nip2, the "free love child of Photoshop and Excel," is the GUI of vips. You don't directly edit images --- instead, like a spreadsheet, you build relationships between objects. nip2 actively manages these relationships: if you change an object property, the change is propagated "spreadsheet-style."
Like vips, nip2 is fast and needs little memory. You can comfortably work with multi-gigabyte images on very modest hardware.
In addition to the visual programming interface accessible through the GUI, nip2 has command-line and batch modes. It even has its own functional programming language (for writing extensions). [Less]