Image Processing

Process images for web development. Generate a Pillow script adapted to the user's environment and specific needs.

Prerequisites

Pillow is usually pre-installed. If not:

pip install Pillow

If Pillow is unavailable, adapt using alternatives:

Alternative	Platform	Install	Capabilities
sips	macOS (built-in)	None	Resize, convert (no trim/OG)
sharp	Node.js	npm install sharp	Full feature set
ffmpeg	Cross-platform	brew install ffmpeg	Resize, convert

Capabilities

Generate a Python script using Pillow for any of these operations. See references/pillow-patterns.md for implementation patterns, especially RGBA-to-JPG compositing and cross-platform font discovery.

Resize

Scale to specific dimensions or by width/height (maintain aspect ratio if only one given). Use Image.LANCZOS for high-quality downscaling.

Convert Format

Convert between PNG, JPG, WebP. Handle RGBA-to-JPG by compositing onto white background. Apply format-specific quality settings (WebP: 85, JPG: 90, PNG: optimize).

Trim Whitespace

Auto-crop surrounding whitespace from logos and icons. Convert to RGBA first, then use getbbox() to find content bounds.

Thumbnail

Fit within max dimensions while maintaining aspect ratio. Use img.thumbnail((size, size), Image.LANCZOS).

Optimise for Web

Resize + compress in one step. Convert to WebP for best compression. Typical settings: width 1920, quality 85.

OG Card (1200x630)

Generate Open Graph card with title/subtitle overlay on a background image or solid colour. Apply semi-transparent overlay for text readability. Centre text horizontally.

Common Workflows

Logo Cleanup (client-supplied JPG with white background)

1. Trim whitespace
2. Convert to PNG (for transparency)
3. Create favicon-sized version (thumbnail at 512px)

Prepare Hero Image for Production

Resize to max width 1920, convert to WebP, compress at quality 85.

Batch Process

For multiple images, generate a single script that loops over all files rather than processing one at a time.

Pipeline with Gemini Image Gen

Generate images with the gemini-image-gen skill, then process them:

1. Generate with Gemini (raw PNG output)
2. User picks favourite
3. Optimise: resize to target width, convert to WebP, compress

Output Format Guide

Use case	Format	Why
Photos, hero images	WebP	Best compression, wide browser support
Logos, icons (need transparency)	PNG	Lossless, supports alpha
Fallback for older browsers	JPG	Universal support
Thumbnails	WebP or JPG	Small file size priority
OG cards	PNG	Social platforms handle PNG best

Reference Files

When	Read
Implementing any Pillow operation	references/pillow-patterns.md