how to create mask in after effects

You can create one or more masks for each layer in a composition using any of the following methods:

Draw a path using the shape tools or Pen tool. Drawing a mask path is similar to drawing a shape path. (See Create a shape or mask by dragging with shape tools and Create a Bezier shape or mask using the Pen tool.)
Specify the dimensions of the mask path numerically in the Mask Shape dialog box. (See Create a rectangular or elliptical mask numerically.)
Convert a shape path to a mask path by copying the shape's path to the Mask Path property.
Convert a motion path to a mask path. (See Create a mask or shape from a motion path.)
Trace color or alpha channel values to create a mask using the Auto-trace command. (See Create a mask from a channel with Auto-trace.)
Paste a path copied from another layer or from Adobe Illustrator, Photoshop, or Fireworks. (See Copy a path from Illustrator, Photoshop, or Fireworks.)
Convert a text layer to one or more editable masks on a solid-color layer by using the Create Masks From Text command. (See Create shapes or masks from text characters.)
Use captured shapes to create motion graphics. (See Use captured shapes to create motion graphics.)

When you create masks on a layer, the mask names appear in the Timeline panel outline in the order in which you create the masks. To organize and keep track of your masks, rename them.

Note:

To rename a mask, select it and press Enter (Windows) or Return (Mac OS), or right-click (Windows) or Control-click (Mac OS) the mask name and choose Rename.

When creating additional masks for one layer in the Layer panel, make sure that the Target menu in the Layer panel is set to None; otherwise, you replace the targeted mask instead of creating a mask. You can also lock a mask to prevent changes to it.

Menu selections to specify a mask to target in the Layer panel

A. View menuB. Target menu

When creating or editing masks, look in the Info panel for information such as the mask name and the number of vertices in the mask.

Note:

To create a mask that you can move independently of the primary layer that it is masking, do the following:

Create the mask on a separate white solid layer, and use that solid layer as a track matte for the primary layer.
Use parenting to make the solid layer a child of the primary layer, so that the mask moves with the primary layer as if it were applied directly. Because the solid layer is a child layer, it can also be animated independently of its parent.
You can use motion tracking to make the solid layer (and therefore the mask) follow moving objects in the primary layer. (See Convert a layer into a track matte and Parent and child layers.)

Select a layer in the Composition panel, or display a layer in the Layer panel.

Choose Layer > Mask > New Mask. A new mask appears in the Composition or Layer panel with its handles at the outer edges of the frame.

Choose Layer > Mask > Mask Shape.

Select Reset To, choose Rectangle or Ellipse from the Shape menu, and specify the size and location of the bounding box for the mask.

You can convert the alpha, red, green, blue, or luminance channel of a layer to one or more masks by using the Auto-trace command.
Auto-trace creates as many Bezier masks as necessary to outline the specified channel values in the layer.
It also creates masks with the smallest number of vertices possible while conforming to the settings that you choose.
You can modify a mask created with Auto-trace as you would any other mask, and you can link its path to other path types, such as shape paths on a shape layer, using expressions.

When you apply Auto-trace, affected layers are automatically set to Best Quality to ensure accurate results.

Note:

To reduce the number of masks created by Auto-trace, apply a keying effect to the layer to isolate your subject before applying Auto-trace.

In the Timeline panel, do one of the following:

To create mask keyframes at a single frame, drag the current-time indicator to the desired frame.

To create mask keyframes across a range of frames, set a work area that spans that range.

Select one or more layers.

Choose Layer > Auto-trace.

Select one of the following:

Current Frame

Creates mask keyframes at only the current frame.

Work Area

Creates mask keyframes for frames within the work area.

Set any of the following options:

Invert

Inverts the input layer before searching for edges.

Blur

Blurs the original image before generating the tracing result. Select this option to reduce small artifacts and to smooth jagged edges in the tracing result. Deselect this option to closely trace details in a high-contrast image. Specify the radius, in pixels, of the area used for the blurring operation. Larger values result in more blur.

Tolerance

How far, in pixels, the traced path is allowed to deviate from the contours of the channel.

