I / O Nodes

The I/O nodes are the Chalice input and output nodes, which are used to import and create imagery and to render modified images to disk. Chalice networks generally begin with one or more Disk Input or Color nodes and end with a Disk Output node followed by an Exec node.

Unlike other nodes, the Disk Input and Color nodes do not have input connectors. They are source nodes which import or create imagery. The Disk Output node has a single input connector.

In addition to descriptions of the I/O nodes, this chapter also includes information about the image file formats that can be imported and exported by Chalice, and how to use proxy files in Chalice:

Image File Formats Supported by Chalice
Using Proxies in Chalice

The I/O nodes menu includes:

Color Node
Disk Input Node
Disk Output Node

Parameter Tabs in the Disk Input and Disk Output Node Panels

The Disk Input and Disk Output node panels include more tabs than can be displayed across the node panel at one time. To select a tab that is not currently visible, access the Tabs popup menu, which lists every parameter tab available for the node.

Click and hold down the mouse button over one of the Tabs icons (located on the left and right sides of the panel) to display the Tabs menu. Select a tab from the menu list and release the mouse button.

Image File Formats Supported by Chalice

The current version of Chalice imports and exports the file formats in the list below. However, you can add support for other image formats by writing a Chalice plug-in. (HTML documentation for plug-in developers is available from within Chalice by selecting "Writing Plug-ins..." from the Help menu.)

Image Format Notes

This section provides important information about certain image file formats which should be reviewed before importing and exporting these file types.

The Disk Input and Disk Output nodes feature specialized tabs for controlling aspects of the importation and exportation of certain image formats. In addition to DPX, Fido, FRP, and the IRIX-compatible movie formats described below, tabs are available for importing Maya, YUV (at NTSC, PAL, or HD resolution), and ZPIC as well as for setting compression options when writing Jpeg and Tiff files to disk.

Always review the default parameter settings in the format tabs for Maya, YUV, and ZPIC when importing these file types:

  • Only the RGBA or the Z channel data of a 5-channel Maya file can be imported into any one Disk Input node.
  • Unless the default is changed, YUV files will be converted to 8-bit data upon import.
  • A resolution must be specified for ZPIC files.

A formatting tab will only be activated when the associated format has been specified for import or rendering (otherwise the tab is grayed out). The parameters in these tabs are described in the Disk Input and Disk Output node descriptions later in this chapter.

Cineon (DPX / Fido) Formats

Chalice imports and exports Kodak Cineon 10-bit log imagery in DPX or Fido format. By default, the Disk Input node automatically remaps Cineon files to 16-bit linear colorspace, after which they can be treated like any other 16-bit imagery.

However, you also have the option to choose other conversion methods in the Fido and DPX formatting tabs in the Disk Input node. You can convert the log data to floating point linear, or you can choose to "insert" the log data into 16-bit or floating point linear to avoid clamping the highs. Such data is referred to as "Cineon Linear." You also have the option not to convert the log data at all.

Note:
The available import/export conversion options are described in the "DPX and Fido Parameter Tabs " section of the Disk Input node description. It is highly recommended that all users working with Cineon files review this information. Even if you are experienced with log-to-linear conversion issues, it will still be profitable to review how such conversions are handled in Chalice.
For a general overview of the subject, refer to Image Representation in Chalice in chapter 4, "Key Concepts ."

Viewing "Cineon Linear"

Although it is not the default option, Cineon Linear is a highly recommended conversion option for 10-bit log files to preserve the integrity of the image data. However, Cineon Linear will appear indistinct in node monitors using the default monitor display settings.

To view a Cineon Linear image, open the node Monitor and select one of the Cineon display LUTs or presets from the Presets/LUTs menu. Remember that these options alter monitor display parameters only, not the node data.

Cineon in the Frame Icon

If the image data in a node is native Cineon 10-bit log data or Cineon Linear (which is created by choosing one of the insert methods to convert the files to linear), the Frame Icon image will appear indistinct or black. The default Chalice setting for viewing node icons in the workspace is not optimized to display this type of data because the ideal display shift for Cineon Linear would make other types of linear data appear overexposed.

For more information, refer to chapter 8, "Monitors and Flipbooks ."

