There are many different types of special effect filters.
Color graduation filters can add colors to the image adding a touch of reality, such as adding a darker shade of blue to the sky. They come in different tones, usually from 1 to 5 with 1 having the least amount of change and 5 being the densest amount of color. There are also solid color filters which, like graduation filters, add a tone of color. The difference is that it color casts the entire photo rather than just a portion. They also come in ranges from 1-5 with 1 being the weakest change and 5 being the strongest amount of color.
Star effect filters, depending on the pattern and the size of the grid, give light sources and reflections a multi-beam star look. Most of these filters have a mount so the photographer can turn the filter to get the desired effect of the star. The star filters come in choices of a four point star, a six point star, and an eight point star. There are also spectral cross filters which will not only give a cross effect to the image, but softens the focus as well.
Soft image filters and fog filters can be used when you want a look of surrealism in your photos. Soft focus will rid the image of sharpness and give a blurred look, while a fog filter gives the image a look as though it’s been taken in a fine bright mist, such as when it’s sprinkling outside or when it’s still very early in the morning.
Multi-image filters are another way to play with your photography. When you attach a multi-image filter to the front of your camera, you can almost get the effect of what an insect sees through its eyes. You can get them in ranges such as three images horizontally, five images in a circle with the fifth image being in the center, or even get them with the multiple images being different colors.