Lacq’ing in Depth

So, the big update on which we’ve been working for quite a while has been released. It’s called Conduit Suite, and it significantly expands Conduit’s reach: in addition to the existing plugin which works in Final Cut Pro and Motion, the Suite includes plugins for After Effects and Photoshop, as well as a brand new standalone application, Conduit Live. (To see Conduit Live in action, check out this video tutorial by dvGarage.)

The After Effects and Photoshop plugins are also available for Windows. These are not crippled ports: they offer the same Conduit Editor user interface. Conduit’s rendering backbone, the Conduit Pixel Engine, has been ported to Windows’s native graphics interface Direct3D, so you’re getting the best GPU rendering performance available on the platform just as with Conduit on the Mac.

The Conduit Suite gives you access to Conduit in 7 different applications: FCP, Motion, AE/Mac, PS/Mac, AE/Win, PS/Win, Conduit Live. Of course the same effect setups (.conduit files) work in all these applications, so it doesn’t matter where you build an effect, you can deploy it practically anywhere.

Interested yet? Our partner dvGarage is running a pretty hot sale: the entire Suite is only 149 USD until February 20, 2008. (For only $50 more, you can also get dvMatte Pro 3 for true keying nirvana!)

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Anyway, enough with marketing and on to the real content: to celebrate the occasion, I’d like to show something simple with Conduit inside Photoshop. Let’s start with this snapshot I took some years ago:

We’d like to place the lion in another background, so in practice we’ll just key out the sky:

I’m using the 3D Keyer because it’s easy and quick for keying out an arbitrary color. Levels is used to tweak the matte’s black/white points, and Exposure is used to tweak the layer’s color — nothing special going on there.

So what happens at the end of the conduit? Set Matte is used to apply the key matte to the image, and then it’s fed to the output. This means we’re giving back to Photoshop an image with an alpha channel. The actual compositing of the keyed lion over the background happens in Photoshop. Here’s what it looks like in Photoshop’s layers panel:

IMO this technique makes a lot of sense because it combines the strengths of Conduit and Photoshop.

Another thing: notice the label “Smart Filters” in the screenshot above? In Photoshop CS3, Conduit works as a non-destructive smart filter: you can go back and edit the effect in the Conduit Editor simply by double-clicking on the Conduit label in the layer’s properties. It’s like Adjustment Layers in Photoshops of the past… Except that Conduit has a hundredfold more capabilities than Photoshop’s simple built-in adjustments. (Thank you Adobe, I love smart filters!)

So here’s what the composite looks like, with the roughly keyed lion over a very plain gradient background:

Hmm. I think the lion and those white clouds might look nice with some glow, and maybe I could experiment with the color a bit. Well, those smart filters definitely come in useful; I’ll just open the Conduit Editor and add some nodes…

(Figuring out what’s happening here is left as an exercise to the reader.) Here’s the final image with a text layer added:

To recap, this Photoshop composite contains three layers: the background gradient, the text, and the lion. The only filter used is Conduit, which was applied to the lion layer. The node tree shown above does all the hard work: keying (sky removal), glow, color adjustments.

Are you seeing the benefits yet? We could have accomplished something similar with a combination of adjustments, filters and selection tools in Photoshop… But by building it in Conduit, everything happens within a single interface.

This way, the effect is also eminently reusable. Just save it as a .conduit file and it can be applied to another layer in another Photoshop document… Or a layer in an After Effects composition… Or a video clip in Final Cut Pro… Or even a live HD video stream in Conduit Live.

This is something of a FAQ: how does one apply a mask (a.k.a. matte) to an effect in Conduit, so that the effect is applied only to certain parts of the image?

There are a few ways to accomplish this. If the effect to be masked is a single node and it has an Effect opacity parameter, you can simply plug the mask image into this parameter input:

But if the effect is more complex, maybe consisting of multiple nodes, you’ll need to use a node to combine the original image with the effect. You could use the Blend node for this purpose:

The Blend node’s Bias parameter controls the blending of the two input images. This parameter only accepts a scalar (=greyscale) image as input (as indicated by the light-blue color), so I’ve added a Separate RGBA node to separate the alpha channel from the mask image.

Alternatively, you can achieve the exact same result by using an Over node:

The light-blue middle input on the Over node is the mask that controls where the top image is composited over the bottom image. In this case, the top image is the one with the Bezier Curve applied.

Whether to use Blend or Over is entirely up to personal preference. (I prefer Blend because it somehow makes more sense to me to think of this operation as blending two images, rather than compositing one on top of another. But like I said, the end result is exactly the same either way.)

We’re getting ready to release a new version of Conduit. In addition to supporting more host platforms, this 1.6 update makes some new features available to current users of Conduit for Final Cut Studio. There’s no upgrade cost, it will be a free download.

One of these new features is the Embedded Image node. It allows you to load an image directly into the conduit — no more need to put still images in the plugin’s image wells!

Once an image is loaded into an Embedded Image node, it stays as part of the .conduit file (there’s no dependency on the original file). This is highly convenient for images that are part of the effect, such as a mask used to create a specific look. This post shows one example.