Threshold

Specifies, as a percentage, the value that a pixel's channel must have for that pixel to be considered part of an edge. Pixels with channel values over the threshold are mapped to white and are opaque; pixels with values under the threshold are mapped to black and are transparent.

Minimum Area

Specifies the smallest feature in the original image that is traced. For example, a value of 4 removes features smaller than 2 pixels wide by 2 pixels high from the tracing result.

Corner Roundness

Specifies the roundness of the mask curve at vertices. Enter a higher value for smoother curves.

Apply To New Layer

Applies the mask to a new solid the same size as the selected layer. This control is automatically selected for layers that have Collapse Transformations enabled—it creates a layer the same size as the composition that contains the layer.

Preview

Select to preview the mask results and the results of the various options of the Auto-trace command.

You create a shape layer by drawing in the Composition panel with a shape tool or the Pen tool. You can then add shape attributes to existing shapes or create shapes within that shape layer. By default, if you draw in the Composition panel when a shape layer is selected, you create a shape within that shape layer, above the selected shapes or group of shapes. If you draw in the Composition panel using a shape tool or Pen tool when an image layer other than a shape layer is selected, you create a mask.

Note:

Before drawing in the Composition panel to create a shape layer, press F2 and deselect all layers.

You can create shapes and shape layers using any of the following methods:

Draw a path using the shape tools or Pen tool. Drawing a mask path is similar to drawing a shape path. (See Create a shape or mask by dragging with shape tools and Create a Bezier shape or mask using the Pen tool.)
Convert a text layer to shapes on a shape layer by using the Create Shapes From Text command. (See Create shapes or masks from text characters.)
Convert a mask path to a shape path.
Convert a motion path to a shape path. (See Create a mask or shape from a motion path.)
Paste a path copied from another layer or from Adobe Illustrator, Photoshop, or Fireworks. (See Copy a path from Illustrator, Photoshop, or Fireworks.)
Create an empty shape layer by choosing Layer > New > Shape Layer.

Usually, a new shape has a fill and a stroke that correspond to the Fill and Stroke settings in the Tools panel at the time that the shape is drawn. You can use the same controls in the Tools panel to change these attributes for a selected shape after it has been drawn. Shapes created from text are created with fills and strokes that match the fills and strokes of the original text.

Note:

To draw a mask on a shape layer, click the Tool Creates Mask button in the Tools panel with a shape tool or Pen tool active. For more information about creating masks, see Creating masks.

In previous versions of After Effects, you could import an Illustrator (.ai), EPS (.eps), or PDF (.pdf) file, however you could not modify the file. Now you can create a shape layer from a vector art footage layer, and then modify it.

With the ability to bevel and extrude objects in After Effects, you can extrude the artwork (for example, extruded logos), as well. See Extruding text and shape layers.

To convert a vector art footage layer to shape layer:

Choose Layer > Create Shapes from Vector Layer. A matching shape layer appears above the footage layer, and the footage layer is muted.

The following issues are known:

Not all features of Illustrator files are currently preserved. Examples include: opacity, images, and gradients.
Converted shapes ignore PAR overrides specified in the Interpret Footage dialog box.
Gradients and unsupported types may show as 50% gray shapes.
Files with thousands of paths may import slowly without feedback.
The menu command works on a single selected layer at a time.
If you import an Illustrator file as a composition (i.e., several layers), you cannot convert all those layers in one pass. However, you can import the file as footage, and then use the command to convert the single footage layer to shapes.

In this video by Todd Kopriva and video2brain, see how to quickly convert vector graphics from Illustrator to shape layers and animate the paths in After Effects CS6. This process is much simpler than in previous versions of After Effects.

Note:

To activate and cycle through the shape tools, press Q.

A polygon is a star without an Inner Radius or Inner Roundness property. So, the name of the shape created for a polygon or a star is the same: polystar.

You can create a mask by dragging with a shape tool on a selected layer in the Composition panel or Layer panel. You can create a shape by dragging with a shape tool on a selected shape layer in the Composition panel. If you drag with a shape tool in the Composition panel with no layer selected, you create a shape on a new shape layer.

