Masks

A mask limits where a node acts. Without one, an Adjustment, Text, Heal or Frequency Separation node changes the whole frame; with one, its change comes through only where the mask admits it. A mask is built from components: gradients, a rectangle, brush strokes, a luma or color range, the subject of the picture, or a key borrowed from another node. The components are listed on the Mix tab and drawn on the loupe in mask mode. This chapter covers both, and how masks are copied and shared between nodes.

The four node kinds above are the maskable ones. An input node cannot carry a mask; asking for one there inserts a masked Adjustment after it instead. A Parallel or Layer node has a Mix tab of its own kind, covered in Chapter 15. Following a mask through a clip is Chapter 23.

19.1 Where a mask lives

Where to find it: the Mix tab, with a maskable node selected.

The Mix tab opens with the node’s STRENGTH slider, 0 % to 100 %, which is the node’s opacity as a whole. Below it, COMPONENTS lists the mask, and two further sections follow as the selection calls for them: COMPONENT, for the component selected in the list, and MASK, for settings that apply to the finished mask. The footer under the tab states the rule: strength and mask together decide how much of the node’s change comes through, and 0 % strength is the same as disabling the node. With no maskable node selected the tab reads Select a maskable node.

On the node canvas a maskable card shows a small badge at its top-right corner once its mask has a component: a filled dot when the mask has components of its own, a ring when it consists only of keys from other nodes, and a dot inside a ring for both. The badge dims when the mask is effectively empty, that is, every component is switched off or Density is at zero. Clicking the badge selects the node and opens the Mix tab.

The card’s right-click menu carries Add Mask on a node without one and Edit Mask on a node with one; both select the node and open the Mix tab. The other mask commands are covered in 19.9 and 19.10.

19.2 Mask mode on the loupe

Where to find it: the Mix tab arms it; the M key from the loupe opens the tab and arms it.

While the Mix tab is active on a maskable node the loupe is in mask mode. The region the mask admits is tinted red over the picture. O hides and shows the tint; ⇧O cycles its style through three looks: the red tint, the mask alone as white on black, and the picture where the mask admits it with black elsewhere. The tint fades while any slider other than the mask’s own is dragged, so the adjustment can be judged, and returns on release.

The selected component is drawn over the picture in the mask color, with grips where it can be reshaped; the table in 19.3 says what each kind draws. Only the selected component is drawn, so selecting a row in the COMPONENTS list, or clicking the row again to deselect it, changes what the loupe shows. Grips stay grabbable even when a tracked component has carried them outside the picture. ⇧⌘H hides the handles and outlines together with the tint, and pressing it again brings both back.

Mask mode starts with no tool armed, so a drag on the picture pans as usual. B, G, R and A arm the brush, the linear gradient, the radial gradient and the subject tool; Esc disarms the tool, and a second Esc deselects the component. On a clip, Esc first stops a tracking pass if one is running. An undo or redo leaves the inspector on the Mix tab, so mask mode stays on while mask edits are stepped back.

M works only while mask mode is off. Pressed on an unmaskable node, a Colour Space node for instance, it inserts a masked Adjustment after that node and opens its Mix tab. The same happens if a mask gesture lands on such a node.

19.3 Components and how they combine

A mask is an ordered list. The first component sets the starting shape; each subsequent component changes the mask according to its row’s operation: + adds its area, − takes its area away, ∩ keeps only where both overlap. The row’s operation menu is disabled on the first row, since there is nothing before it to combine with. Change a later row’s operation to reshape the whole mask without redrawing anything.

Each row carries a checkbox, an icon for the kind, a name, the operation menu and a trash button. Names are the kind and the row’s position in the list, Linear Gradient 1, Brush 2, so deleting a row renumbers those below it. A key from another node reads Key from and that node’s name. Unticking the checkbox excludes the component from the mask and grays its row; undo Edit Mask Component. The trash button, or ⌫ with the loupe in front, deletes the selected row; undo Delete Mask Component. Clicking a row selects it and opens the COMPONENT section; clicking the selected row deselects it. With no components the list says so and points at the buttons below it.

Two rows of buttons under the list add one component each, selected and ready to edit: Linear, Radial, Rect, Brush on the first row, Luma, Color, AI on the second, with Skin beside them on a Frequency Separation node only. The first component on a node without a mask records the undo Add Mask; later ones record Add Linear Gradient, Add Radial Gradient, Add Rectangle, Add Brush, Add Luma Range, Add Color Range or Add AI Subject.

