This program is written in Java and allows a greenscreen effect on an image. It requires two images,
the first being the greenscreen image, which is some figure with a green background (gsImage), and the second being the replacement, or background image (repImage).
Once the images are input, it takes a tolerance (tolerance) from the user. The tolerance is measure of how strong the effect is, meaning the more strict the program is regarding its
replacement of green pixels in the greenscreen image. Using the tolerance, the green pixels in the greenscreen image are replaced with the pixels from the replacement image.
The two images are combined into a new file which is named after the greenscreen image appended with _merged, which is then compared with other files in the current directory.
If that same filename exists in the current directory, it simply adds a counter to the end of the filename. If that filename exists, then the counter is incremented until
a filename is found that doesn't already exist. This allows the user to play around with the tolerance to find a level that works best.