User Manual

Alternatively, an Auto command sets the RoI to fit whichever pixels are visible at the current
zoom/pan level in the viewer. This lets you quickly limit the RoI to whatever part of the
composition you’ve zoomed into.
To automatically draw the RoI:
 Choose Auto from the viewer menu next to the RoI button.
 Right-click anywhere within the viewer and choose Region > Auto Region.
When you no longer need to use the RoI, you can reset it.
To reset the RoI to the full width and height of the current image, do one of the following:
 Choose Reset from the viewer menu next to the RoI button.
 Right-click anywhere within the viewer and choose Region > Reset Region
from the contextual menu or from the toolbar button menu.
 Disable the ROI control, which will also reset it.
While the RoI Is Active
The RoI is only used for previewing your composition while you work, not for output from
Fusion. While the RoI is active, Fusion will only request rendering of the pixels inside the region
when it displays an image in that viewer. Flipbook Previews that you create in that viewer will
also respect the current RoI. MediaOut and Saver nodes will always use the full image
dimensions when writing the image to disk, ignoring any RoI you’ve set in the viewers.
The RoI improves not only rendering speed and memory use, but it can also reduce file I/O,
since Loaders and MediaIn nodes only load pixels from within the RoI, if one is specified. This
does require that the file format used supports direct pixel access. Cineon, DPX, and many
uncompressed file formats support this feature, as well as OpenEXR and TIFF in limited cases.
Please note that changes to the viewed image size or color depth will cause the pixels outside
the RoI to be reset to the image’s canvas color. This also happens when switching in and out of
Proxy mode, as well as during Proxy mode switching with Auto Proxy enabled. When the image
size is maintained, so are the last rendered pixel values outside the RoI. This can be useful for
comparing changes made within the RoI with a previous node state.
TIP: Right-clicking in a Viewer and choosing Options > Show Controls for showing
onscreen controls will override the RoI, forcing renders of pixels for the entire image.
Managing Viewer Lookup Tables (LUTs)
Lookup Tables, or LUTs, can be used to help match the appearance of a viewer to its eventual
output destination. They’re essentially image-processing operations that affect only the image
being previewed in the viewer, not the image data itself. There are two basic ways that LUTs
can calculate color transformations: The first is a simple 1D LUT, and the second is a more
sophisticated 3D LUT.
 The simplest form of a LUT is a 1D LUT. It accounts for one color channel at a time,
so it can make overall tonality changes but not very specific color changes.
 A 3D LUT looks at each possible color value (red, green, and blue) independently.
A 3D LUT allows for large global changes as well as very specific color changes to be
applied to images very quickly.
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