processing-images

What this skill does

# Image Processing Tools

This container has a rich image processing toolkit. Before writing any image code, scan this inventory to pick the best tool for the job — don't default to Pillow for everything.

## Tool Selection by Task

### Format Conversion & Batch Operations
**ImageMagick `convert`** is the default choice. Handles 260+ formats, single command, no code needed.
```
convert input.png output.webp
convert input.png -quality 85 output.jpg
mogrify -format webp *.png          # batch in-place
```
For animated formats (GIF↔WebP↔APNG, video↔frames), prefer **ffmpeg**.

### Resize, Crop, Thumbnails
**ImageMagick** for CLI one-liners. **Pillow** when already in Python pipeline.
```
convert input.jpg -resize 800x600 output.jpg          # fit within box
convert input.jpg -resize 800x600^ -gravity center -extent 800x600 output.jpg  # fill+crop
convert input.jpg -thumbnail 200x200^ -gravity center -extent 200x200 thumb.jpg
```
IM supports 30+ resize filters: `-filter Lanczos` (sharp downscale), `-filter Mitchell` (balanced), `-filter Point` (nearest-neighbor/pixel art).

### Compositing & Overlays
**ImageMagick `composite`** or `convert` with `-composite`. Supports all Porter-Duff modes.
```
composite -gravity southeast watermark.png photo.jpg output.jpg
convert base.png overlay.png -gravity center -composite result.png
```
For complex multi-layer work or programmatic positioning, use **Pillow** (`Image.paste`, `Image.alpha_composite`).

### Montages, Collages, Contact Sheets
**ImageMagick `montage`** — purpose-built for grid layouts.
```
montage *.jpg -geometry 200x200+5+5 -tile 4x3 sheet.jpg
montage *.png -label '%f' -geometry +4+4 catalog.png
```

### Animated GIFs & Frame Sequences
**ImageMagick** for simple GIF assembly. **ffmpeg** for anything involving timing control, video sources, or optimization.
```
convert -delay 10 -loop 0 frame_*.png animation.gif        # IM
ffmpeg -framerate 10 -i frame_%03d.png -vf palettegen palette.png && \
ffmpeg -framerate 10 -i frame_%03d.png -i palette.png -lavfi paletteuse output.gif  # optimized
```
**imageio** is convenient for frame-sequence GIFs from Python arrays.

### Image Analysis & Measurement
**`identify`** for quick metadata and stats. **OpenCV** for structural analysis. **scikit-image** for scientific measurement.
```
identify -verbose image.png          # full metadata dump
identify -format '%wx%h %[colorspace] %[depth]bit' image.png   # targeted
```
- **OpenCV** (`cv2`): histograms, contour detection, template matching, edge detection, color distribution
- **scikit-image** (`skimage`): region properties, morphology, thresholding (Otsu, adaptive), feature detection (SIFT via OpenCV, ORB), SSIM comparison
- **scipy.ndimage**: convolution, interpolation, labeling connected components

### Image Comparison & Diffing
**ImageMagick `compare`** produces visual diffs directly.
```
compare image1.png image2.png diff.png
compare -metric RMSE image1.png image2.png null: 2>&1   # numeric similarity
```
For structural similarity: `skimage.metrics.structural_similarity` (SSIM).

### Color Operations
**ImageMagick** handles color space conversion, channel manipulation, color quantization.
```
convert input.jpg -colorspace Gray output.jpg
convert input.png -colors 16 reduced.png           # quantize
convert input.jpg -modulate 110,130,100 output.jpg  # brightness,saturation,hue
convert input.png -channel R -separate red_channel.png
```
For programmatic color analysis (dominant colors, palettes): **OpenCV** k-means on pixel arrays, or **Pillow** `getcolors()`.

### Effects & Filters
**ImageMagick** has extensive built-in effects:
```
convert in.png -blur 0x3 out.png              # Gaussian blur
convert in.png -sharpen 0x1 out.png
convert in.png -shadow 60x4+2+2 out.png       # drop shadow
convert in.png -vignette 0x40 out.png
convert in.png -sketch 0x10+120 out.png
convert in.png -charcoal 2 out.png
convert in.png -edge 1 out.png
convert in.png -emboss 1 out.png
convert in.png \( +clone -background black -shadow 60x4+0+0 \) +swap -background none -layers merge +repage rounded.png
```
For advanced/custom convolution kernels: **scipy.ndimage** or **OpenCV**.

### Metadata & EXIF
**`identify -verbose`** reads all metadata. **Pillow** reads/writes EXIF programmatically.
```
identify -verbose image.jpg | grep -A20 'Properties:'
```
```python
from PIL import Image
img = Image.open("photo.jpg")
exif = img.getexif()  # dict-like access to EXIF tags
```
Note: no `exiftool` in this container. Use `identify` or Pillow for metadata tasks.

### Icons, Favicons, App Icons
**ImageMagick** generates multi-size ICO files directly.
```
convert icon.png -define icon:auto-resize=256,128,64,48,32,16 favicon.ico
```
For icon sets (iOS/Android), batch-resize with `convert` or `mogrify` to each required size.

### PDF & EPS (limited)
ImageMagick can read/write PDF and EPS but **Ghostscript is not installed** — complex PDF rasterization may fail. For PDF-to-image, prefer **Pillow** (for simple cases), **pdfplumber** (text/table extraction), or the **pdf skill** (for full PDF manipulation). IM's built-in PDF delegate handles basic operations.

### Seam Carving (Content-Aware Resize)
ImageMagick has **Liquid Rescale** (LQR) built in:
```
convert input.jpg -liquid-rescale 80x100%! output.jpg   # shrink width 20%, preserve content
```

### SVG Handling
ImageMagick rasterizes SVG via its built-in delegate. For SVG→PNG at specific sizes:
```
convert -density 300 input.svg -resize 800x output.png
```
No Inkscape or rsvg-convert available. For SVG manipulation, work with the XML directly or use Python's `lxml`.

## Complete Tool Inventory

| Tool | Type | Key Strength |
|---|---|---|
| **ImageMagick 6.9** | CLI suite | 260 formats, effects, compositing, batch ops |
| **ffmpeg** | CLI | Video/animation, frame extraction, optimized GIFs |
| **Graphviz** | CLI | Diagram→image rendering (dot, neato, etc.) |
| **LibreOffice** | CLI | Document→image conversion |
| **Pillow 12.1** | Python | General-purpose, EXIF, drawing, WebP/AVIF, freetype |
| **OpenCV 4.13** | Python | Computer vision, histograms, contours, morphology |
| **scikit-image 0.26** | Python | Scientific analysis, SSIM, segmentation, features |
| **Wand 0.6** | Python | Full ImageMagick API from Python |
| **imageio 2.37** | Python | Unified I/O, GIF frame sequences |
| **scipy.ndimage** | Python | Convolution, interpolation, labeling |
| **numpy** | Python | Raw pixel array math |
| **reportlab** | Python | PDF generation with embedded images |

## Key Constraints

- **No Ghostscript** — PDF/EPS rasterization is limited to IM's built-in delegate
- **No potrace/autotrace** — bitmap-to-vector tracing unavailable
- **No standalone optimizers** — no optipng, pngquant, jpegoptim, gifsicle (use IM quality settings or ffmpeg instead)
- **No exiftool** — use `identify` or Pillow for metadata
- **No Inkscape** — SVG manipulation is XML-level only
- **HEIC/AVIF read-only** in ImageMagick; Pillow supports AVIF read/write
- **ImageMagick is v6** — use `convert`/`identify` commands, not `magick` (v7 syntax)