As you may already know, most nodes’ parameters in Conduit can be driven by an image. This allows a wide range of interesting per-pixel effects that are essentially impossible in traditional graphics applications. For example, in After Effects you can apply a gamma to the entire image… But what if you wanted a different gamma value applied to each pixel?

While impossible in AE, it’s a breeze in Conduit. To demonstrate, I’ll reuse this image which previously made an appearance in this post:

Here’s the mask — just a plain ellipse drawn in Photoshop, rotated and blurred:

To control each pixel’s gamma value with this image, we just need to plug the image into the Gamma node’s gamma parameter. I’d like to perform this operation in linear light colorspace, so I also need two colorspace conversion nodes. Here’s the effect:

(Notice the blue node? That’s Embedded Image.) Ok, clearly the mask image is much too contrasted, we don’t want the image to go all black in the corners. Some tone adjustment nodes should take care of that…

The mask image’s black level was raised and its steep falloff flattened. These are the settings for the Bezier Curve and Levels nodes.

What next? Maybe we could add a color tint using the same mask. For basic tinting, the Multiply node works just fine. But the mask we have is black & white — to get a duotone color image from it, we can use the Gradient node to map the black/white into colors (this technique was discussed in more detail here). The colors chosen here are light orange tones:

The result image:

Out of curiosity, what would this effect look like if we didn’t use the linear colorspace? That’s easy to find out by simply bypassing the Video->Linear and Linear->Video nodes…

This look is more artificlal, with steeper contrast and greater saturation variation in the shadows. But since Conduit is non-destructive, you can always keep experimenting to find a happy medium between these looks: things to try might be tweaking the colors plugged into the Gradient node, or entering different values for the “gamma” parameter in the Video->Linear->Video conversion nodes.

The familiar Gaussian blur filter eliminates sharp detail, leaving only large shapes of color. If we think of the image pixels as a waveform, the blurred image contains only the low frequencies of the original image – the Gaussian blur is therefore a low-pass filter. Sometimes we might want the opposite: an image filter that eliminates large scale color variation and leaves only sharp details. This kind of high-pass filter would therefore be the functional inverse of a Gaussian blur.

We can in fact build a high-pass filter simply by subtracting a blurred image from the original:

Let’s try using the high-pass filter for smoothing skin. Here’s a DV image of some wrinkles… (Yeah, I didn’t need to go very far to get this image.)

The result of the above high-pass filter looks like this:

And with a couple more nodes….

….my hand looks 20 years younger. (Of course what really matters is the way it makes me feel. More self-confidence thanks to the new, improved formula!) Roll over to compare with original image.

Quick overview of how the effect is constructed: the high-pass matte is slightly expanded and blurred, then used as a mask to composite a blur over the original image. (The blurred image is marked as “wrinkle fill image” in the node screenshot above.) The result is then masked using a Color Range Key into the shadows and midtones of the hand. This is because I didn’t want the blur to smoothen out those illuminated hairs on the hand – the result would have looked too artificial.

What is this effect good for? I would imagine that certain segments of the video production industry have an interest in making skin look airbrushed… But I wouldn’t know anything about that.

Of course you don’t have to settle for smoothing out details. The “wrinkle fill” image could just as well be a sharpened version of the original, in case you want to make those wrinkles really pop out – for example if you’ve shot a documentary in Afghanistan, but the 97-year old refugee doesn’t look quite old enough.
(Disclaimer: you may lose your Oscar if the trick is exposed. Please don’t take documentary production advice from me.)

I’ve finally installed Final Cut Pro 5.1.4 (I was hesitant to upgrade a working 5.1.2 installation), and it seems to work fine. Thanks to the fine developers at Apple for taking rapid action to fix the issues in 5.1.3!

In this post I’ll show a simple way of smoothing out the wrinkles in a matte’s edge. Images speak louder etc., so here’s “before” and “after”:

The initial jaggy matte image was actually created using the following simple keyer:

For the smoothed effect, all we need to add is another Levels node and a Gaussian Blur:

The important trick here is that the second Levels node has been set to not clip values into 0-1 range (which you can tell by the color — the Levels node above is red, which always indicates clipping in Conduit). The parameter settings on the Levels node look like this:

These numbers 0.547 and 0.601 were simply “eyeballed” by dragging the sliders, they have no special significance… What happens with these settings is that the Levels node stretches tone range 0.547-0.601 into the range 0-1. And because clipping is off, it also stretches values outside that range in the same proportion: anything below 0.547 in the original image will go below zero, and anything above 0.601 will go above one. Thus the result image contains values that are mostly far outside the 0-1 range.

Applying the Gaussian Blur to such an unclipped image naturally results in an image that has a similarly “strange” value range. But we can’t really see those values — upon display, any pixel values below zero is clipped to black, and anything above one is clipped to white. So although there’s a HDR blur contained in the black and white areas, all we see is a sharp outline:

Does this make sense to you? Dealing with floating point images may require shifting some mental gears about what digital color and pixels really are… But in the long run, you can benefit from adding these little HDR tricks into your effect arsenal. The edge smoothing effect is pretty strong in the above image for demonstration purposes, but when applied frugally, it might be just what you need for tidying up a key on some occasion — or perhaps you can think of some artistic use for it.