ImageMagick is a collection of tools to mozify images, mostly from the CommandLine. Capabilities include:
- Resize, rotate, sharpen, color reduce, or add special effects to an image
- Create a montage of image thumbnails
- Create a transparent image suitable for use on the Web
- Turn a group of images into a GIF animation sequence
- Create a composite image by combining several separate images
- Draw shapes or text on an image
- Decorate an image with a border or frame
convert -sample width x height input.jpg output.jpg
The widths/heights can also take % values. It scales proportionally, so going 25%x25% on a non-square image will still make it come out non-square
Joining images together
convert files +append output.jpg
The +append appears to join them together left to right. -append possibly does something else. Haven't really looked into it.
Situation: You have a bunch of digital photos that you want to string next to each other for a website banner
1. Resize them all to 400px high (Just for ease of doing stuff later)
for img in *.jpg
convert -sample x400 "$img" "$img"
2. Join them together
convert *.jpg +append output.jpg
This will of course join them in alphabetical order. You may want to do something about that.
3. Final resize/add gradients in TheGIMP