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skills/media-processing/references/imagemagick-batch.md

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+# ImageMagick Batch Processing
+
+Complete guide to batch operations, mogrify command, parallel processing, and automation.
+
+## Mogrify Command
+
+### Basic Mogrify
+Modify files in-place (overwrites originals).
+
+```bash
+# Resize all JPEGs
+mogrify -resize 800x600 *.jpg
+
+# Convert format (creates new files)
+mogrify -format png *.jpg
+
+# Apply effect to all images
+mogrify -quality 85 -strip *.jpg
+```
+
+**Warning:** mogrify modifies files in-place. Always backup originals or use `-path` to output to different directory.
+
+### Output to Different Directory
+Preserve originals.
+
+```bash
+# Create output directory first
+mkdir output
+
+# Process to output directory
+mogrify -path ./output -resize 800x600 *.jpg
+
+# With format conversion
+mogrify -path ./optimized -format webp -quality 80 *.png
+```
+
+## Common Batch Operations
+
+### Resize All Images
+
+```bash
+# Resize to width 800
+mogrify -resize 800x *.jpg
+
+# Resize to height 600
+mogrify -resize x600 *.jpg
+
+# Fit within 800×600
+mogrify -resize 800x600 *.jpg
+
+# Resize to exact dimensions
+mogrify -resize 800x600! *.jpg
+
+# Only shrink, never enlarge
+mogrify -resize 800x600\> *.jpg
+```
+
+### Format Conversion
+
+```bash
+# PNG to JPEG
+mogrify -path ./jpg -format jpg -quality 85 *.png
+
+# JPEG to WebP
+mogrify -path ./webp -format webp -quality 80 *.jpg
+
+# Any format to PNG
+mogrify -path ./png -format png *.{jpg,gif,bmp}
+```
+
+### Optimize Images
+
+```bash
+# Strip metadata from all JPEGs
+mogrify -strip *.jpg
+
+# Optimize JPEGs for web
+mogrify -quality 85 -strip -interlace Plane *.jpg
+
+# Compress PNGs
+mogrify -quality 95 *.png
+
+# Combined optimization
+mogrify -quality 85 -strip -interlace Plane -sampling-factor 4:2:0 *.jpg
+```
+
+### Apply Effects
+
+```bash
+# Add watermark to all images
+mogrify -gravity southeast -draw "image over 10,10 0,0 'watermark.png'" *.jpg
+
+# Convert all to grayscale
+mogrify -colorspace Gray *.jpg
+
+# Apply sepia tone
+mogrify -sepia-tone 80% *.jpg
+
+# Sharpen all images
+mogrify -sharpen 0x1 *.jpg
+```
+
+### Thumbnail Generation
+
+```bash
+# Create square thumbnails
+mogrify -path ./thumbnails -resize 200x200^ -gravity center -extent 200x200 *.jpg
+
+# Create thumbnails with max dimension
+mogrify -path ./thumbs -thumbnail 300x300 *.jpg
+
+# Thumbnails with quality control
+mogrify -path ./thumbs -thumbnail 200x200 -quality 80 -strip *.jpg
+```
+
+## Shell Loops
+
+### Basic For Loop
+More control than mogrify.
+
+```bash
+# Resize with custom naming
+for img in *.jpg; do
+  magick "$img" -resize 800x600 "resized_$img"
+done
+
+# Process to subdirectory
+mkdir processed
+for img in *.jpg; do
+  magick "$img" -resize 1920x1080 "processed/$img"
+done
+```
+
+### Multiple Operations
+
+```bash
+# Complex processing pipeline
+for img in *.jpg; do
+  magick "$img" \
+    -resize 1920x1080^ \
+    -gravity center \
+    -crop 1920x1080+0+0 +repage \
+    -unsharp 0x1 \
+    -quality 85 -strip \
+    "processed_$img"
+done
+```
+
+### Format Conversion with Rename
+
+```bash
+# Convert PNG to JPEG with new names
+for img in *.png; do
+  magick "$img" -quality 90 "${img%.png}.jpg"
+done
+
+# Add prefix during conversion
+for img in *.jpg; do
+  magick "$img" -resize 800x "web_${img}"
+done
+```
+
+### Conditional Processing
+
+```bash
+# Only process large images
+for img in *.jpg; do
+  width=$(identify -format "%w" "$img")
+  if [ $width -gt 2000 ]; then
+    magick "$img" -resize 2000x "resized_$img"
+  fi
+done
+
+# Skip existing output files
+for img in *.jpg; do
+  output="output_$img"
+  if [ ! -f "$output" ]; then
+    magick "$img" -resize 800x "$output"
+  fi
+done
+```
+
+## Parallel Processing
+
+### GNU Parallel
+Process multiple images simultaneously.
