Though the color keying effects built into After Effects can be useful for some purposes, you should try keying with Keylight before attempting to use these built-in keying effects. Some keying effects have been superseded by more modern effects like Keylight.
For information about keying in general, including links to tutorials and other resources, see Keying introduction and resources.
The Color Difference Key effect creates transparency from opposite
starting points by dividing an image into two mattes, Matte Partial
A and Matte Partial B. Matte Partial B bases the transparency on
the specified key color, and Matte Partial A bases transparency
on areas of the image that don’t contain a second, different color.
By combining the two mattes into a third matte, called the alpha matte,
the Color Difference Key creates well-defined transparency values.
The Color Difference Key produces high-quality keying for all well-lit footage items shot against a bluescreen or greenscreen and works especially well with images that contain transparent or semitransparent areas, such as smoke, shadows, or glass.
This effect works with 8-bpc and 16-bpc color.
To use any of the eyedroppers in the Layer panel, choose Color Difference Key from the View menu in the Layer panel.
Thumbnail eyedropper: Select and then click in the Composition panel or the original thumbnail image on an appropriate area.
Key Color eyedropper: Select and then click in the Composition or Layer panel on an appropriate area.
Key Color swatch: Click to select a color from the specified color space.
The eyedropper tools move the sliders accordingly. Use the sliders in step 9 to fine-tune the keying results.
To produce the best possible key, make the black and white areas as different as you can so that the image retains as many shades of gray as possible.
Black sliders adjust the transparency levels of each matte. You can adjust the same levels using the Black eyedropper.
White sliders adjust the opaque levels of each matte. You can adjust the same levels using the White eyedropper.
Gamma sliders control how closely the transparency values follow a linear progression. At a value of 1 (the default), the progression is linear. Other values produce nonlinear progressions for particular adjustments or visual effects.
Choose Uncorrected to view a matte without adjustments.
Choose Corrected to view a matte with all adjustments.
To remove traces of reflected key color from the image, apply Spill Suppressor using Better For Color Accuracy. If the image still has a lot of color, apply the Simple Choker or Matte Choker effect.
Starting with the October 2013 release of After Effects CC, the Color Key effect has been moved to the Obsolete effects category. Use other effects such as the Keylight effect instead.
For information about keying in general, including links to tutorials and other resources, see Keying introduction and resources.
The Color Key effect keys out all image pixels that are similar to a specified key color. This effect modifies only the alpha channel of a layer.
This effect works with 8-bpc and 16-bpc color.
Click the Key Color swatch to open the Color dialog box and specify a color.
Click the eyedropper, and then click a color on the screen.
Though the color keying effects built into After Effects can be useful for some purposes, you should try keying with Keylight before attempting to use these built-in keying effects. Some keying effects have been superseded by more modern effects like Keylight.
For information about keying in general, including links to tutorials and other resources, see Keying introduction and resources.
The Color Range effect creates transparency by keying out a specified range of colors in either the Lab, YUV, or RGB color space. You can use this key on screens that consist of more than one color or on bluescreens or greenscreens that have been unevenly lit and contain different shades of the same color.
This effect works with 8-bpc color.
To use the eyedroppers in the Layer panel, choose Color Range from the View menu in the Layer panel.
The Difference Matte effect creates transparency by comparing a source layer with a difference layer, and then keying out pixels in the source layer that match both the position and color in the difference layer. Typically, it’s used to key out a static background behind a moving object, which is then placed on a different background. Often the difference layer is simply a frame of background footage (before the moving object has entered the scene). For this reason, the Difference Matte effect is best used for scenes that have been shot with a stationary camera and an unmoving background.
This effect works with 8-bpc and 16-bpc color.
A. Original image B. Background image C. New background image D. Final composite image
The imported image becomes the difference layer. Make sure that its duration is at least as long as the duration of the source layer.
If the shot doesn’t contain a full background frame, you may be able to assemble the full background by combining parts of several frames in After Effects or Photoshop. For example, you can use the Clone Stamp tool to take a sample of the background in one frame, and then paint the sample over part of the background in another frame.
Center
Places the difference layer in the center of the source layer. If the difference layer is smaller than the source layer, the rest of the layer fills with black.