An unrecognized component appears as Unsupported, with its original kind in parentheses. It cannot be edited.

19.4 Gradients and rectangles

With G armed, drag across the picture: the gradient runs from where the drag began to where it ended, fully admitting the mask on the start side and fading to nothing past the end. With R armed, drag from the center outward; the gradient admits the mask at the center and fades to the edge of a circle whose radius is the drag. A rectangle is added from the tab, centered in the frame, and then shaped by its grips. All three can also be added from the tab at a default position and placed afterward.

Drag a grip to reshape: the two ends of a linear gradient; the center, x radius and y radius of a radial one; the center, width and height of a rectangle. Undo Move Mask Component.

The COMPONENT section offers, for every selected component, Invert Component (undo Invert Mask Component) and Feather, 0.0 % to 10.0 %, which softens the component’s edge (undo Set Mask Feather). A radial gradient adds Softness, 0 % to 100 %, the share of the radius over which it fades, and Rotation, −180° to 180°; a rectangle adds Rotation alone.

19.5 The brush

With B armed, drag on the picture to paint. A circle follows the pointer at the brush size, and the stroke appears in the mask color as it is laid. ⌥-drag erases through earlier strokes. Strokes go to the selected brush component, or to the most recent enabled brush when none is selected; with no brush in the mask the first stroke creates one. Undo Paint Mask Stroke or Erase Mask Stroke.

[ and ] shrink and grow the brush; the Size row in the COMPONENT section sets it directly, 0.2 % to 15.0 % of the picture’s width, 5.0 % to start. The size applies to the next stroke, not to strokes already painted.

A brush component has no grips: it is painted, not dragged. On a clip whose brush is tracked, a single grip appears at the brush’s reference point for correcting the track, which Chapter 23 covers.

19.6 Luma and color ranges

A range component admits the mask where the picture’s own values fall inside a band: brightness for a Luma Range, hue, saturation and brightness together for a Color Range. Add one from the tab, or choose its starting range from the picture: ⌥-click a pixel for a luma range centered on its brightness, ⌥⇧-click for a color range centered on its color. With the brush armed, ⌥-click still creates a luma range; drag to erase. Changes to preceding nodes can change the area a range selects.

The COMPONENT section shows a strip for each axis. A Luma Range has one, Range; a Color Range has Hue, Saturation and Luma. Each strip draws the band over a gradient of the axis: a filled body between two edges, with a soft fringe fading outward from each edge. Drag the body to move the band, an edge to set that bound, a fringe to set how softly that edge falls off. A Luma Range softens each edge on its own; a Color Range has one softness, so dragging any of its fringes softens every edge on all three strips.

On the Hue strip the two edges move together, widening or narrowing the band evenly about its center. The Hue strip wraps, so a band across red is drawn as two segments and drags continuously through 0°. The Saturation strip’s gradient takes on the hue at the band’s center, so it previews the colors it is selecting.

An edge of the color range’s Luma strip parked at the strip’s end is unbounded: no limit on that side. It is drawn as a dashed marker just inside the end so it can still be grabbed and dragged inward.

Double-click any strip to show or hide numeric rows under it, for precision. A Luma Range offers Low, High, Soften Low and Soften High; a Color Range offers Hue, Hue Range (shown as plus or minus degrees), Sat Low, Sat High, Luma Low, Luma High and Softness. Low and high values clamp against each other, so a band can narrow to a point but never cross. Every strip and numeric change records the undo Set Mask Range.

Note: Ranges update on every frame of a clip. They do not need or offer tracking.

19.7 The subject component

The AI button adds a subject component, which selects the main subject of a still from a few points you place. Press A to arm the subject tool. If the component is still empty when the tool is armed, Revela finds the subject on its own and places the seed points for you. If the picture has no subject, nothing is placed and the hint line under the component says to click the subject. Click the subject to select it, or to add another whole object; ⌥-click to exclude an area. Each click places a marker, a circle for an add point and a square for an exclude point, and the selection updates around the new set.

