Shrinker
The Shrinker filter is a general filter.
The Shrinker filter shrinks the image. You set the maximum width and height, and the image is scaled to fit. The image's width/height ratio will always be preserved. This filter will never make an image larger.
In the default chain, there are two shrinkers. The first one is intended to help get a good overview, while the second one is meant to shrink the image to its final size.