Adobe Photoshop Files

Chalice cannot read native Photoshop files created in versions newer than Photoshop 3.X, because Adobe instituted layering with version 4. However, you can flatten a Photoshop 4.X (or later) file, save it as a tiff, and import the tiff into Chalice.

Chalice Direct Image Format

Chalice enables you to import and export images directly in Chalice's internal file format. Although Chalice Direct Image (CDI) format is not likely to be the final output format for your shot, it does provide a very fast way to import and export frames of imagery that have been modified in Chalice.

Because CDI files do not employ compression, they can be quite large and require a great deal of disk space. Therefore, you may wish to avoid using this format for film resolution images.

Chalice FRP Files

FRP, which stands for "Fast Realtime Playback," is an internal format that Chalice uses to create single-file image sequences for realtime playback (hardware permitting). An FRP file can be created not only by specifying the format for rendering in a Disk Output node, but also directly from a flipbook, in which case the current flipbook sequence will be rendered to disk as an FRP.

To play an FRP, it is not loaded into a Disk Input node. Instead, it can be accessed from within Chalice at any time by using the "Play FRP Movie" command in the Chalice File menu, which will load the sequence into a Chalice flipbook for playback.

Movie Formats

The type of movie file format that can be imported and exported by Chalice depends, in part, on the system software your workstation is running:

  • Chalice users running NT can import and export AVI files.
  • Users on IRIX systems can import and export SGI, QuickTime, or MPEG.

Using Proxies in Chalice

All Chalice Disk Input nodes provide the option to create and/or specify proxy files, which are lower-resolution stand-ins for the final input frames. Proxies are often used when the full resolution inputs are very large files (2K or 4K film footage, for example). A proxy-resolution sequence can be much faster to view and modify as a shot is being built.

Another reason to use proxies is if the full resolution files are not available yet--for example, if all of the background frames haven't been digitized or if some of the finals of the CG elements haven't finished rendering.

"On-the-fly" proxy views have always been available in Chalice by bringing up a monitor image at a fraction of full size. In such cases, Chalice accesses the full resolution image and scales it for viewing in the monitor. However, it can be considerably faster to access lower-resolution files. Also, being able to scale to different resolutions in Chalice monitors does not address a situation in which the full resolution files are not currently available.

There are two main components to using the Chalice proxy system:

  • creating or specifying proxy files for an input or inputs
  • selecting a proxy level to work in globally

The actual proxy files are specified (or created) using the Disk Input node. The Chalice main interface also offers a global switch called "Proxy Input" that is used to specify the proxy level to work in for the grail file as a whole.

Note:
Unless you enable proxies (by checking the "activate" box in the Proxy tab), Chalice operates exactly as if there were no file-proxy capability. The full resolution source imagery is always accessed, and scaled as needed to fit the requested monitor size.

Other points to consider to get the most out of working with proxies include

  • how proxies affect monitor display,
  • matching default monitor resolutions to proxy file resolutions, and
  • keeping proxy files in sync with changes to full resolution inputs.

Activating File Proxies

  1. Always start by specifying the "Full Path" parameter of the Input tab.

  2. Full Path files are the full resolution image files that will be used to render the final shot.
  3. Then enable proxies in the Proxy tab and specify a medium and/or low resolution proxy.

  4. You can point to an existing file sequence to use, or you can press the Create Files button for that proxy level to create them.

    Proxy files must match the full resolution source files in bit depth and number of channels; otherwise an error is generated. This prevents modifications being made to proxy files that would be inappropriate if later applied to imagery of a different bit depth or number of channels.
  5. If the full path imagery is not available, change the Full Resolution parameter in the Proxy tab from "Use Source File" to "Specify Size" to specify what the full resolution and bit depth will be.

  6. Then proceed to point to the image files to be used for the proxies. (Obviously, if Full Path image files have not been specified in the Input tab, you will not be able to use the "create proxy" function for that imagery.)

Disabling a Proxy Input

You can disable proxies for a Disk Input at any time by deselecting the "Enable Proxy Files" box in the Proxy tab. When you disable proxies, the Full Resolution menu on the Proxy tab is automatically set to "Use Source File," because a full path sequence must be specified in the Input tab in that case.

