Apple Shake 4 New Features - Manual (Page 30)

30 Chapter 2 Major Features and New Nodes
Shake Support for Auxiliary OpenEXR Data Channels
Internally, Shake only supports the processing of RGBAZ channels down the processing
tree. However, the FileIn node provides channel remapping options in the Image tab of
a FileIn node’s parameters. Each channel that Shake supports has a corresponding pop-
up menu. Each menu presents a list of every compatible channel within the referenced
OpenEXR file. Color channels that correspond to Shake’s supported channels are
mapped by default.
To remap any image channel:
1 Load a FileIn node that references an OpenEXR file into the Preferences tab.
2 Choose a new channel to map to from any color channel pop-up menu.
Channel remapping has the following restrictions:
• Any 16-bit or 32-bit float channel can be remapped within the RGBAZ channels.
• 32-bit integer channels can only be remapped to the Z channel.
Note: If you want to access multiple 32-bit integer channels within a script, duplicate
a number of FileIn nodes equal to the number of channels you want to access, then
remap each 32-bit integer channel to a Z channel of one of the duplicate FileIn nodes.
Support for Data Compression
The OpenEXR format supports several codecs, with options for either lossless or lossy
compression. Compression ratios range from 2:1 to 3:1.
Note: By default, FileOut nodes set to output OpenEXR images default to the Piz codec.
The following codec information appears courtesy of Industrial Light & Magic:
• none: No compression is applied.
• RLE: (Lossless) Differences between horizontally adjacent pixels are run-length
encoded. This method is fast, and works well for images with large flat areas. But for
photographic images, the compressed file size is usually between 60 and 75 percent
of the uncompressed size.
FileIn channel pop-up menus for two files with different image channels