The ultimate visual goal of an electronic image is to combine pictures from various sources and edit them in a fashion that they appear to have already been shot at precisely the same time, under exactly the same lighting conditions, with the exact same camera. To do this all perfectly, it is vital to have a good understanding of the technology, because many of the obstacles you will run into are, in fact, not really artistic barriers. They come from underlying technical issues which aren’t in any way evident to the casual onlooker but create inconsistencies in the shot.
The programmers of digital compositing software have tried to create programs so that the technology can be used by artists to hide the compositing artifacts and obvious inconsistencies, and to a large degree they’ve triumphed. On the other hand, no amount of artistic training will help you to correct movement track jitter caused by camera shake or an image that is grainy.
It requires three different bodies of knowledge to be a fantastic digital effects artist: technique, the tools and a great eye. The knowledge of your applications is only knowing the best way to use your specific compositing software package. You become a seasoned veteran, to the point where you’re seeing most difficulties for the third or second time and you know exactly what to do about them. The beginner, however, is always confronting issues and it takes time to run through all the solutions that are poor to arrive at the great ones.