Setting the Global Proxy Input Level

A global Proxy Input switch enables you to set the current proxy level to use: Full, Medium, or Low. This switch specifies which of the files in a Disk Input node will be accessed by the network, constrained by the variables discussed next.

Unless a proxy file has been specified for a source image in the Disk Input node, the full path image data is always used in the network. This is true whatever the global Proxy Input setting may be, making the switch irrelevant in this case. For example, if you bring up a Monitor Medium or Low, the source image is scaled down to match the requested size.

If proxy inputs are specified, Chalice will access them when it is more efficient--regardless of the Proxy Input level selected. For example, say that the global Proxy Input switch is set to Full and you open a node monitor at medium resolution. If the source Disk Input node has proxy files enabled, Chalice will use the file closest to the requested monitor size (scaling the image up or down a little if necessary to match the monitor size).

Note:
This means that you must keep all files specified in a Disk Input node in sync. Changes to full resolution inputs require that proxy files be updated or disabled.

If the global Proxy Input level is set to Low and you request a Monitor Full, Chalice will take the low resolution proxy input, if specified in the source Disk Input node, and scale it up, so that the resulting monitor image will look blocky. (To see the full resolution source image, the Proxy Input switch should be set back to Full.)

Defining Monitor Resolutions to Match Proxy Files

As described previously, Chalice will access the specified source file with the resolution closest to the requested monitor resolution and then scale it up or down if necessary to display it at the requested size. To avoid such scaling, you may want to redefine Monitor Medium and Monitor Low to match the proxy file resolutions for your current project.

Monitor Full is always 100 percent of the full resolution source image, but Medium and Low are both fractions of full resolution, and these fractions can be changed in the Proxy Preferences panel (which is accessed from the Chalice Preferences menu). By default, Medium is defined as half and Low as one-quarter of whatever full resolution is for the current node.

Say, for example, that you are working with 4K imagery and that your medium proxy files are 2K. However, your low resolution proxies are not 1K but typical NTSC resolution (720 x 486). Using the default Monitor Proxy values, a request for a Monitor Medium will display the 2K files (which are exactly half of full resolution), but a Monitor Low will access the video resolution files and scale them up to 1K (since Low is defined as a quarter of full resolution).

In this case, you can use the Proxy Preferences panel to redefine Monitor Low to be the same fraction of full resolution that a 720 x 486 image is of 4K imagery. (This fraction happens to be 0.175781. Chalice will do the calculation for you if you select a reference resolution in the preferences panel.)

Note:
This setting affects all node monitors opened at low resolution. Using the example of Monitor Low defined as the fraction 0.175781, bringing up a Monitor Low on a CG element that is 1K at full resolution will display an image that is 17.5781 percent of 1K resolution.

Other Tips for Working with Proxies

Proxy files are commonly used by specifying them in the Disk Input nodes, keeping the global Proxy Input switch at the default setting of High, and using Monitor Medium to access medium resolution proxies and Monitor Low to access low resolution proxies.

In this way you control access to the source images by selecting a monitor resolution. With the global Proxy Input switch set to Full, you can still work faster by opening a Monitor Medium for an input with a Medium proxy. When more precision is needed, you can access the full resolution file by choosing Monitor Full.

When working with proxies, it is also important to use fractions rather than pixels, where applicable, as the basis for spatial measurement values. For example, if you scale an image by specifying a percentage of full resolution in the Scale node parameters, this value will be equally valid for a proxy or a full resolution image.

Using Rescan Disk to Update Proxies

Proxy files must be kept in sync with any changes made to the full resolution source files. You can create new proxy files to replace the old ones by using the Create Files option in the Disk Input node. However, the updated proxy files you want to use may already have been created by someone else. In that case, use the Rescan Disk option for the proxy input to force Chalice to reread the disk and update accordingly. (Rescan Disk can also be used to update the full resolution input if necessary.) The rescanning process can take some time, depending on the sequence.

Chalice also provides a "Rescan All Disk Input Nodes" command in the Admin menu. This will rescan all Disk Inputs without having to go into each source node individually to press the "Rescan Disk" button. (Of course, the "Rescan All" command can take a long time to execute, depending on the contents of your grail file).




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