What are special effect filters? Before there was Photoshop, the average photographer had very little control over the look of their photos. One way to control what your pictures looked like was to use a filter. Manufacturers sold filters with names like star filters, normal fog filters, etc. A star filter would put points on lights to make them look like stars. A Rainbow filter added a rainbow to the photo. The fog filter made everything look soft and foggy.
With the advent of Photoshop, the need for filters is slowly fading as many of these effects can be created in post-production. There are still a few instances where it is easier to use a filter than to try to accomplish the effect in post-production, and there are also other times where a filter is the only way to create a particular special effect. For example – the star filter; although it is possible to change shiny lights into pointed stars in post production, it would be time consuming and difficult to change every single light. Using the star filter guarantees every light source will be a starburst.