Constant

The Constant Image Generator fills an area with a single color. By default it fills everything, which makes it the simplest way to create a solid background. Give it a format, and it becomes a rectangle that you can turn into a frame, round at the corners, soften or invert, procedurally and at any resolution.

Use it for:

• Solid backgrounds and color plates
• Rectangles, bars, frames and rounded boxes
• Vignettes and soft-edged rectangular masks
• Rectangular gradients that follow the shape, with the Distance Field mode

Quick Navigation

• Creating and Connecting a Constant
• Solid Color or Rectangle: the Output Format
• Fill, Frame or Gradient: the Edge Mode
• Keeping Proportions with the Size Scaled Modes
• Rounded Corners
• Soft Edges with Feather
• Creating a Vignette
• Motion Blur
• Controls

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Creating and Connecting a Constant

Like any Image Generator, the Constant can be connected to any image parameter, for example:

• The Source of a layer, to display the color or the rectangle itself
• The Mask of a layer, to reveal that layer through a rectangle, a rounded box or a soft frame
• The image input of a Modifier, for example to use the rectangle as a matte

The quickest way to create a layer with a Constant as its source is described in Adding Layers:

• Click the + button at the top of the layer stack and choose Constant from the list of Generators
• Place the mouse cursor over the Viewer and open the Quick Access Menu, then pick Constant:
  • Press Q when no layer is selected
  • Press Shift+Q when a layer is selected (in this case, Q opens the menu dedicated to Modifiers)

To use it with any other image parameter, such as a Mask, click the parameter's slot and choose Constant from the list of Generators on the right.

Solid Color or Rectangle: the Output Format

Unlike the Circle, the Constant has no size or position parameters of its own: its shape is its Output Format.

• Unbounded (the default): the color fills the whole, infinite canvas. Use it for solid backgrounds.
• Composition Format: a rectangle with the exact size of the composition.
• Format Preset: a rectangle with the size of the selected preset, such as Square 512, centered in the composition.
• Custom Format: a rectangle you define with the Format parameter, as its left, bottom, right and top edges, in pixels from the center of the composition.

Fill, Frame or Gradient: the Edge Mode

The Edge Mode menu decides whether the rectangle is filled, drawn as a frame, or turned into a gradient. Figure 1 shows the four main modes; the two Size Scaled modes are frames, shown in Figure 2.

• None: draws a filled rectangle.
• Inner Size: cuts a rectangular hole in the middle. Inner Size is the width and height of the hole, in pixels: an Inner Size of 240 × 100 leaves a 240 by 100 pixel hole at the center.
• Thickness: draws a frame of the given Thickness, centered on the edges of the rectangle: half of the frame is drawn outside the Format rectangle and half inside.
• Distance Field: fills the rectangle with a gradient based on the distance to its nearest edge, transparent at the edges and full color at the center. See Distance Field below.
• Size Scaled Thickness: draws a frame like Thickness, but the Thickness is a percentage of the rectangle's size, so the frame keeps its proportions when the rectangle is resized. See Keeping Proportions with the Size Scaled Modes.
• Size Scaled Thickness & Feather: same as Size Scaled Thickness, and the Feather sizes are scaled too.

Thickness and Inner Size have two values, one for the horizontal (X) and one for the vertical (Y) direction. With Thickness, X sets the width of the left and right sides of the frame, and Y the height of the top and bottom sides.

Distance Field

In Distance Field mode, the opacity of each pixel depends on its distance to the nearest edge of the rectangle. Along the diagonals, the gradients from two sides meet, which gives a beveled, pyramid-like look. Use it as a soft rectangular matte, or for a quick embossed look.

The Normalize Distance Field option decides how the distance is stored in the pixels:

• On (the default): the opacity goes from 0 at the edges to 1 at the center of the rectangle, whatever its size, and the Color is applied on top. This is the gradient you see in Figure 1.
• Off: each pixel stores its actual distance to the nearest edge, in pixels, in all four channels. In a rectangle 300 pixels high, the values go from 0 at the edges up to about 150 at the center.

