ImageMagick is a suite of tools for Linux which allows you to manipulate images from the command line. The “convert” command allows you to perform image conversions and image transformations, and you can use the “identify” command to view the Exif data in your images. Another tool from the suite is “montage” which allows you to create a montage or proof sheet (or contact sheet) by combining a number of different images, with or without a border or frame.
To create a simple proof sheet, call “montage” with a list of the images to include plus one final filename for the output. For example:
montage img1.jpg img2.jpg img3.jpg mymontage.jpg
This will create a montage called “mymontage.jpg” composed of the files img1.jpg, img2.jpg and img3.jpg.
You can also use wildcards to include all the pictures in a directory or just those matching the wildcard (e.g. “holiday*.jpg”). Here is how to use all the JPEG images in the current directory:
montage *.jpg mymontage.jpg
By default, the “montage” command will try to fit each image into a 120 x 120 thumbnail and then arrange the images (tile them) in the most optimal way. You can override this default and specify a different size for the images. To produce 180×180 thumbnails with 4 pixels on the left and right of each image and 3 pixels below, use:
montage -geometry 180x180+4+3*.jpg mymontage.jpg
Note that because the +4 specifies how many pixels are on the left and right of each image, it means that the first thumbnail will be 4 pixels from the left of the contact sheet but the gap between the images will be 8 pixels, 4 on the right of the first image plus 4 on the left of the next image and so on.
To add a frame to each of the images, use the “-frame” option. This option also needs a parameter to define how large the frame should be. For instance, “-frame 5” asks for a frame 5 pixels wide:
montage -frame5*.jpg mymontage.jpg
You can also add a shadow using the “-shadow” option.
Montage can also produce thumbnails with a Polaroid effect. In essence, the thumbnail is framed with an off-white border and a curl is added to the image. To try the Polaroid transform, use:
montage +polaroid *.jpg mymontage.jpg
Note that the “+polaroid” option starts with a + sign.
This can then lead to some interesting effects. For example if the spacing between the photos is set to a minus number, the thumbnails can be made to overlap. Combined with the Polaroid effect, this can produce some novel output. Try the following:
Another useful option is “-rotate“. It allows you to specify a rotation for each of the thumbnails. For example, to rotate each picture by 30 degrees, try:
montage -rotate30*.jpg mymontage.jpg
It is also possible to set the background color of the montage. The color can be set using a color name (e.g. red, aqua, maroon, green, olive and so on) or using a RGB color number (e.g. #FFFF00 for yellow). The ImageMagick website has a full list of supported color names. To set the background to a pale turquoise, use: