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In this video, we'll take a look at Nuke's color management.
In this first section, let's take a quick overview of the color management
features and there are three main features. One, Nuke works in 32 bit float,
two, Nuke works with High Dynamic Range, images, and three, everything is
done in linear light space. All of the pictures that you see in these
videos are included in the project media folder, which you can download so you
can play along too. Let's take a look at the 32 bit float.
I have this 8 bit TIFF image here in the Viewer. As I rub the cursor over the Viewer, you can
see the floating point precision RGB values down here at the bottom
and you could see the amazing precision of the Viewers.
But I want to demonstrate how the 32 bit floating point protects all of the
images from any damage in image processing, in order to maintain the highest
possible quality feature film effects. I'm going to select the Marcie Input node,
come up to the Color tab and add a Multiply node.
I'm going to scale the Marcie RGB values down by 1/1000th, .001 and of course,
the Viewer goes nearly black. I still got some pixels in there. You can
see down here at the bottom of the Viewer that I've still got some code values,
but they're mighty tiny. I'm even going to add a Blur node in order
to break up any possible concatenation of operations.
Selecting the Blur node, I'll add another Multiply node and this time I'm going
to scale Marcie up by 1000 and she's back. In fact, I can connect the original Marcie
here to the second input of the Viewer and as I bounce between the two inputs,
you can see there's absolutely no degradation to the picture, even though it
was scaled down by a factor of 1000 and then scaled back up.
Next, we'll take a look at High Dynamic Range images.
Here's an EXR file. As many of you know, these are very High Dynamic Range images.
In fact, you can see there are code values in here that are over 100.
Now they look clipped in the Viewer, but that's because the Viewer can only
display code values between zero and 1.0. Nuke goes far beyond 1.0.
I'm going to scale down the Viewer again. In fact, I'm going to take it down even smaller.
I'm going to inch it way down like that and you can see there's still color
information in that picture. Look at those code values. 50, 126 and 100.
I'll put the Viewer back and re-home it so we can take a look at this
10 bit log Cineon image. Cineon images are also High Dynamic Range
images. Instead of being floating point, they're 10
bit integer log images, but when they come into Nuke and are converted to linear
light space, they expand up to their full dynamic range with no loss of quality.
Now again, the fire looks clipped in the Viewer, but you can see in here there
are code values way over one. In fact, we can zoom in here and again I'm
going to turn the Viewer again down and now we can see the very high
code values in the 10 bit Cineon log image. I'll re-home the Viewer and reset the Viewer
again back to normal. So, what is this linear light space?
Linear light space means that the code values of the pixels represent actual
scene illumination, not brightness relative to the eye.
Nuke uses linear light space for three very important reasons. One, proper
image processing math. When you are scaling or multiplying RGB values or
multiplying two images together, if they're not in linear light space, the math comes
out wrong. Two, compatibility with chi. Cgi is rendered
in linear light space, but when it's written to disk, it gets converted to other
color spaces. Since Nuke has 3D rendering capabilities,
it must be able to render cgi the same way that RenderMan or Maya does and that's
in linear light space. The third reason is for mixing image types.
You'll notice that I had an 8 bit linear TIFF, an EXR High Dynamic Range image,
and a 10 bit log Cineon file. These three images are in completely different
color spaces, but when they're brought into Nuke, they're all converted to
linear light space, so they're all totally compatible with each other and could
be mixed perfectly. In our next movie, we'll see why it's essential
that almost every image we bring into Nuke has to be converted to linear light
space and we'll also take a look at Nuke's color management workflow.