Composite Brush is a color selector and modifier for After Effects, developed by Vranos. You work by painting on the footage: click and drag to assign selected (positive) colors, and use a modifier-click to assign unselected (negative) colors. With a few strokes you can build a selection, then modify colors, adjust the alpha channel, or pull a key.
Selected colors are processed through transfer modes. Hue, Saturation, and Luminance copy those attributes from a transfer-mode color into the selection, Normal copies the color over it, and HSV combines hue with saturation and lightness. Alpha operations include Increase Alpha, Stencil Alpha, and Silhouette Alpha, while Restore Original RGB and Restore Original RGBA bring back the source image inside the selection.
Matte types control edge falloff, from a fast Hard mode to Medium, Soft, a Hair mode aimed at soft edges on hair, glass, smoke, and fire, and a later Soft 1.6 type. Refinement controls include Precision, Matte High and Low Level, Matte Blur, Matte Choke, and Matte Invert. It is compatible with After Effects CC 2019 through 2025.