compare items	Side-by-side or matrix	CSS Grid
Show hierarchy	Tree or layered diagram	Nested containers + SVG connectors
Present data	Chart or infographic	SVG shapes + data labels
Social/marketing graphic	Card or poster	Typography-forward HTML/CSS
Icon, logo, badge	Compact symbol	Pure SVG
Educational concept	Annotated diagram	SVG + positioned labels

Step 2: Design the HTML

Read references/design-guide.md for detailed design patterns and anti-patterns.

Core rules:

• Single file, self-contained: All CSS inline in <style>, all graphics as inline <svg>. No external resources.
• Fixed viewport: Set explicit width and height on the root container matching the intended export size. This is critical — Playwright screenshots the element at this exact size.
• Anti-AI-slop: Avoid centered-everything layouts, purple gradients, uniform rounded corners, and Inter/system font defaults. See design guide for alternatives.
• SVG-first for shapes: Use inline SVG for icons, connectors, shapes, and any element that should scale cleanly. CSS for layout and typography.
• Color with intention: 3-4 hues max + neutrals. Define as CSS custom properties. Every color encodes meaning.
• Start from the template: Use assets/template.html as the base structure.

Sizing guidelines

Use case	Recommended size
Social media graphic	1200×630
Infographic (portrait)	800×1200
Presentation slide	1920×1080
Square post	1080×1080
Icon/badge	256×256 or 512×512
Wide diagram	1600×900

Set the .canvas container to the chosen size. The export script captures this element.

Step 3: Present and iterate

Present the HTML file to the user. They'll see it rendered as an artifact. Common refinement requests:

• Color/theme changes → update CSS custom properties
• Layout adjustments → modify grid/flexbox
• Content changes → edit text/SVG elements
• Size changes → update .canvas dimensions

Each iteration is a quick HTML edit, not a full re-render. This is the key advantage over direct image generation.

Step 4: Export to image

Once the user is satisfied, run the export script:

python3 scripts/render_to_image.py <input.html> <output.png|.svg> [--width 1200] [--height 630] [--scale 2] [--selector ".canvas"]

Parameters

Param	Default	Description
input	(required)	Path to HTML file
output	(required)	Output path. Extension determines format (.png or .svg)
--width	auto	Viewport width (overrides HTML-defined size)
--height	auto	Viewport height (overrides HTML-defined size)
--scale	2	Device scale factor for PNG (2 = retina quality)
--selector	.canvas	CSS selector for the element to capture
--full-page	false	Capture the full page instead of a specific element

PNG export

Uses Playwright to launch headless Chromium and screenshot the .canvas element at the specified scale factor. Scale 2 produces retina-quality output (e.g., 1200×630 CSS pixels → 2400×1260 PNG ≈ 3.02 MP).

Opus 4.7 feedback loop: Retina-scale exports (e.g., 2400×1260) fit within Opus 4.7's ~3.75 MP vision ceiling, so you can feed the rendered PNG back to the model for iterate-by-critique loops without downsampling. Under Opus 4.6 these outputs would have been downscaled on ingestion.

SVG export

Two strategies, chosen automatically:

1. SVG-native content: If the .canvas element contains a single root <svg>, extracts it directly as a clean SVG file. This produces a true vector SVG.
2. HTML-based content: If the content is CSS/HTML-heavy, falls back to PNG export with a note that true SVG requires SVG-native design. The script will warn and suggest redesigning with SVG elements if vector output is needed.

Delivering the output

Present the output file to the user. Always deliver both the HTML (for future editing) and the image (final output).

Error Handling

Error	Cause	Resolution
playwright not found	Playwright package not installed	Run npx playwright install chromium or pip install playwright && playwright install chromium
Browser launch failure	Headless Chromium fails to start	Verify --headless mode is supported; check available memory (Chromium needs ~200 MB)
.canvas selector not found	HTML does not contain an element matching .canvas	Verify assets/template.html was used as the base; check the root container has class="canvas"
Render timeout	Complex HTML takes too long to render before screenshot	Increase the timeout via --timeout flag in the script, or simplify the HTML (reduce DOM depth, inline fewer SVGs)
SVG export falls back to PNG	.canvas element contains HTML/CSS content, not a root SVG	See SVG export section; redesign with a single root <svg> if vector output is required

Limitations

• Playwright + Chromium required — the export script cannot run without a working Chromium installation.
• macOS and Linux only for headless browser export. Windows Subsystem for Linux works; native Windows Playwright may require separate setup.
• SVG export is best-effort — complex HTML/CSS layouts fall back to PNG. True vector SVG requires a single root <svg> as the .canvas child.
• Max viewport 4096×4096 — Chromium refuses screenshots larger than this. Use --scale to achieve higher effective resolution within this limit.
• No animation support — exported images are static snapshots. CSS animations and JavaScript-driven transitions are frozen at their initial state.

Output Example

After a successful export, the script prints the output path and file stats:

Exported: concept-diagram.png
  Size:       2400 × 1260 px  (2× scale from 1200 × 630 canvas)
  File size:  ~180 KB
  Format:     PNG (RGBA)

Filename pattern follows whatever was passed as the output argument. Typical file sizes:

• Simple diagrams (text + shapes): 80–200 KB
• Dense infographics with gradients: 300–600 KB
• Full 1920×1080 at 2× scale: 500 KB–1.5 MB

Design anti-patterns to avoid

These produce generic "AI-generated" looking output:

• Centered everything with equal spacing
• Purple/blue gradient backgrounds
• Uniform border-radius on all elements
• Generic icon libraries (use custom inline SVG)
• System font stack without typographic intention
• Drop shadows on everything
• Low information density (too much whitespace)

Font handling

Since this environment has limited font access, use web-safe font stacks with intentional fallbacks:

• Technical/mono: 'Courier New', 'Consolas', monospace
• Clean sans: 'Helvetica Neue', 'Arial', sans-serif
• Editorial serif: 'Georgia', 'Times New Roman', serif
• Display: Use SVG text with custom paths for display typography when needed