The PXL tool has a single image output. It has a single, fixed primary input (which can be unconnected, when used as an image generator). Further image inputs can be added to the tool, which allows for an arbitrary number of secondary image inputs to the tool. These secondary inputs can also be removed from the tool. Because it supports masking, the PXL tool also has a standard masking image input.

The PXL tool allows the user to create an arbitrary number of animated scalar float inputs, to be used as parameters to the PXL script. Because of UI space restrictions, only the first ten scalar parameters will be shown in the UI; however, all parameters can be seen in the composition browser. These parameters are passed as arguments to the main() function of the PXL script.