Bit Expand Node

The Bit Expand node enables you to convert linear imagery from a lower resolution format to a higher resolution linear format (16-bit or float) or to log (raw 10-bit Cineon) format.

Note:
Cineon 10-bit log is considered a higher resolution format because of the fact that it can hold the same amount of image information per channel as 19 bits in linear space.

The Bit Reduce node is the complement to this node, performing the inverse of the Bit Expand operations. For the most detailed explanation of these conversion methods, refer to the Bit Reduce Node description.

Reversing a "Bit Reduce" Operation

Most frequently the Bit Expand node is used to convert imagery that was previously "reduced" (converted) in a Bit Reduce node. To use Bit Expand for this purpose you merely have to select the specific Bit Reduce node that was used, and Bit Expand will perform the inverse of that operation. No other parameters need be set when using this option.

Using Bit Expand

For converting imagery that has not gone through a Bit Reduce node (see above), you can choose from four different conversion methods: Black & Rolloff, Cineon Softclip, Linear, and Curves.

Converting to Cineon

The Black & Rolloff or Cineon Softclip method should be used when converting data to Cineon 10-bit log or Cineon Linear formats.

Converting to Linear

When converting to straight 16-bit linear or float linear, use the Linear method as it expands the input data to fill the colorspace specified for output. If necessary, you can use the Curves method instead of Linear. The Curves interface is more complex, but it enables you to manipulate splines on a graph to control the conversion curve for each channel.

Follow these steps:

  1. Specify the Input and Output formats in the Conversion tab.
  2. Bring up the Bit Expand work monitor.
  3. Select the type of conversion process you want to use from the Conversion Menu.

  4. Use the guidelines above to pick the method most suited to the converted data format.
  5. Adjust the default mapping parameters, if necessary, for the conversion method you have selected:
    • For Black & Rolloff, Cineon Softclip, or Linear conversions, use Light or Dark Intelligence to provide starting points for in/out mapping. You can then adjust these values manually as needed.
    • For Curves, manually adjust the conversion curves at each channel by dragging value points on the curve. You can add new points on the curves as necessary. Use the Slopes menu to adjust the shape of the curve into and out of the value points.
    • Note:
      Specific parameters for each method are described in the following sections.

Conversion Parameter Tab

"Reduce Node" Parameter

This parameter enables you to reverse the operations previously performed in a Bit Reduce node. You can either key the name of the appropriate Bit Reduce node directly into the entry field or select it from the associated popup menu, which lists every Bit Reduce node in the workspace.

Once you have specified the name, you will not need to enter any additional values or instructions. Chalice will automatically perform the inverse of each operation specified in the Bit Reduce node.

Work Monitor / At Resolution

First, select a display resolution for the work monitor from the At Resolution popup menu. Then click the plus icon to display the work monitor for this node, in which you adjust various conversion parameters. These parameters are described in the next section, "Bit Expand Work Monitor ."

Channel Mask

The Channel Mask parameter enables you to inhibit the modification of any channel by deselecting the Red, Green, Blue, Alpha, or Other channel buttons.

Input Is

The Bit Expand node accepts 8-bit through 16-bit linear or float data as input. You will not need to set this parameter if your input is 8-bit linear. However, it is necessary to specify the format type for 10-bit through 16-bit input.

Output To

The Output To menu enables you to specify the data format of values sent to output. You can convert the input image to Cineon 10-bit log, Linear 16-bit, or Linear float.

Frame Range Intelligence

Frame Range Intelligence allows you to draw the histogram information used by Light and Dark Intelligence from a range of frames rather than from a single frame. You can enter values directly from the keyboard or use the slider bar to set the range. The Light Intelligence and Dark Intelligence buttons work exactly like the ones located in the work monitor, which are described in the next section.

Bit Expand Work Monitor

The work monitor provides parameters to control the format conversion of the input and output types specified in the Node Panel.

Light and Dark Intelligence

The Light Intelligence and Dark Intelligence buttons are used in conjunction with the Black & Rolloff, Cineon Softclip, and Linear conversion methods. Click the button (Light or Dark) most descriptive of the input image, and Chalice will generate mapping values based on the input image data. You can then adjust these values manually as needed.

For more information, see the description of Light and Dark Intelligence in the Bit Reduce node description.

Parameter Menu

The Parameter menu allows you to select the conversion parameters to display for the method you selected from the Conversion menu.

Conversion Parameters

These two columns of tuners enable you to change the default mapping values used by the selected conversion method: Black & Rolloff, Cineon Softclip, or Linear.

Because these conversion methods use different algorithms, the values you enter will vary depending on the type of conversion you have selected. Specific instructions for each conversion method are outlined in the Conversion Menu section below.