Stretch To Fit
Stretches or shrinks the difference layer to the size of the source layer. Background images may become distorted.
The blurring occurs only for the comparison and doesn’t blur final output.
The Extract effect creates transparency by keying out a specified brightness range, based on a histogram of a specified channel. It’s best used to create transparency in an image shot against a black or white background or against a background that is dark or bright but consists of more than one color.
The controls for this effect are similar to the controls of the Extract effect in Adobe Premiere Pro, but the purpose and results of the effect are different.
This effect works with 8-bpc and 16-bpc color.
In the Effect Controls panel, the Extract effect displays a histogram for a channel specified in the Channel menu. The histogram displays a representation of the brightness levels in the layer, showing the relative number of pixels at each level. From left to right, the histogram extends from the darkest (a value of 0) to the lightest (a value of 255).
Using the transparency control bar beneath the histogram, you can adjust the range of pixels that are made transparent. The position and shape of the bar in relation to the histogram determine transparency. Pixels corresponding to the area covered by the bar remain opaque; pixels corresponding to the areas not covered by the bar are made transparent.
Drag the upper right or upper left selection handles to adjust the length of the bar and to shorten or lengthen the transparency range. You can also adjust the length by moving the White Point and Black Point sliders. Values above the white point and below the black point are made transparent.
Drag the lower right or lower left selection handles to taper the bar. Tapering the bar on the left affects the softness of transparency in the darker areas of the image; tapering it on the right affects the softness in the lighter areas. You can also adjust the softness levels by adjusting White Softness (lighter areas) and Black Softness (darker areas).
To taper the edges of the transparency control bar, first shorten the transparency bar.
Though the color keying effects built into After Effects can be useful for some purposes, you should try keying with Keylight before attempting to use these built-in keying effects. Some keying effects have been superseded by more modern effects like Keylight.
For information about keying in general, including links to tutorials and other resources, see Keying introduction and resources.
The Inner/Outer Key effect isolates a foreground object from its background.
This effect works with 8-bpc and 16-bpc color.
To use the Inner/Outer key, create a mask to define the inside and outside edge of the object you want to isolate. The mask can be fairly rough—it doesn’t need to fit exactly around the edges of the object.
In addition to masking a soft-edged object from its background, Inner/Outer Key modifies the colors around the border to remove contaminating background colors. This color decontamination process determines the contribution of the background to the color in each border pixel, and then removes that contribution—thus removing the halo that can appear if a soft-edged object is matted against a new background.
Draw a single closed mask near the border of the object; then select the mask from the Foreground menu and leave the Background menu set to None. Adjust the Single Mask Highlight Radius to control the size of the border around this mask. (This method works well only on objects with simple edges.)
Draw two closed masks: an inner mask just inside the object, and an outer mask just outside the object. Make sure that any fuzzy or uncertain areas of the object lie within these two masks. Select the inner mask from the Foreground menu and the outer mask from the Background menu.
Make sure that the mask mode for all masks is set to None.
You can select the Background (outer) mask as a Cleanup Background mask to clean up noise from the background portions of the image.
Though the color keying effects built into After Effects can be useful for some purposes, you should try keying with Keylight before attempting to use these built-in keying effects. Some keying effects have been superseded by more modern effects like Keylight.
For information about keying in general, including links to tutorials and other resources, see Keying introduction and resources.
Linear keys create a range of transparency across an image. A linear key compares each pixel in the image to the key color you specify. If the color of a pixel closely matches the key color, it becomes completely transparent. Pixels that don’t match as well are made less transparent, and pixels that don’t match at all remain opaque. The range of transparency values, therefore, forms a linear progression.
The Linear Color Key effect uses RGB, hue, or chroma information to create transparency from a specified key color.
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
In the Effect Controls panel, the Linear Color Key effect displays two thumbnail images; the left thumbnail image represents the unaltered source image, and the right thumbnail image represents the view you’ve selected in the View menu.
You can adjust the key color, the matching tolerance, and the matching softness. The matching tolerance specifies how closely pixels must match the key color before they start becoming transparent. The matching softness controls the softness of edges between the image and the key color.
You can also reapply this key to preserve a color that was made transparent by the first application of the key. For example, if you key out a medium-blue screen, you may lose some or all of a light-blue piece of clothing your subject is wearing. You can bring back the light-blue color by applying another instance of the Linear Color Key and choosing Keep This Color from the Key Operation menu.
