Color Node

The Color node enables you to create either a solid color field or a gradient color ramp using the values you specify. The output of the Color node can be manipulated just like any other image data. It occupies no space on the hard disk unless you save it as an image file.

The Color node enables you to

  • create horizontal ramps, vertical ramps, or solid colors
  • use either RGB or HSV color space to specify colors
  • specify the alpha channel value
  • specify the resolution, bit depth, and number of channels for the output

Tip:
It is often convenient to save specific Color node settings as a preset by using the "Save As" option in the Presets menu, which is located just above the Info tab on the Node Panel. For more information, refer to "Using Preset Parameter Values " in chapter 6.

Using the Color Node

Start by selecting a solid field of color or a gradient (a horizontal or vertical ramp). Then select the colorspace you want to work in: HSV or RGB.

Next, use the color parameters (the HSV or RGB color bars) to specify the output color. You can also adjust the alpha channel value in the Alpha tuner.

Finally, specify the Resolution, Channels, and Bit Depth per channel of the output.

Creating a Ramp

When you select a gradient, ramp slider bars appear at opposite edges of the color box. You can adjust the color (and alpha) parameters for each bar individually. Click on a ramp bar to select it (the bar will highlight).

Ramp Offsets

You can create ramp offset slider bars by clicking in the color box. Each time you click, Chalice creates a new offset bar. To delete an offset, select the bar and then click the red X icon. (This icon only appears when a ramp offset is selected.)

You can drag these bars vertically or horizontally within the color box to manipulate the color frequency distribution, or you can use the Offset parameter. When an offset bar is selected, the Ramp Offset parameter will become active to enable you enter a precise numerical value (in pixels) for the offset.

Color Parameter Tab

The Color tab provides parameter controls for the color channel values of the color or color ramp, as well as the output channels, resolution, and bit depth.

Color Ramp / Solid Color Buttons

The two Color Ramp buttons and the Solid Color button enable you to specify a horizontal color ramp, a vertical color ramp, or a solid color. For example, if you need to create a solid background color for later use in bluescreen or greenscreen compositing, select the solid color button.

Color Box

This displays how the color or color ramp will appear in the output. If the Alpha value is adjusted, this channel will also be displayed (as a grayscale strip) in the color box.

When a ramp has been selected, the color box can be used to create ramp offsets: just click within the color box to create an offset bar, which can be adjusted by dragging it with the mouse or by using the Offset parameter.

HSV / RGB Colorspace Selectors

If you select HSV colorspace, the Color parameter tab displays parameters for Hue, Saturation, and Value. The Hue parameter range is from 0 to 360, representing a color wheel. The Saturation and Value parameters are set in a range of 0-1.

If you select RGB colorspace, the Color parameter tab displays parameters for Red, Green, and Blue. The RGB parameters are set in a range of 0-1, which represents the percentage of the total contribution of each color to use. This makes these parameters consistent whichever bit depth you choose for output from the node.

Alpha

The Alpha parameter enables you to control the alpha channel value. The Alpha channel retains monochrome matte data and determines the extent of coverage of an element at a given pixel.

Ramp Offset

You add an offset to a ramp by clicking in the color box to create a ramp offset slider bar. The Ramp Offset parameter enables you to precisely adjust the position of the selected offset by keying in a numerical value or using the tuner to set the value, rather than by dragging the slider bars in the color box. The offset from the edge is expressed as an X (for horizontal ramp) or Y (for vertical ramp) pixel coordinate.

Dither Ramp

This checkbox becomes active when a horizontal or vertical ramp is selected and 8-bit channels have been specified for the output. In such cases, Chalice does the internal calculations in floating point math and then truncates to 8-bit, which can cause banding when a small color change is being stretched over a large area.

The Dither Ramp option adds random noise to the floating point value, before truncating, thus hiding the banding in noise. It is on by default, but if you should want to turn off dithering, simply uncheck the box.

Resolution

This parameter enables you to specify the width and height of the Color node output. You can key a pair of XY values into the data entry fields, or you can use the popup menu to access a list of many video, HD, film, and large format resolutions. When you select a resolution from the list, the corresponding XY values are entered into the Resolution parameter fields.

Channels

This parameter enables you to select which channels to output:

  • RGB
  • RGB Alpha
  • Alpha only

Bit Depth

You can specify the bit depth per channel of the output by selecting an option from the Bit Depth menu (the default is 8-bit):

  • 8-bit channels
  • 16-bit channels
  • floating point channels




Table of Contents | Index



Copyright 1996-1999 by Silicon Grail Corporation