Media Processing Skill

Process images using ImageMagick command-line tools for conversion, optimization, streaming, and manipulation tasks.

When to Use This Skill

Use when:

• Converting media formats (video, audio, images)

• Encoding video with codecs (H.264, H.265, VP9, AV1)

• Processing images (resize, crop, effects, watermarks)

• Extracting audio from video

• Creating streaming manifests (HLS/DASH)

• Generating thumbnails and previews

• Batch processing media files

• Optimizing file sizes and quality

• Applying filters and effects

• Creating composite images or videos

Tool Selection Guide

ImageMagick: Image Processing

Use ImageMagick for:

• Image format conversion (PNG, JPEG, WebP, GIF)

• Resizing, cropping, transformations

• Batch image processing (mogrify)

• Visual effects (blur, sharpen, sepia)

• Text overlays and watermarks

• Image composition and montages

• Color adjustments, filters

• Thumbnail generation

Decision Matrix

Task Tool Why

Image resize ImageMagick Optimized for still images

Batch images ImageMagick mogrify for in-place edits

Image effects ImageMagick Rich filter library

Installation

macOS

brew install ffmpeg imagemagick

Ubuntu/Debian

sudo apt-get install ffmpeg imagemagick

Windows

Using winget

winget install ffmpeg winget install ImageMagick.ImageMagick

Or download binaries

FFmpeg: https://ffmpeg.org/download.html

ImageMagick: https://imagemagick.org/script/download.php

Verify Installation

magick -version

or

convert -version

Quick Start Examples

Image Processing

Convert format

magick input.png output.jpg

Resize maintaining aspect ratio

magick input.jpg -resize 800x600 output.jpg

Create square thumbnail

magick input.jpg -resize 200x200^ -gravity center -extent 200x200 thumb.jpg

Batch Image Resize

Resize all JPEGs to 800px width

mogrify -resize 800x -quality 85 *.jpg

Output to separate directory

mogrify -path ./output -resize 800x600 *.jpg

Image Watermark

Add watermark to corner

magick input.jpg watermark.png -gravity southeast
-geometry +10+10 -composite output.jpg

Common Workflows

Create Responsive Images

Generate multiple sizes

for size in 320 640 1024 1920; do magick input.jpg -resize ${size}x -quality 85 "output-${size}w.jpg" done

Batch Image Optimization

Convert PNG to optimized JPEG

mogrify -path ./optimized -format jpg -quality 85 -strip *.png

Image Blur Effect

Gaussian blur

magick input.jpg -gaussian-blur 0x8 output.jpg

Advanced Techniques

Complex Image Pipeline

Resize, crop, border, adjust

magick input.jpg
-resize 1000x1000^
-gravity center
-crop 1000x1000+0+0 +repage
-bordercolor black -border 5x5
-brightness-contrast 5x10
-quality 90
output.jpg

Animated GIF from Images

Create with delay

magick -delay 100 -loop 0 frame*.png animated.gif

Optimize size

magick animated.gif -fuzz 5% -layers Optimize optimized.gif

Media Analysis

Image Information

Basic info

identify image.jpg

Detailed format

identify -verbose image.jpg

Custom format

identify -format "%f: %wx%h %b\n" image.jpg

Performance Tips

• Copy streams when possible - Avoid re-encoding with -c copy

• Appropriate presets - Balance speed vs compression

• Batch with mogrify - In-place image processing

• Strip metadata - Reduce file size with -strip

• Progressive JPEG - Better web loading with -interlace Plane

• Limit memory - Prevent crashes on large batches

• Test on samples - Verify settings before batch

• Parallel processing - Use GNU Parallel for multiple files

Reference Documentation

Detailed guides in references/ :

• imagemagick-editing.md - Format conversion, effects, transformations

• imagemagick-batch.md - Batch processing, mogrify, parallel operations

Common Parameters

ImageMagick Geometry

• 800x600

• Fit within (maintains aspect)

• 800x600!

• Force exact size

• 800x600^

• Fill (may crop)

• 800x

• Width only

• x600

• Height only

• 50%

• Scale percentage

Troubleshooting

ImageMagick "not authorized"

Edit policy file

sudo nano /etc/ImageMagick-7/policy.xml

Change <policy domain="coder" rights="none" pattern="PDF" />

to <policy domain="coder" rights="read|write" pattern="PDF" />

Memory errors

Limit memory usage

magick -limit memory 2GB -limit map 4GB input.jpg output.jpg

Resources

• ImageMagick: https://imagemagick.org/

• ImageMagick Usage: https://imagemagick.org/Usage/