Autograph processes images in 32-bit floating point, so pixel values can go far above 1.0, or below 0.0. With Normalize Distance Field off, almost the whole rectangle is above 1.0 and the Viewer shows it as solid white, but the actual distances are still there. Use this mode when another effect or an expression needs real distances in pixels.

Keeping Proportions with the Size Scaled Modes

In Thickness mode, the frame keeps the same width in pixels whatever the size of the rectangle. When the rectangle is animated, a fixed thickness can look too heavy on a small rectangle and too thin on a large one.

The Size Scaled Thickness mode expresses the Thickness as a percentage of half the size of the rectangle, on each axis: with a Thickness of 20, the left and right sides are 20% of half the width, and the top and bottom sides 20% of half the height.

Because the scaling is done on each axis, the sides of a wide rectangle are thicker than its top and bottom. The Size Scaled Thickness & Feather mode also scales the Feather sizes, so a soft frame keeps the same look while its size is animated.

Rounded Corners

Roundness Outer rounds the outer corners of the rectangle. The value is in pixels, and the corner radius is half of it: a Roundness of 80 gives corners with a 40-pixel radius, whatever the size of the rectangle. A value equal to the height of the rectangle turns its short sides into half circles.

• Each corner separately: Roundness is a 4D parameter. Switch it to Unified or Separated mode to set a value per corner. In Separated mode, its dimensions are named x, y, z and w: x is the top-right corner, y the bottom-right, z the top-left and w the bottom-left.
• Frames: in the Inner Size and Thickness modes, Roundness Inner rounds the corners of the hole independently from the outer corners.

Soft Edges with Feather

Feather Outer Size softens the outer edge of the rectangle, and Feather Inner Size softens the inner edge of a frame. As with the Circle, the feather is centered on the edge, so the rectangle keeps the same apparent size while you soften it.

Creating a Vignette

The vignette trick of the Circle also works with the Constant, with a rectangular shape that follows the frame more closely:

1. Add a Constant layer on top of your composition.
2. Enable Invert, and set the Color to black.
3. Set the Output Format to Composition Format, so the rectangle matches the frame.
4. Increase Feather Outer Size to fade the darkening toward the center.
5. Increase Roundness Outer to round the corners of the vignette and remove the diagonal seams of the feather. The higher the value, the closer the vignette gets to an oval.

Motion Blur

When the rectangle changes quickly, because its Format or its other parameters are animated, the Constant can render its own motion blur. Increase Divisions to enable it: this is the number of samples taken during the shutter interval, and higher values give a smoother blur at the cost of render time. Shutter Angle sets the length of the blur, and Shutter Phase sets when the shutter opens relative to the current frame. See Motion Blur for more details.

