Lacq’ing in Depth

The Levels node in Conduit is basically equivalent to the Levels adjustment in Photoshop, so it’s easy to think of it as an image operation foremost. Yet Levels actually performs a very general-purpose math operation that can come in handy in many situations.

Consider an effect that takes a value from the user using the Slider node. The slider’s value is usually in the range 0 to 1 (what is often called the “standard range” in Conduit because it’s the range for visible pixel values). What if we want this slider to drive a value that needs a larger range — for example, a 2D Transform node? If we want to use this slider to move the image up to 100 pixels in either direction, we’ll need to change the slider’s input value’s range from [0, 1] to [-100, 100].

This could of course be accomplished by using a few basic math nodes:

But that looks rather unweildy for such a simple operation… So let’s use Levels instead:

See what happens in Levels? Input black and input white specify the original range (in this case, 0 to 1). Output black and output white specify the output range. This performs exactly the same math as the Multiply+Subtract nodes in the first screenshot.

Don’t forget that the Clip to 0-1 setting is enabled by default when a Levels node is created, so you need to uncheck that box. (If you don’t, Levels will clip all negative values to zero and all >1 values to one.)

…Hello. Anybody there? The stage lights are so bright, I can’t see you. Ahem. Thanks for showing up.

My name is Pauli Ojala, and I’m the guy in charge of a small company called Lacquer specialising in visual effects software. Our first product is Conduit, a plug-in that provides a node-based compositing environment directly inside Apple’s Final Cut Pro editing software. In addition to being convenient and affordable, Conduit is also fully GPU accelerated so it’s pretty much the fastest compositor you can find. (Don’t take my word for it — download the trial from our publishing partner dvGarage’s site and see for yourself.)

In this blog, I’d like to present some cool Conduit features and tricks. Some of the upcoming tips may already be familiar to you if you’re a member of Pixel Corps, as they have been posted in the Conduit forum there.

I’m going to provide .conduit files whenever possible, so you can try these ideas in your own projects without having to rebuild them from scratch. After all, easy reuse of effects (”build once, use forever”) is one of the major reasons why node-based compositing is so cool… But I hope to be able to show you a couple of other reasons too.