Apple Shake 4 New Features - Manual (Page 29)

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Major Features and New Nodes
This chapter covers major new features, and new nodes
that have been added to Shake 4.
Support For the OpenEXR Format
OpenEXR (.exr) is an extremely flexible, cross-platform file format developed and
maintained by Industrial Light & Magic. Key features of the OpenEXR format include
support for the efficient storage of high dynamic-range image data using the 16-bit
float “half” format, and support for auxiliary image data channels. OpenEXR 16-bit float
and 32-bit float data channels can be read directly into Shake’s RGBAZ data channels.
In addition, OpenEXR 32-bit unsigned integer channel data can be read into Shake’s Z
data channel, although Shake’s image processing nodes cannot process this data.
Note: 32-bit unsigned integer channel data will only be useful to custom plug-ins with
built-in logic capable of processing the data within the Z channel.
A major feature of the OpenEXR format is its ability to support an extremely wide
dynamic range. Thanks to its floating-point support, a contrast range of up to 30 f-stops
can be supported with no loss of precision. Color resolution in 16-bit float (“half”) files is
1024 steps per f-stop.
Another advantage of the OpenEXR format is support for any number of additional
auxillary data channels, in addition to the standard RGBAZ channels. For example,
additional channels can be written to store luminance, surface normal direction
channels, velocity channels, and even individual lighting passes written from a 3D
rendering application.