+
+```bash
+# Install GNU Parallel
+# Ubuntu/Debian: sudo apt-get install parallel
+# macOS: brew install parallel
+
+# Basic parallel resize
+parallel magick {} -resize 800x600 resized_{} ::: *.jpg
+
+# Parallel with function
+resize_image() {
+  magick "$1" -resize 1920x1080 -quality 85 "processed_$1"
+}
+export -f resize_image
+parallel resize_image ::: *.jpg
+
+# Limit concurrent jobs
+parallel -j 4 magick {} -resize 800x {} ::: *.jpg
+
+# Progress indicator
+parallel --progress magick {} -resize 800x {} ::: *.jpg
+```
+
+### Xargs Parallel
+
+```bash
+# Using xargs for parallel processing
+ls *.jpg | xargs -I {} -P 4 magick {} -resize 800x processed_{}
+
+# With find
+find . -name "*.jpg" -print0 | \
+  xargs -0 -I {} -P 4 magick {} -resize 800x {}
+```
+
+## Advanced Batch Patterns
+
+### Recursive Processing
+
+```bash
+# Process all JPEGs in subdirectories
+find . -name "*.jpg" -exec magick {} -resize 800x {} \;
+
+# With output directory structure
+find . -name "*.jpg" -type f | while read img; do
+  outdir="output/$(dirname "$img")"
+  mkdir -p "$outdir"
+  magick "$img" -resize 800x "$outdir/$(basename "$img")"
+done
+```
+
+### Batch with Different Sizes
+
+```bash
+# Generate multiple sizes
+for size in 320 640 1024 1920; do
+  mkdir -p "output/${size}w"
+  for img in *.jpg; do
+    magick "$img" -resize ${size}x -quality 85 "output/${size}w/$img"
+  done
+done
+
+# Parallel version
+for size in 320 640 1024 1920; do
+  mkdir -p "output/${size}w"
+  parallel magick {} -resize ${size}x -quality 85 "output/${size}w/{}" ::: *.jpg
+done
+```
+
+### Responsive Image Set
+
+```bash
+# Create responsive image set with srcset
+mkdir -p responsive
+for img in *.jpg; do
+  base="${img%.jpg}"
+  for width in 320 640 1024 1920; do
+    magick "$img" -resize ${width}x -quality 85 \
+      "responsive/${base}-${width}w.jpg"
+  done
+done
+```
+
+### Watermark Batch
+
+```bash
+# Add watermark to all images
+for img in *.jpg; do
+  magick "$img" watermark.png \
+    -gravity southeast -geometry +10+10 \
+    -composite "watermarked_$img"
+done
+
+# Different watermark positions for portrait vs landscape
+for img in *.jpg; do
+  width=$(identify -format "%w" "$img")
+  height=$(identify -format "%h" "$img")
+
+  if [ $width -gt $height ]; then
+    # Landscape
+    magick "$img" watermark.png -gravity southeast -composite "marked_$img"
+  else
+    # Portrait
+    magick "$img" watermark.png -gravity south -composite "marked_$img"
+  fi
+done
+```
+
+## Error Handling
+
+### Check Before Processing
+
+```bash
+# Verify image before processing
+for img in *.jpg; do
+  if identify "$img" > /dev/null 2>&1; then
+    magick "$img" -resize 800x "processed_$img"
+  else
+    echo "Skipping corrupt image: $img"
+  fi
+done
+```
+
+### Log Processing
+
+```bash
+# Log successful and failed operations
+log_file="batch_process.log"
+error_log="errors.log"
+
+for img in *.jpg; do
+  if magick "$img" -resize 800x "output/$img" 2>> "$error_log"; then
+    echo "$(date): Processed $img" >> "$log_file"
+  else
+    echo "$(date): Failed $img" >> "$error_log"
+  fi
+done
+```
+
+### Dry Run Mode
+
+```bash
+# Test without modifying files
+dry_run=true
+
+for img in *.jpg; do
+  cmd="magick $img -resize 800x processed_$img"
+  if [ "$dry_run" = true ]; then
+    echo "Would run: $cmd"
+  else