Note:

To draw a mask on a shape layer, click the Tool Creates Mask button in the Tools panel with a shape tool active.

When you create a shape by dragging with a shape tool in the Composition panel, you create a parametric shape path. To instead create a Bezier shape path, press the Alt (Windows) or Option (Mac OS) key before you click to begin dragging. You can release the key before you complete the drag operation. All mask paths are Bezier paths. (See About shapes and shape layers.)

Dragging starts when you click in the Composition panel or Layer panel to begin drawing, and ends when you release the mouse button. Pressing modifier keys at different times during a single dragging operation achieves different results:

To reposition a shape or mask as you are drawing, hold the spacebar or the middle mouse button while dragging.
To scale a circle, ellipse, square, rounded square, rectangle, or rounded rectangle around its center while drawing, hold the Ctrl (Windows) or Command (Mac OS) key after you begin dragging. Don't release the key until you have released the mouse button to finish drawing.
To cancel the drawing operation, press Esc.

Note:

Each shape tool retains the settings of the most recent drawing operation with that tool. For example, if you draw a star and modify the number of points to be 10, then the next star that you draw will also have 10 points. To reset settings for a tool and create a shape with the default settings, double-click the tool in the Tools panel. (See Create a shape or mask the size of the layer.)

Select the Rectangle tool or the Rounded Rectangle tool , and do one of the following:

To draw a rectangle or rounded rectangle, drag diagonally.

To draw a square or rounded square, Shift-drag diagonally.

(Optional) If drawing a rounded rectangle or rounded square, do the following before releasing the mouse button:

To increase or decrease the corner roundness, press the Up arrow key or the Down arrow key, or roll the mousewheel forward or backward.

To set corner roundness to the minimum or maximum, press the Left arrow key or the Right arrow key.

Finish drawing by releasing the mouse button. If drawing a square or rounded square, release the Shift key after releasing the mouse button.

Note:

Squares are created to be square according to the pixel aspect ratio of the composition. If the pixel aspect ratio of the composition is not 1, then squares appear square in the Composition panel only if the Toggle Pixel Aspect Ratio button is selected at the bottom of the Composition panel.

Select the Ellipse tool , and do one of the following:

To draw an ellipse, drag diagonally.

To draw a circle, Shift-drag diagonally.

Release the mouse button to finish drawing. If drawing a circle, release the Shift key after releasing the mouse button.

Note:

Circles are created to be circular according to the pixel aspect ratio of the composition. If the pixel aspect ratio of the composition is not 1, then circles appear circular in the Composition panel only if the Toggle Pixel Aspect Ratio button is selected at the bottom of the Composition panel.

Select the Polygon tool or the Star tool , and do one of the following:

Drag to scale and rotate the polygon or star as you draw it.

Shift-drag to scale the polygon or star as you draw it, preventing rotation.

(Optional) Do the following before releasing the mouse button:

To add or remove points, press the Up arrow key or the Down arrow key, or roll the mouse wheel forward or backward.

To increase or decrease the outer roundness, press the Left arrow key or the Right arrow key.

To keep the inner radius of a star constant as you move the mouse to increase the outer radius, hold the Ctrl (Windows) or Command (Mac OS) key.

To increase or decrease the inner roundness of a star, press the Page Up key or the Page Down key.

Release the mouse button to finish drawing. If Shift-dragging to prevent rotation, release the Shift key after releasing the mouse button.

You can create a Bezier mask using the Pen tool on a selected layer in the Composition panel or Layer panel. You can create a shape with a Bezier path using the Pen tool on a selected shape layer in the Composition panel. If you draw with the Pen tool in the Composition panel with no layer selected, you create a shape on a new shape layer.

Creating a RotoBezier path is similar to creating a manual Bezier path. The primary difference is that direction lines for vertices and curvature for path segments are automatically calculated.

With the Pen tool selected and the RotoBezier option deselected in the Tools panel, click in the Composition panel where you want to place the first vertex.

Click where you want to place the next vertex. To create a curved segment, drag the direction line handle to create the curve that you want.

Note:

To reposition a vertex after you've clicked to place it but before you've released the mouse button, hold the spacebar while dragging.

