Compositing Hi-Res Stereo Images - Nuke 101: Professional Compositing and Visual Effects - page 340

of color management to compensate for other external problems that make them
nonlinear.
Reviewtwomainnonlinearcolorspaces,sRGBandlog,andunderstandwhythey
exist.
• sRGB shows the reverse of what the nonlinear monitor you're using is
displaying (yes, that means all your monitors, even that really good new
Apple LED cinema monitor, even that one). sRGB is applied to show you
the real image on the nonlinear monitor. You can click the sRGB curve
in the Curves List window on the left to see the color correction that will
be applied to an sRGB image. This curve will be used just like in a Col-
orLookup node.
• Log (sometimes called Cineon) is there to compress and better mimic that
large abundance of colors found on a celluloid negative. It's used when
scanningfilmtodigitalfiles.YoucanclicktheCineoncurveintheCurves
List window on the left to see the color correction that will be applied to a
log image.
When you bring an image into Nuke, Nuke needs to convert it to linear so that all
images that come in are in the same color space, and so that mathematical oper-
ations give you the results you are looking for (a blur on a log image gives very
different results than a blur on a linear image). To convert all images to linear,
Nuke uses lookup tables (abbreviated LUTs). LUTs are lists of color-correcting
operations similar to curves in the ColorLookup node. Nuke uses these LUTs to
correct an image and make it linear and then convert it back to whatever color
space it came from or needs to be for display or render.
The LUT tab is split into two areas, the top and the bottom. The top area is where
you create and edit lookup tables. The bottom part sets default LUTs for different
image types.
2. ClickCineonatthetopleftlistofavailableLUTstoseetheLogColorspacegraph
( FIGURE 8.3 ) .
Figure 8.3. Select a graph in the list at left to display it at right.