Note:
The Curves method requires a different, graphical interface.

Cascade Buttons

If you would like the value you have entered in the red channel to affect all channels equally, select the cascade button. This will spare you from having to key numerical values into each parameter.

STED Buttons

A STED button is provided for both columns. You can click either button to display the Chalice Space-Time Editor (STED), which will enable you to animate these parameters over time. For more information, see chapter 9, "Space-Time Editor (STED) ."

Graph

The graph visually illustrates the conversion scheme specified by the controls. The horizontal axis represents the input image. The range will depend on the type of input selected in the Input Is menu on the Conversion tab in the node panel. The vertical axis represents the output values. These values will also vary depending on the type of conversion specified. Changes in the conversion parameters will be updated in the graph.

The Graph also displays a histogram for the color distribution of the input image at each channel. The horizontal axis represents the color values at a pixel. The vertical axis represents the number of pixels in the image with a particular color value. You can zoom in on sections of this histogram by sliding the triangular wedges located on the right of the graph.

Note:
Although the values on the horizontal axis are accurate for both curves, the vertical scale of the conversion curve and the histogram are very different. The values on the vertical axis represent output mappings, not the number of pixels for each color value. Therefore, the histogram display provides only general information about the shape of the color curve.

Display Depth Buttons

These buttons provide a graphical display of the conversion process in various formats. You can choose to display the data in Default view (i.e., the colorspace of the input image), Cineon view (0-4095), 14-bit (0-16383), 12-bit (0-4095), or 10-bit (0-1023). These values will appear on the horizontal axis. The vertical axis always displays the range of the format type sent to output.

Channel Display Buttons

These buttons turn on and off the graphical display for each color channel. All channels are turned on by default.

Color Picker

The Color Picker can display the RGBA value of any pixel or pixel area in an image. See the Bit Reduce Color Picker description for more information on how to use this tool.

Conversion Menu

This menu allows you to select the method Chalice will use to convert the input format to the output format. The default is Black & Rolloff. You can also use Cineon Softclip, Linear, or Curves. Each conversion method is described below.

Black & Rolloff

The Black & Rolloff conversion process enables you to optimize the conversion of an image file from a lower format, such as 8-bit linear, to a Cineon format, either Cineon Linear (16-bit or float) or raw Cineon (10-bit log). The default values are based on Cineon specifications.

The Black & Rolloff conversion method maps Low, Middle, and High color values from the input (left column of Conversion parameter tuners) to the output (right column).

The Low parameter specifies the lowest value included in the conversion. The Mid value represents the 90% density point. The High value sets the highest value in the conversion.

For a more information about this conversion process, see the Black & Rolloff Method section of the Bit Reduce node description.

Cineon Softclip

The Cineon Softclip setting enables you to convert imagery to a Cineon format using a conversion scheme based on Reference Black and White, Film Gamma and Display Gamma. The default values are based on specifications published by Cinesite and Kodak for this type of conversion.

The Reference Black specifies the lowest value included in the conversion. The Reference White value represents the 90% white value. The default is 4095, which maps to a 10-bit log value of 685.

Film Gamma refers to the gamma, or color distribution curve, of the input image. Display Gamma refers to the gamma of the monitor used to display the output image. The defaults are 0.6 and 1.0, respectively.

Note:
Refer to the equations in appendix C, "Softclip Conversion ," for the precise conversion process used in the Softclip operation, and to the Cineon Softclip Method section of the Bit Reduce node description.

Linear

The Linear method is appropriate for converting imagery to a higher linear format: 16-bit or float. It is not recommended for Cineon output. Linear allows you to specify the high and low values of the conversion only. You cannot specify a midrange value for this method.

In the Low parameters, you specify the mapping from low in the input to low in the output. In the High parameters, you specify the mapping from the input high to the output high.

Curves

Like the Linear method, the Curves method is used to convert imagery up to 16-bit or floating point linear, not for Cineon conversion. Curves allows you to manually adjust the format conversion curves in a graph. Unlike the other conversion options, you do not specify values for predefined parameters. Instead, you alter the curves for each individual channel by manipulating splines on a graph using points and slope functions.

See the section of the Bit Reduce node description entitled "Bit Reduce Curves Editor " for a detailed description of how to use the tools in the Curves Editor panel.

Advanced - Cineon Settings Parameter Tab

The parameters on this tab represent default values that are used by functions in Bit Expand that convert to or from Cineon data.

In most cases, these parameters should be left at their default values, which are based on specifications for Cineon conversion published by Cinesite and Kodak. Refer to appendix C, "Softclip Conversion ," for more information.




Table of Contents | Index



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