The last vertex that you add appears as a solid square, indicating that it is selected. Previously added vertices become hollow, and deselected, as you add more vertices.

Repeat step 2 until you are ready to complete the path.

Complete the path by doing one of the following:

To close the path, place the pointer over the first vertex and, when a closed circle icon appears next to the pointer , click the vertex.

Note:

You can also close a path by double-clicking the last vertex or choosing Layer > Mask And Shape Path > Closed.

To leave the path open, activate a different tool, or press F2 to deselect the path.

The simplest path that you can draw with the Pen tool is a straight line, made by clicking with the Pen tool to create two vertices. By continuing to click, you create a path made of straight-line segments connected by corner points.

Clicking with Pen tool creates straight segments

Clicking with Pen tool creates straight segments.

Place the Pen tool where you want the straight segment to begin, and click to place a vertex. (Do not drag.)

Click again where you want the segment to end. (Shift-click to constrain the angle between segments at the corner point to a whole multiple of 45°.)

Continue clicking to set vertices for additional straight segments.

You create a curved path segment by dragging direction lines. The length and direction of the direction lines determine the shape of the curve.

Note:

Shift-drag to constrain the angle of the direction lines to whole multiples of 45°. Alt-drag (Windows) or Option-drag (Mac OS) to modify only the outgoing direction line.

Place the Pen tool where you want the curve to begin, and hold the mouse button down.

A vertex appears, and the Pen tool pointer changes to an arrowhead.

Drag to modify the length and direction of both direction lines for a vertex, and then release the mouse button.

Drawing the first vertex in a curved path

A. Placing the Pen toolB. Starting to drag (mouse button pressed)C. Dragging to extend direction lines

Place the Pen tool where you want the curved segment to end, and do one of the following:

To create a C-shaped curve, drag in the direction opposite from the direction that you dragged the previous direction line, and then release the mouse button.

Drawing the second vertex in a curved path

A. Starting to dragB. Dragging away from previous direction line, creating a C curveC. Result after releasing mouse button

To create an S-shaped curve, drag in the same direction as the previous direction line, and then release the mouse button.

Drawing an S curve

A. Starting to dragB. Dragging in same direction as previous direction line, creating an S curveC. Result after releasing mouse button

Continue dragging the Pen tool from different locations to create a series of smooth curves.

Select the destination for the new mask or shape:

To create a shape on an existing shape layer, select the shape layer.

To create a shape on a new shape layer with the dimensions of the composition, deselect all layers by pressing F2.

To create a mask, select a layer in the Timeline panel, Layer panel, or Composition panel. To create a mask on a shape layer, select Tool Creates Mask in the Tools panel with a shape tool active.

To replace a mask path, select the mask in the Timeline panel, Layer panel, or Composition panel.

To replace a shape path, select the shape path (not the group) in the Composition panel or Timeline panel.

The Create Shapes From Text command extracts the outlines for each character, creates shapes from the outlines, and puts the shapes on a new shape layer. You can then use these shapes as you would any other shapes.

The Create Masks From Text command extracts the outlines for each character, creates masks from the outlines, and puts the masks on a new solid-color layer. You can then use these masks as you would any other masks.

Note:

Some font families, such as Webdings, include characters that are graphical images, rather than text. Converting text from these font families can be a good way to get started with simple graphical elements in shape layers.

Select the text to convert to shapes:

To create shapes for all characters in a text layer, select the text layer in the Timeline panel or Composition panel.

To create shapes for specific characters, select the characters in the Composition panel.

Choose Layer > Create Shapes From Text.

Right-click (Windows) or Control-click (Mac OS) the layer or text and choose Create Shapes From Text from the context menu.

The Video switch for the text layer is turned off.

The new shape layer is created at the top of the layer stacking order. The new layer contains one shape group for each selected character, plus fill and stroke properties that match the fills and strokes of the text.

For characters that consist of compound paths—such as i and e—multiple paths are created and combined with the Merge Paths path operation.

Effects, masks, layer styles, and keyframes and expressions for properties in the Transform property group of the text layer are copied to the new shape layer or solid-color layer.

