imagemagick-conversion

# ImageMagick Image Conversion **Project:** Project-independent **Gitignored:** Yes ## Trigger Use this skill when users request image manipulation tasks including: - Converting between image formats (PNG, JPEG, WebP, GIF, TIFF, etc.) - Resizing images (dimensions, percentages, aspect ratios) - Batch processing multiple images - Adjusting image quality and compression - Creating thumbnails - Basic image transformations (rotate, flip, crop) ## Overview ImageMagick is a powerful command-line tool for image processing. This skill provides guidance for using the `magick` command to perform common image conversion and manipulation tasks. **Key Command Pattern:** ```bash magick input-file [options] output-file ``` ## Common Use Cases ### Format Conversion **Basic format conversion:** ```bash magick image.jpg image.png magick photo.png photo.webp ``` **Batch convert all JPEGs to PNG:** ```bash magick mogrify -format png *.jpg ``` **Convert with specific output directory:** ```bash mkdir -p output magick mogrify -format webp -path output/ *.jpg ``` ### Resizing Images **Resize by percentage:** ```bash magick image.jpg -resize 50% output.jpg ``` **Resize to specific width (maintain aspect ratio):** ```bash magick image.jpg -resize 800x output.jpg ``` **Resize to specific height (maintain aspect ratio):** ```bash magick image.jpg -resize x600 output.jpg ``` **Resize to fit within dimensions (maintain aspect ratio):** ```bash magick image.jpg -resize 800x600 output.jpg ``` **Resize to exact dimensions (ignore aspect ratio):** ```bash magick image.jpg -resize 800x600! output.jpg ``` **Resize only if larger:** ```bash magick image.jpg -resize '800x600>' output.jpg ``` **Resize only if smaller:** ```bash magick image.jpg -resize '800x600<' output.jpg ``` ### Quality and Compression **Set JPEG quality (1-100, default 92):** ```bash magick image.jpg -quality 85 output.jpg ``` **Optimize PNG compression:** ```bash magick image.png -quality 95 output.png ``` **Create high-quality WebP:** ```bash magick image.jpg -quality 90 output.webp ``` ### Thumbnails **Generate thumbnail (fast, lower quality):** ```bash magick image.jpg -thumbnail 200x200 thumb.jpg ``` **Generate thumbnail with padding:** ```bash magick image.jpg -thumbnail 200x200 -background white -gravity center -extent 200x200 thumb.jpg ``` ### Batch Operations **Resize all images in directory:** ```bash magick mogrify -resize 800x600 -path resized/ *.jpg ``` **Convert and resize in one operation:** ```bash magick mogrify -resize 1200x -format webp -quality 85 -path output/ *.jpg ``` **Process specific file types:** ```bash magick mogrify -resize 50% -path smaller/ *.{jpg,png,gif} ``` ### Image Information **Display image information:** ```bash magick identify image.jpg ``` **Detailed image information:** ```bash magick identify -verbose image.jpg ``` ### Advanced Transformations **Rotate image:** ```bash magick image.jpg -rotate 90 rotated.jpg ``` **Flip horizontally:** ```bash magick image.jpg -flop flipped.jpg ``` **Flip vertically:** ```bash magick image.jpg -flip flipped.jpg ``` **Crop to specific region:** ```bash magick image.jpg -crop 800x600+100+100 cropped.jpg ``` **Auto-orient based on EXIF:** ```bash magick image.jpg -auto-orient output.jpg ``` **Strip metadata (reduce file size):** ```bash magick image.jpg -strip output.jpg ``` ## Important Notes ### mogrify vs convert - **`magick mogrify`**: Modifies files in-place or writes to specified path - Use `-path` option to preserve originals - Efficient for batch operations - **`magick convert`** (or just `magick`): Creates new files - Always preserves original - Better for single-file operations ### Performance Tips 1. **Use `-thumbnail` for thumbnails**: Faster than `-resize` for small previews 2. **Use `-strip` to remove metadata**: Reduces file size significantly 3. **Batch operations**: Process multiple files in one `mogrify` command 4. **Quality settings**: 85-90 is usually optimal for JPEG (balances size/quality) ### Format Recommendations - **JPEG**: Photos, complex images with gradients (lossy) - **PNG**: Screenshots, graphics with transparency (lossless) - **WebP**: Modern format, excellent compression (lossy or lossless) - **GIF**: Simple animations, limited colors - **TIFF**: Archival, high-quality storage ## Safety Considerations **Always test commands on copies first:** ```bash # Create test directory mkdir -p test-output # Test on single file magick original.jpg -resize 50% test-output/test.jpg # Verify result before batch processing ``` **Use `-path` with mogrify to preserve originals:** ```bash # This preserves originals in current directory magick mogrify -resize 800x -path resized/ *.jpg ``` **Quote wildcards in shell:** ```bash # Prevents premature shell expansion magick mogrify -resize '800x600>' -path output/ '*.jpg' ``` ## Common Patterns ### Web Optimization Workflow ```bash # Create optimized versions for web mkdir -p web-optimized # Convert to WebP with quality 85, resize to max 1920px width magick mogrify -resize 1920x -quality 85 -format webp -path web-optimized/ *.jpg # Strip metadata to reduce size magick mogrify -strip web-optimized/*.webp ``` ### Thumbnail Generation ```bash # Create thumbnail directory mkdir -p thumbnails # Generate 300x300 thumbnails with white padding for img in *.jpg; do magick "$img" -thumbnail 300x300 -background white -gravity center -extent 300x300 "thumbnails/${img%.jpg}_thumb.jpg" done ``` ### Multi-Format Export ```bash # Export to multiple formats for compatibility mkdir -p exports/{png,webp,jpg} for img in source/*.png; do name=$(basename "$img" .png) magick "$img" -quality 90 "exports/png/$name.png" magick "$img" -quality 85 "exports/webp/$name.webp" magick "$img" -quality 85 "exports/jpg/$name.jpg" done ``` ## Troubleshooting **Check ImageMagick version:** ```bash magick -version ``` **Verify supported formats:** ```bash magick identify -list format ``` **Test command on single file first:** ```bash # Always test before batch operations magick test-image.jpg -resize 50% test-output.jpg ``` ## When to Use This Skill **✓ Use this skill for:** - Format conversions between standard image types - Resizing operations (dimensions, percentages) - Quality adjustments and compression - Batch processing workflows - Generating thumbnails or previews - Basic transformations (rotate, crop, flip) **✗ Don't use this skill for:** - Advanced photo editing (use GIMP, Photoshop) - Complex filters or effects (consider dedicated tools) - Video processing (use FFmpeg) - Vector graphics (use Inkscape, Illustrator) ## Integration with Workflows This skill complements other development workflows: - **Web development**: Optimize images for deployment - **Documentation**: Generate screenshots and diagrams - **CI/CD**: Automate image processing in pipelines - **Content creation**: Prepare images for various platforms The `magick` command is typically available via Homebrew (`brew install imagemagick`) or system package managers.