I have found that sometimes I am looking for a particular visual blend effect, but I can‘t remember how they look or don’t know how they will work with my clips / images. Maybe you're new to Quartz Composer and would like to learn more about blends.

Anyway here is a little composition I knocked up to have a look at the different blend modes. Just connect an image or movie to each of the “Render In Image” nodes and use the up and down arrow keys to cycle through the different modes.