Source Only
Shows the original image without the key applied.
Matte Only
Shows the alpha channel matte. Use this view to check for holes in the transparency. To fill undesired holes after you complete the keying process, see Close a hole in a matte.
Select the Thumbnail eyedropper, and then click an appropriate area in the Composition panel or the original thumbnail image.
Select the Key Color eyedropper, and then click an appropriate area in the Composition or Layer panel.
To preview transparency for different colors, select the Key Color eyedropper, hold down the Alt key (Windows) or Option key (Mac OS), and move the pointer to different areas in the Composition panel or the original thumbnail image. The transparency of the image in the Composition panel changes as you move the pointer over different colors or shades. Click to select the color.
Click the Key Color swatch to select a color from the specified color space. The selected color becomes transparent.
note: The eyedropper tools move the sliders accordingly. Use the sliders in steps 6 and 7 to fine-tune the keying results. To use eyedroppers in the Layer panel, choose Linear Color Key from the View menu in the Layer panel.
Select the Plus (+) or the Minus (-) eyedropper, and then click a color in the left thumbnail image. The Plus eyedropper adds the specified color to the key color range, increasing the matching tolerance and the level of transparency. The Minus eyedropper subtracts the specified color from the key color range, decreasing the matching tolerance and the level of transparency.
Drag the matching tolerance slider. A value of 0 makes the entire image opaque; a value of 100 makes the entire image transparent.
Starting with the October 2013 release of After Effects CC, the Luma Key effect has been moved to the Obsolete effects category and users are recommended to use other effects such as the Keylight effect.
For information about keying in general, including links to tutorials and other resources, see Keying introduction and resources.
The Luma Key effect keys out all the regions of a layer with a specified luminance or brightness. The quality setting of the layer doesn’t influence the Luma Key effect.
Use this effect if the object from which you want to create a matte has a greatly different luminance value than its background. For example, if you want to create a matte for musical notes on a white background, you can key out the brighter values; the dark musical notes become the only opaque areas.
This effect works with 8-bpc and 16-bpc color.
Starting with the June 2014 release of After Effects CC, the Spill Suppressor effect has been moved to the Obsolete effects category and users are recommended to use the Advanced Spill Suppressor effect.
The Key Cleaner effect recovers alpha-channel detail from a scene keyed by a typical keying effect, including recovering detail lost due to compression artifacts.
If you see that unwanted semi-transparency effects have crept in along edges that should be sharp, use an effect mask (with a little mask feather) to restrict the Key Cleaner effect to the intended area.
The Advanced Spill Suppressor effect removes color spill on a foreground subject from a colored background used for color keying.
The Advanced Spill Suppressor effect has two methods for spill suppression:
An easy way of applying these effects is by using the Keylight + Key Cleaner + Spill Suppressor animation preset.
Starting with the June 2014 release of After Effects CC, the Spill Suppressor effect has been moved to the Obsolete effects category and users are recommended to use the Advanced Spill Suppressor effect.
After Effects includes several built-in keying effects, as well as the Academy Award–winning Keylight effect, which excels at professional-quality color keying. For information on the Keylight effect, see its documentation in the folder in which the Keylight plug-in is installed. (See Plug-ins.)
For information about keying in general, including links to tutorials and other resources, see Keying introduction and resources.
The Key Color property is already linked with an expression to the Keylight effect's Screen Colour property, so you don't need to change it unless you want to use a different color for the despill process. To use a different color for the despill process, just disable or remove the Keylight expression.
Follow the steps below to apply the Keylight effect with the Key Cleaner and Advanced Spill Suppressor effect:
If you see unwanted semitransparency along edges that should be sharp, use an effect mask (with a little bit of mask feather) to restrict Key Cleaner to the intended area.
See variable-width mask feathering and soften the edges of a mask articles for information on mask feathering
Follow the steps below to apply the Key Cleaner and Advanced Spill Suppressor effect to a keying effect other than the Keylight effect:
Watch this video to learn how to get better keying results from compressed or badly shot green-screen footage with the new Key Cleaner effect and remove color spill with the Advanced Spill Suppressor controls.
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