Click a marker to remove it; drag one to move it, previewing the result as you drag; ⌫ removes the marker last dragged. The hint line under the component counts the add and exclude points and restates the gestures. Undo records Add Seed Point, Add Exclude Point, Move Seed Point, Remove Seed Point and, for the automatic selection, Select Subject. When the selection cannot be made, for instance because the original is offline, the alert Could Not Select the Subject says why.

The subject component selects whole objects, not edges. To refine it, add a Brush or another component set to − or ∩ after it, as the hint suggests.

Note: the subject component is available on stills only. On a clip the AI button is disabled with a caption beneath it saying so, and A beeps.

19.8 Skin

Where to find it: the Mix tab of a Frequency Separation node, the Skin button.

Skin adds a mask for the subject’s skin, excluding similarly colored surroundings. The list shows a Color Range with the ∩ operation and an AI Subject component. On a clip, or when no subject is found, only the Color Range is added. Undo Add Skin Mask. Edit these components as described in 19.6 and 19.7.

19.9 The whole mask

The MASK section appears once the node has a mask. Feather, 0.0 % to 10.0 %, softens the finished mask’s edges (undo Set Mask Feather). Density, 0 % to 100 %, caps how strongly the mask admits the node anywhere, so a mask at 50 % density lets half the node’s change through at its fullest (undo Set Mask Density). Invert Mask swaps admitted and excluded for the whole mask (undo Invert Mask), and Remove Mask discards it, components and all (undo Remove Mask).

The card’s right-click menu offers Invert Mask and Remove Mask as well, and one more verb: Add Inverted Copy After inserts a new Adjustment after the node carrying a copy of its mask with the inversion toggled, so one mask can govern two opposite treatments. Keys from other nodes are not carried into the copy. Undo Add Inverted Mask Copy.

Resetting a node (Chapter 11) removes its mask along with every key wire into and out of it.

19.10 Copying and sharing masks

Where to find it: right-click a maskable card on the node canvas.

Copy and paste. Copy Mask keeps a copy of the node’s mask for use in any open Catalogue window. Copying text or an image does not replace it; copying another mask does. Paste Mask appears on any maskable card while a mask is held and replaces that node’s mask with the copy, creating one if the node had none (undo Paste Mask). Keys from other nodes are dropped from the paste, because no wire travels with it. These commands are unavailable from the menu bar.

Sharing as a key. Rather than copying a mask, one node can use another’s mask as a key. The receiving node gains an External Key component whose row reads Key from and the source node’s name, and the two cards are joined by a key wire, drawn in the mask color and dipping below the cards so it reads apart from the image wires. The key carries the source node’s mask with its Feather and inversion; the source’s Density stays with the source node. The key updates whenever the source changes. In the receiving mask it combines like any other component, with its own operation, Invert Component and Feather.

To share, right-click the receiving card and choose Use Mask From, then the source by name; the list offers every node whose mask can be shared here, left to right as drawn. Or drag from the source card’s key output port, at the right of its bottom edge, onto the receiving card; the ports appear as the pointer nears a maskable card’s bottom edge. ⌥-dragging a card’s mask badge starts the same drag. Undo Connect Mask Key.

Selecting the key’s row shows a Source row naming the node it comes from and a Disconnect button. Disconnect Mask Key on the receiving card does the same; with several keys landing on one node it opens a submenu of their sources. Dragging the wire away from the receiving card’s key input port detaches it: drop it on another node that can supply a key to re-source it (undo Rewire Mask Key), or on empty canvas to disconnect (undo Disconnect Mask Key). Dropped on a card that cannot supply a key, or back on the port it came from, the wire stays as it was.

A mask can feed any number of nodes, and a node can take keys from several; a share that would form a loop is not offered. Pasting a copied node (Chapter 11) leaves its keys behind, as Paste Mask does, and says so. How a Layer node reads the masks of its inputs is in Chapter 15.

19.11 Masks on video

On a clip the gradient, rectangle and brush components can follow motion. Selecting one adds a TRACKING section to the Mix tab with Track motion and a status line. Once Track motion is on, the section adds Follow, a transport, a lifetime and Reset Tracking, with a re-track button on a keyframe or after a failed pass, and a lane appears on the scrubber for the selected component’s track. Ranges update on every frame without tracking. A shared key follows its source node’s track. Subject components are available only on stills. Tracking, keyframes, correction drags and the lane are covered once for masks, heals and frequency separation in Chapter 23.

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