Then I read somewhere that we can actually create GIF images in command line mode using Imagemagick. But to do so you need to have Imagemagick installed on your system. To install it in Ubuntu, run:

sudo apt-get install imagemagick

This program has several features that would let you do all sorts of things with images. I was interested in converting a bunch of PNG files into an animated GIF file. To do so, we need to  rename the files in a way that they would lie in a sequence when arranged alphabetically (if you plan on doing it the easy way). Suppose you have files named slide_01.png, slide_02.png, slide_02.png….slide_xx.png, and you want to convert them to movie.gif, we run:

convert -delay 10 -loop 0 slide*.png movie.gif

The parameter delay inserts a desired delay between two consecutive slides. The number x used for delay inserts 10x milliseconds of delay between two frames. Loop parameter 0 makes it repeat infinitely.

If you had files with non-uniform names, then you need to input each of them in a sequence after the delay and loop parameters. Suppose you have file summer.jpg, fall, winter.jpg, fall.jpg and spring.jpg and you want to order them as fall, winter, spring and summer in the gif image seasons.gif with a 1 second delay between each of them, use:

convert -delay 100 -loop 0 fall.jpg winter.jpg spring.jpg summer.jpg seasons.gif

Here are some animations of numbers from 0 to 9 with varying delays.

The delay values specified the above cases were: 1, 5, 15, 25, 50 and 100.

GIF animation with 10 millisecond frame delay

GIF animation with 50 millisecond frame delay

GIF animation with 150 millisecond frame delay

GIF animation with 250 millisecond frame delay

GIF animation with 500 millisecond frame delay

GIF animation 1 second frame delay

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