+    eval $cmd
+  fi
+done
+```
+
+## Optimization Workflows
+
+### Web Publishing Pipeline
+
+```bash
+# Complete web optimization workflow
+mkdir -p web/{original,optimized,thumbnails}
+
+# Copy originals
+cp *.jpg web/original/
+
+# Create optimized versions
+mogrify -path web/optimized \
+  -resize 1920x1080\> \
+  -quality 85 \
+  -strip \
+  -interlace Plane \
+  web/original/*.jpg
+
+# Create thumbnails
+mogrify -path web/thumbnails \
+  -thumbnail 300x300 \
+  -quality 80 \
+  -strip \
+  web/original/*.jpg
+```
+
+### Archive to Web Conversion
+
+```bash
+# Convert high-res archives to web formats
+for img in archives/*.jpg; do
+  base=$(basename "$img" .jpg)
+
+  # Full size web version
+  magick "$img" -resize 2048x2048\> -quality 90 -strip "web/${base}.jpg"
+
+  # Thumbnail
+  magick "$img" -thumbnail 400x400 -quality 85 "web/${base}_thumb.jpg"
+
+  # WebP version
+  magick "$img" -resize 2048x2048\> -quality 85 "web/${base}.webp"
+done
+```
+
+### Print to Web Workflow
+
+```bash
+# Convert print-ready images to web
+for img in print/*.tif; do
+  base=$(basename "$img" .tif)
+
+  # Convert colorspace and optimize
+  magick "$img" \
+    -colorspace sRGB \
+    -resize 2000x2000\> \
+    -quality 90 \
+    -strip \
+    -interlace Plane \
+    "web/${base}.jpg"
+done
+```
+
+## Batch Reporting
+
+### Generate Report
+
+```bash
+# Create processing report
+report="batch_report.txt"
+echo "Batch Processing Report - $(date)" > "$report"
+echo "================================" >> "$report"
+
+total=0
+success=0
+failed=0
+
+for img in *.jpg; do
+  ((total++))
+  if magick "$img" -resize 800x "output/$img" 2>/dev/null; then
+    ((success++))
+    echo "✓ $img" >> "$report"
+  else
+    ((failed++))
+    echo "✗ $img" >> "$report"
+  fi
+done
+
+echo "" >> "$report"
+echo "Total: $total, Success: $success, Failed: $failed" >> "$report"
+```
+
+### Image Inventory
+
+```bash
+# Create inventory of images
+inventory="image_inventory.csv"
+echo "Filename,Width,Height,Format,Size,ColorSpace" > "$inventory"
+
+for img in *.{jpg,png,gif}; do
+  [ -f "$img" ] || continue
+  info=$(identify -format "%f,%w,%h,%m,%b,%[colorspace]" "$img")
+  echo "$info" >> "$inventory"
+done
+```
+
+## Performance Tips
+
+### Optimize Loop Performance
+
+```bash
+# Bad: Launch mogrify for each file
+for img in *.jpg; do
+  mogrify -resize 800x "$img"
+done
+
+# Good: Process all files in one mogrify call
+mogrify -resize 800x *.jpg
+
+# Best: Use parallel processing for complex operations
+parallel magick {} -resize 800x -quality 85 processed_{} ::: *.jpg
+```
+
+### Memory Management
+
+```bash
+# Limit memory for batch processing
+for img in *.jpg; do
+  magick -limit memory 2GB -limit map 4GB \
+    "$img" -resize 50% "output/$img"
+done
+```
+
+### Progress Tracking
+
+```bash
+# Show progress for long batch operations
+total=$(ls *.jpg | wc -l)
+current=0
+
+for img in *.jpg; do
+  ((current++))
+  echo "Processing $current/$total: $img"
+  magick "$img" -resize 800x "output/$img"
+done
+```
+
+## Automation Scripts
+
+### Complete Bash Script
+
+```bash
+#!/bin/bash
+
+# Configuration
+INPUT_DIR="./input"
+OUTPUT_DIR="./output"
+QUALITY=85
+MAX_WIDTH=1920
+THUMBNAIL_SIZE=300
+
+# Create output directories
+mkdir -p "$OUTPUT_DIR"/{full,thumbnails}
+
+# Process images
+echo "Processing images..."
+for img in "$INPUT_DIR"/*.{jpg,jpeg,png}; do
+  [ -f "$img" ] || continue
+
+  filename=$(basename "$img")
+  base="${filename%.*}"
+
+  # Full size
+  magick "$img" \
+    -resize ${MAX_WIDTH}x\> \
+    -quality $QUALITY \
+    -strip \
+    "$OUTPUT_DIR/full/${base}.jpg"
+
+  # Thumbnail
+  magick "$img" \
+    -thumbnail ${THUMBNAIL_SIZE}x${THUMBNAIL_SIZE} \
+    -quality 80 \
+    -strip \
+    "$OUTPUT_DIR/thumbnails/${base}_thumb.jpg"
+
+  echo "✓ $filename"
+done
+
+echo "Done!"
+```
+
+### Python Batch Script
+
+```python
+#!/usr/bin/env python3
+import os
+import subprocess
+from pathlib import Path
+
+INPUT_DIR = Path("./input")
+OUTPUT_DIR = Path("./output")
+SIZES = [320, 640, 1024, 1920]
+
+# Create output directories
+for size in SIZES:
+    (OUTPUT_DIR / f"{size}w").mkdir(parents=True, exist_ok=True)
+
+# Process images
+for img in INPUT_DIR.glob("*.jpg"):
+    for size in SIZES:
+        output = OUTPUT_DIR / f"{size}w" / img.name
+        subprocess.run([
+            "magick", str(img),
+            "-resize", f"{size}x",
+            "-quality", "85",
+            "-strip",
+            str(output)
+        ])
+        print(f"✓ {img.name} -> {size}w")
+```
+
+## Common Batch Recipes
+
+### Social Media Sizes
+
+```bash
+# Generate social media image sizes
+for img in *.jpg; do
+  base="${img%.jpg}"
+
+  # Instagram square (1080×1080)
+  magick "$img" -resize 1080x1080^ -gravity center -extent 1080x1080 "${base}_ig_square.jpg"
+
+  # Instagram portrait (1080×1350)
+  magick "$img" -resize 1080x1350^ -gravity center -extent 1080x1350 "${base}_ig_portrait.jpg"
+
+  # Facebook post (1200×630)
+  magick "$img" -resize 1200x630^ -gravity center -extent 1200x630 "${base}_fb_post.jpg"
+
+  # Twitter post (1200×675)
+  magick "$img" -resize 1200x675^ -gravity center -extent 1200x675 "${base}_tw_post.jpg"
+done
+```
+
+### Email Newsletter Images
+
+```bash
+# Optimize images for email
+mogrify -path ./email \
+  -resize 600x\> \
+  -quality 75 \
+  -strip \
+  -interlace Plane \
+  *.jpg
+```
+
+### Backup and Archive
+
+```bash
+# Create web versions and keep originals
+mkdir -p {originals,web}
+
+# Move originals
+mv *.jpg originals/
+
+# Create optimized copies
+for img in originals/*.jpg; do
+  base=$(basename "$img")
+  magick "$img" -resize 2000x2000\> -quality 85 -strip "web/$base"
+done
+```