ImageMagick

Information

Program info

See ImageMagick version:
```
  convert -version
```
Show available lists:
```
  convert -list list
```
Show available alpha compositions:
```
  convert -list compose
```
Show supported fonts:
```
  convert -list font
```
Show supported formats:
```
  convert -list format
```

File info

Get information about file:
```
  identify image.png
```

Convert

Rotate image by some degrees:

  convert input.png -rotate 10 output.png

Remove image profiles (EXIF, ICC, etc.) from an image:
```
  convert input.jpg -strip output.jpg
```
or (multiple images):
```
  mogrify -strip *.jpg
```

Pixel out an image:

  convert input.jpg -scale 25% -scale 400% output.jpg

Blur an image:

  convert input.jpg -blur 0x8 output.jpg

or (for large images):

  convert input.jpg -filter Gaussian -resize 25% -define filter:sigma=2.5 -resize 400% output.jpg

Convert image to grayscale:

  convert input.jpg -colorspace Gray output.jpg

Simulate a charcoal drawing:

  convert input.jpg -charcoal 1.2 output.jpg

Transform image to black and white:

  convert input.jpg -monochrome output.jpg

Replace each pixel with its complementary color:
```
  convert input.jpg -negate output.jpg
```

Resizing or scaling

Ignore aspect ratio:

  convert input.jpg -resize 64x64\! output.jpg

Only shrink larger images:

  convert input.jpg -resize 64x64\> output.jpg

Only enlarge smaller images:

  convert input.jpg -resize 64x64\< output.jpg

Fill area:

  convert input.jpg -resize 64x64^ -gravity center -extent 64x64 output.jpg

Percentage resize:

  convert input.jpg -resize 50% output.jpg

Resize using a pixel area count maximum:

  convert input.jpg -resize 4096@ output.jpg

Resize using a pixel area count minimum:

  convert input.jpg -resize 4096@\> output.jpg

Thumbnails and framing

Create a thumbnail in GIF format:

  convert input.jpg -format gif -thumbnail 100x100 thumb.gif

Create thumbnails in a subdirectory (./thumbs):

  mogrify -path thumbs -format gif -thumbnail 100x100 *.jpg

Resize the thumbnail to fit:

  convert input.jpg -thumbnail '100x100>' thumb.jpg

Cut the thumbnail to fit:

  convert input.jpg -thumbnail 100x100^ -gravity center -extent 100x100 thumb.jpg

Create multi-resolution favicon:

  convert input.png -alpha off -resize 256x256 \
    -define icon:auto-resize="256,128,96,64,48,32,16" favicon.ico

Photo handling

Average several photos:

  convert *.jpg -colorspace sRGB -evaluate-sequence median output.jpg

Create tilt-shift effect:

  convert input.jpg sigmoidal-contrast 15x30% \
    \( +clone -sparse-color Barycentric '0,0 black 0,%h gray80' -solarize 50% -level 50%,0 \) \
    -compose Blur -set option:compose:args 10 -composite output.jpg

or (faster):

  convert input.jpg -sigmoidal-contrast 15x30% \
    \( +clone -sparse-color Barycentric '0,0 black 0,%h gray80' -solarize 50% -level 50%,0 -write mpr:blur_map \) \
    -compose Blur -set option:compose:args 10x0 -composite mpr:blur_map \
    compose Blur -set option:compose:args 0x10 -composite output.jpg

Create a traditional film-like double exposure:

  convert input_1.jpg input_2.jpg -average output.jpg