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Controls

Parameter / Script Name	Type	Default	Function
Enabled / enabled	Boolean	On	Turns the Generator on or off. When off, the Generator produces an empty image.
Output Format / output_format_mode	Choice	Unbounded	Defines the area filled by the color. See Solid Color or Rectangle. - Unbounded: Fills the whole, infinite canvas. - Format Preset: A rectangle with the size of the selected preset, centered. - Composition Format: A rectangle with the size of the composition. - Custom Format: The rectangle defined by the Format parameter.
Format / format_preset	Choice	HD (1920x1080)	The format used when Output Format is set to Format Preset. - PC VIDEO (640x480) - NTSC (720x486:0.91) - PAL (720x576:1.09) - NTSC 16:9 (720x486:1.21) - PAL 16:9 (720x576:1.46) - QHD (960x540) - LHD (1280x720) - HD (1920x1080) - VHD (1080x1920) - UHD 4K (3840x2160) - VUHD 4K (2160x3840) - UHD 8K (7680x4320) - Super35 1K FULL AP (1024x778) - Cinemascope 1K (914x778:2.00) - Super35 2K FULL AP (2048x1556) - Cinemascope 2K (1828x1556:2.00) - DCP 2K (2048x1080) - Super35 4K FULL AP (4096x3112) - DCP 4K (4096x2160) - Square 256 (256x256) - Square 512 (512x512) - Square 1K (1024x1024) - Square 2K (2048x2048)
Format / formatRect	Float 4D	-500, -500, 500, 500	The rectangle used when Output Format is set to Custom Format, as left, bottom, right and top edges in pixels from the center of the composition.
Pixel aspect / par	Float	1	The pixel aspect ratio of the generated image.
Color / color	Color	1, 1, 1, 1	Color and opacity of the fill.
Colorspace / input_colorspace	Choice	Project Display Space	Only available when the composition's Color Management is set to OpenColorIO. The colorspace in which the colors of this Generator are expressed. - Project Working Space: The color is assumed to be expressed in the project working space - Project Display Space: The color is assumed to be expressed in the project display space
Edge Mode / edge_mode	Choice	None	Chooses between a filled rectangle, a frame and a gradient. See Fill, Frame or Gradient. - None: Draw a filled rectangle. - Distance Field: Fill the rectangle with a gradient based on the distance to its edges. - Inner Size: Cut a hole of the given size in the middle of the rectangle. - Thickness: Draw a frame of the given thickness, centered on the edges. - Size Scaled Thickness: Draw a frame whose thickness is a percentage of the rectangle's size. - Size Scaled Thickness & Feather: Same as Size Scaled Thickness, and also scale the feather sizes.
Thickness / thickness	Float 2D	10, 10	Frame thickness, centered on the edges: X for the left and right sides, Y for the top and bottom sides. In pixels in Thickness mode, and as a percentage of half the rectangle's size in the Size Scaled modes.
Inner Size / edge_size	Float 2D	10, 10	Width and height of the hole, in pixels. Only used in Inner Size mode.
Feather Outer Size / feather_outer_size	Float	0	Softness of the outer edge. The feather is centered on the edge.
Feather Inner Size / feather_inner_size	Float	0	Softness of the inner edge of a frame. Has no effect when Edge Mode is None.
Normalize Distance Field / normalize_df	Boolean	On	In Distance Field mode, when on, the opacity goes from 0 at the edges to 1 at the center. When off, each pixel stores its distance to the nearest edge in pixels, with values far above 1.0.
Roundness Outer / roundness_outer	Float 4D	0, 0, 0, 0	Rounds the outer corners, in pixels; the corner radius is half the value. One value per corner: x top-right, y bottom-right, z top-left, w bottom-left.
Roundness Inner / roundness_inner	Float 4D	0, 0, 0, 0	Rounds the corners of the hole in the Inner Size and Thickness modes, with the same units and corner order as Roundness Outer.
Invert / invert	Boolean	Off	Fills the area outside the rectangle instead of the inside. See Creating a Vignette.
Divisions / divisions	Float	1	The number of samples to use for the motion-blur. The higher the number is, the more accurate is the motion-blur when large motion is involved, but the slower it is to render.
Shutter Angle / shutterAngle	Float	180	The shutter angle controls the time period over which light can pass. A wider angle increases motion-blur
Shutter Phase / shutterPhaseType	Choice	Centered	- Centered: The shutter opens half the shutter duration before the current time and closes half the shutter duration after - Start: The shutter opens at the current time and closes after the shutter duration is elapsed - End: The shutter opens at the current time minus the shutter duration and closes at the current time - Custom: The shutter opens at the time determined by a custom phase: the phase is an offset on the shutter angle, assuming the shutter opens at 0
Custom Phase / customPhase	Float	-90	An offset to the shutter angle, assuming the shutter opens at 0: A Shutter angle of 180 with a phase of -90 means that the shutter will be opened half a frame, centered around the current time