EPUB Optimizer Pro

Optimize EPUB images for e-ink displays using MozJPEG WASM.

Features

• True Grayscale (Y-only) - No Cb/Cr chroma channels
• Baseline JPEG - Maximum compatibility
• Optimized Huffman Tables - Better compression
• Trellis Quantization - Higher quality at same size
• 100% Client-side - No server uploads

MozJPEG Encoder Settings

// Using wasm-mozjpeg from 3bl3gamer
mozJpeg.cinfo_set_out_color_space(JCS_GRAYSCALE);  // Y-only, NO chroma
mozJpeg.cinfo_set_optimize_coding(true);            // Optimized Huffman
mozJpeg.cinfo_disable_progression();                // Baseline JPEG
mozJpeg.cinfo_set_trellis(10, true, true, true);    // Trellis quantization
mozJpeg.cinfo_set_quant_table(3);                   // Best quality table

Local Development

npm install
npm run dev

Build for Production

npm run build

Output goes to dist/ folder.

Deploy to Cloudflare Pages

Option 1: Connect Git Repository

1. Push to GitHub/GitLab
2. Go to Cloudflare Pages
3. Create new project → Connect repository
4. Build settings:
   • Build command: npm run build
   • Build output directory: dist

Option 2: Wrangler CLI

npm run build
npx wrangler pages deploy dist

Option 3: Direct Upload

Build locally, then drag dist/ folder to Cloudflare Pages dashboard.

Project Structure

epub-optimizer-pro/
├── index.html
├── package.json
├── vite.config.js
└── src/
    ├── main.js
    ├── mozjpeg-encoder.js   # wasm-mozjpeg wrapper
    └── style.css

MozJPEG Package

Uses wasm-mozjpeg:

• 34 KiB gzipped
• Grayscale, RGB, YCbCr output support
• Full MozJPEG control

Image Processing Modes

Mode	Badge	Description
Normal	•	Scale to 480×800, grayscale
H-Split	H	Rotate + split wide images
V-Split	V	Split tall images vertically
Rotate	R	Rotate landscape 90°

Why This Setup?

Feature	Canvas toBlob	MozJPEG WASM
Colorspace	RGB (3 ch)	Grayscale (1 ch)
Huffman	Standard	Optimized
Trellis	❌	✅
Progressive	❌	Disabled (baseline)
File size	Baseline	~25-35% smaller

License

MIT