Select the text to convert to masks:

To create masks for all characters in a text layer, select the text layer in the Timeline panel or Composition panel.

To create masks for specific characters, select the characters in the Composition panel.

Choose Layer > Create Masks From Text.

Right-click (Windows) or Control-click (Mac OS) the layer or text and choose Create Masks From Text from the context menu.

The Video switch for the text layer is turned off.

The new solid-color layer is created at the top of the layer stacking order.

For characters that consist of compound paths—such as i and e—multiple masks are created and combined with the Subtract mask mode.

You can copy a path from Illustrator, Photoshop, or Fireworks and paste it into After Effects as a mask path or shape path.

To make the data copied from Illustrator compatible with After Effects, the AICB option must be selected in the Files & Clipboard section of the Adobe Illustrator Preferences dialog box.

For a path imported from Photoshop to be scaled correctly, the Photoshop document must have a resolution of 72 dpi. 72 dpi is the Resolution setting of documents created in Photoshop using a Film & Video preset.

Note:You can also use a copied Illustrator, Photoshop, or Fireworks path as an After Effects motion path. See Create a motion path from a mask, shape, or paint path for more information.

Path drawn in Adobe Illustrator (left) and pasted into After Effects as a mask (right)

In Illustrator, Photoshop, or Fireworks, select an entire path, and then choose Edit > Copy.

In After Effects, do one of the following to define a target for the paste operation:

To create a mask, select a layer.

To replace an existing mask path or shape path, select its Path property.

Note:

To paste a path as a shape path, you must select the Path property of an existing shape in a shape layer. This selection tells After Effects what the target of the paste operation is; if the target isn't specified in this way, After Effects assumes that the target is the entire layer and therefore draws a new mask. If there is no Path property—perhaps because the shape layer is empty—then you can draw a placeholder path with the Pen tool and then paste the path from Illustrator into the placeholder path.

If you paste multiple paths into a shape path, the first path goes into the shape path, and the remaining paths are pasted into new mask paths. This behavior is because the paths other than the first one don't have a clearly defined target, so they are added to the entire layer as masks.

Andrew Devis shows how to use paths from Illustrator as motion paths in After Effects in this video on the Creative COW website.

You can copy position keyframes, anchor point keyframes, or an effect control point's position keyframes and paste those keyframes into a selected mask path or shape path. When you create mask paths or shape paths from motion paths, make sure that you copy keyframes from a single Position property only—do not copy the keyframes of any other property.

Note:

Draw a motion path with Motion Sketch and then paste the path into a mask path or shape path.

Create a mask or shape from a motion path

The motion path of the spaceship (top) is copied to the background layer (lower-left) and used by the Vegas effect (lower-right).

Note:

When copying between a mask path to a motion path, keep in mind that the mask path's values are expressed in the coordinate system of the layer (layer space), whereas the motion path's values are expressed in the coordinate system of the composition (composition space). This difference causes the pasted path to be offset, requiring you to reposition the path after pasting it. (See Coordinate systems: composition space and layer space.)

In the Timeline panel, click the name of the Position property or Anchor Point property from which you want to copy the motion path. (This selects all keyframes. To select only some of the keyframes of a motion path, Shift-click them.)

To create a mask, select the layer on which to create the mask, and choose Layer > Mask > New Mask.

In the Timeline panel, click the name of the Mask Path property for the mask into which to paste the keyframes from the motion path.

Selecting and copying Position keyframes

Selecting and copying Position keyframes (left); then pasting them in the selected Mask Path property (right)

To create a shape layer, press F2 to deselect all layers, then click in the Composition panel with the Pen tool to create a single-point Bezier path.

Press SS to reveal the Path property for the shape. Click the name of the Path property into which to paste the keyframes from the motion path.

When a shape group is selected in group selection mode, you can duplicate the group while moving, rotating, or scaling it in the Composition panel.

Hold the Alt (Windows) or Option (Mac OS) key as you drag to transform a group.
The pointer changes to a duplication pointer ( or ) as you hold the key and place the pointer near the group transform box.