maskUse

Last update: August 22, 2023

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Image mask usage. Specifies how the mask or alpha channel of the image is used for operations on the image (for example, colorize=). When specified in an effect layer, it allows applying the effect to the background area of parent layer or to the entire parent layer rectangle.

maskUse=norm|invert|off

The following table illustrates the effect of maskUse= depending on availability and type of the mask (alpha channel) associated with the layer image.

ValueNo maskUnassociated alpha (or separate mask image)Associated (pre-multiplied) alpha
offOpaque image rectangleOpaque image rectangleForeground area of image over rectangle filled with solid black
normOpaque image rectangleForeground area of imageForeground area of image or layer
invertHidden layerBackground area of imageBackground area of image or layer filled with solid black

Properties

Image or layer attribute. Applies to layer 0 if layer=comp. If specified in an effect layer, the command modifies the mask inherited from the parent layer.

The behavior of maskUse= is undefined and unsupported when specified with text or solid color layers when no image mask is applicable (specified with mask= or catalog::Mask).

Default

maskUse=norm

Example

Colorize the background area of an image; the image foreground is defined by a separate mask image. This is achieved by layering the colorized image background on top if the unmodified image:

http://server/myRootId/myImageId?layer=1&src=myImageId&mask=myImgMask&maskUse=invert&colorize=0x306090

See also

color= , mask=

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