Special effects have become the key selling point for most of the block busters produced by big film companies the world over. Audiences' expectations have skyrocketed and it is a constant challenge for film makers to come up with more dazzling effects that movie audiences have never seen before.
There is a wide array of special effect software that enables technicians to take outlandish scripts and turn them into believable imagery. What is more astonishing is that all these software are legally available for free as trial versions from the respective company sites. You can also download them from the link shown below in the last paragraph. There are probably as many kinds of effects software as there are effects techniques. What was done manually a couple of years or decades ago are now being done using software.
Animation for instance was done earlier by photographing hand-drawn or hand-painted images on sheets of celluloid and running the images in sequence through a movie projector. Senior animators created the poses for the characters at key frames in the animation and junior animators drew the in-between frames known as 'tweens'. The same principle is now used in computer animation where the computer artist draws the key frame while the computer does the 'tweening' between two consecutive key frames.
Compositing is another major technique used profusely in special effects. Creating mattes to mask certain portions of the frame and to make other areas transparent is a painstaking job if done manually. Each layer of the composite needs a separate matte, and if the shot requires around five layers for instance, every single frame in that movie clip would then need five mattes. Since the movie reel runs at 24 frames per second, even a short 10 second clip would need 240 frames which in turn require 1200 mattes to be created for all the 5 layers in the composite. Movies like Star Wars which have layers upon layers of composites are extremely difficult to make, precisely for this reason.
Fortunately special effect software packages have come to the rescue here too. There are a number of high-end as well as entry level software that make compositing layers of shots one over the other, extremely easy. Software packages are also available for other techniques such as match-moving, video editing, sound editing and camera motion control. Special effects software have not in any way reduced the need for creativity however; they have just taken on the task of doing the mundane work, freeing the computer artist to take over the creative side of things.