BCC+ Linear Luma Key

Category: BCC Key and Blend

Effect Name: BCC Linear Luma Key

The BCC+ Linear Luma Key, part of the BCC Key and Blend category, 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.

Working with the Filter

FX Editor and Presets

• Use the FX Editor to load or save presets for reuse.
• To load a preset: Open the FX Editor, select a preset from the Presets panel, and click Apply to return to the host application.
• To save a custom preset: While in the FX Editor, click the Create Custom Preset icon in the parameter list, enter a preset name, and click Done. Additionally, a custom preset can be saved from the main menu bar by selecting File->Save Preset.
• To import custom presets from another drive: While in the FX Editor, select File->Import Preset from the main menu bar.

Effect Controls

Mocha Mask and Track

Continuum effects include integrated masking and matte tools that allow you to restrict the effect to specific regions of the image.

• Mocha masks: used to create custom spline masks. Mocha also includes Matte Assist ML and Matte Refine ML, which use machine learning to generate and track masks.
• Pixel Chooser: used to generate geometric shapes, gradients, or mattes based on channel, luma, or color-based selections. Additionally, an AI depth map generator, and an AI-powered face detection model allow for precise control of masks and mattes.

For more information, see Mocha and Pixel Chooser.

Compare Mode

The Compare Mode is used to view the filtered result alongside the original source layer. Several split-screen and side-by-side display options are available.

For more information, see Compare Mode.

• View: Toggles the render view
• Output: Displays the final filtered output
• Matte: Displays the matte used for the key.
• Matte Invert: Displays an inverted matte used for the key.
• Mask Transparent Pixels: Displays a color overlay to identify transparent pixels.
• Channel: 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.
• 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.
• 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.
• Softness: Used to soften the matte by increasing transparency in pixels that are close to the borders of the key color 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.
• 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.

Region Group

• Region of Interest: Determines the shape of the region in which the filter is applied.
• Inside Rectangle: Confines the filter result to the region inside the rectangle shape bounds
• Outside Rectangle: Confines the filter result to the region outside the rectangle shape bounds
• Inside Oval: Confines the filter result to the region inside the oval shape bounds
• Outside Oval: Confines the filter result to the region inside the oval shape bounds
• All: ROI is bypassed and the entire image source is included in the key matte generation
• 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.
• Crop: Preexisting alpha channel values are cropped to within the ROI
• Use Existing Alpha: Existing alpha channel values outside of the ROI are preserved
• GPU Rendering:Specifies how the effect is rendered.
• Default: Uses product-wide default of 16 bit half-float GPU rendering.
• 16 Bit Float: Manually force 16 bit half-float GPU rendering.
• 32 Bit Float: Manually force 32 bit full-float GPU rendering.
• Disabled: Forces CPU rendering.