The BCC+ Linear Luma Key Filter is a 32 bit hardware accelerated filter that creates a key from a single channel in the source. This type of filter is called a luma key, because the key is usually created from the image luminance, but you can also use any single RGB channel. You might want to examine the individual channels of the source and use a channel that provides more contrast between the foreground and background than the luma channel.
Presets and the FX Editor
The FX Editor provides a convenient way to store and retrieve factory installed and/or user generated filter presets. To select a preset, open the FX Editor interface and pick one from the Presets panel. Click the apply button in the FX Editor to return to the host user interface.
To save a custom preset, click the “Create Custom Preset” icon in the top right corner of the parameter list, next to the filter name, set a name for the new custom preset in the dialog that appears and click done.
Filter Parameters
Mocha Mask and Track provides a way for the user to select and track which pixels in the filtered source are actually going to be affected by the filter, via the generation of image based mattes, gradient mattes and vector shape masks. Mocha planar tracking and vector shape masking options are included in the PixelChooser, which allows for the generation of motion-tracked mask shapes as a hold-back mask.
For more information on the Mocha Masking and Tracking, Click Here.
Compare Mode
The BCC Compare Mode provides a convenient mechanism to compare the effect result with the original source layer. It provides several variations on basic split-screen views with the filtered clip placed next to the unedited original.
For more information on the Compare Mode, Click Here.
Make Key From: Determines which channel is used to create the key. Options include:
- Luma
- Red
- Green
- Blue
Output: Determines how the output of the filter is rendered.
- Composite: the filter uses the new alpha channel, making portions of the image partially or completely transparent when composited over the new background.
- Composite-Inv Alpha: inverts the new alpha channel.
- Show Matte: Displays the matte instead of the composite, allowing you to view the matte as you make adjustments.
- Show Invert Matte: Displays the inverted matte.
- Gel: allows you to create artistic gel effects using an alpha channel generated from the image. A Gel effect applies a transparent solid color, similar to a theatrical gel, to the source image. The alpha channel created by the filter is used to composite the chosen Gel Color over the background.
- Gel-invert-alpha: inverts the new alpha channel and uses it to composite the Gel Color over the background.
- Mask Transparent Pixels: allows you to view the source image with a 50% red mask over the pixels that will be transparent.
Gel Color: Used to select the color of the gel used in the effect. Select from eith the color chip or use the color picker to manually select pixel color.
Key Type: Used to determine how the key uses the threshold value and the image’s color or luminance information.
- Key Out Brighter: keys out pixels whose value is higher than the Threshold value.
- Key Out Darker: keys out pixels whose value is lower than the Threshold value.
- Key Out Similar: keys out pixels whose value is close to the Threshold value, within the range set by Key Similarity.
- Key Out Dissimilar: keys out pixels whose value is not close to the Threshold value, outside of the range set by Key Similarity.
Threshold: Used to control the sensitivity of the key to changes in color or luminance. When Key Type is Brighter or Darker, pixels brighter or darker than the Threshold value are keyed out (made transparent), and the Key Similarity setting is ignored. When Key Type is Similar or Dissimilar, pixels whose brightness is close to the value of Threshold Level, and within (Similar) or outside of (Dissimilar) the range set by Key Similarity are keyed out. You can create soft wipes by animating Threshold.
Similarity: Used to set a range of luminance values for which pixels are keyed out or kept in, depending on whether Similar or Dissimilar is chosen as the Key Type. The Similarity value and the Key Type can create mattes that change from opaque to transparent as the luminance changes from black to white.
Softness: Used to soften the matte by increasing transparency in pixels that are close to the borders of the key color region. You can use Softness to soften the matte edges so the colors of the image change gradually from point to point, or to create artistic blended mattes in which the image gradually becomes transparent as you move into the Key Region.
Post Blur: Used to blur the alpha channel after the matte is created. Use Post Blur to soften the edges in the matte for sources with high-contrast edges.
Gamma: Used to control the value of the middle tones while leaving the white and black of the image unaltered. The gamma parameter controls a gamma adjustment that is made to the derived alpha. increasing gamma spreads the alpha so that the matte is more opaque.
Alpha Offset: Used to control an offset that is added to the output alpha. You can create a transition by animating this from –255 to 255. At a value of -255, the entire image keys out. At a value of 255, the entire image is opaque.
Choke: Used to apply a choke to the matte. Positive Choke values tighten the matte around the foreground image, while negative values pull the matte away from the edges of the foreground image.
The Region Group
Region of Interest: The Region of Interest setting determines the shape of the region in which the filter is applied. You can apply the filter to an area Inside Rectangle, Outside Rectangular, Inside Oval, Outside Oval, or choose All to filter all pixels in the image, regardless of their location.
- inside rectangle
- outside rectangle
- inside oval
- outside oval
- all
Top-Left x/y: Sets the top-left position of the region along the x/y axis.
Bot-Right xy: Sets the bottom-right position of the region along the x/y axis.
Outside Region: Used to control the processing of points outside the region. e
- Make Alpha: Clears the alpha channel for these points. Use Make Alpha if you have chosen a region that includes all of the desired foreground (opaque) pixels.
- Use Existing Alpha: leaves these points unprocessed, and uses only the alpha information in the original image.
GPU Rendering: This popup allows toggles renderer in use for the filter.
- Default: By default the filter will utilize the installed video card and bases the render on the project settings.
- 16 Bit Float: Sets the render to 16 bit float
- 32 Bit Float: Sets the render to 32 bit float
- Disabled: Disables GPU rendering and switches to software rendering.