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System object: vision.AlphaBlender
Package: vision

Blend images, overlay images, or highlight selected pixels


Y = step(H,I1,I2)
Y = step(H,I1,I2,OPACITY)
Y = step(H,I1,I2,MASK)
Y = step(H,I1,MASK)
Y = step(H,I1,I2,...,LOCATION)



Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.

Y = step(H,I1,I2) performs the alpha blending operation on images I1 and I2.

Y = step(H,I1,I2,OPACITY) uses OPACITY input to combine pixel values of I1 and I2 when you set the Operation property to Blend and the OpacitySource property to Input port.

Y = step(H,I1,I2,MASK) uses MASK input to overlay I2 over I1 when you set the Operation property to Binary mask and the MaskSource property to Input port'.

Y = step(H,I1,MASK) uses MASK input to determine which pixels in I1 are set to the maximum value supported by their data type when you set the Operation property to Highlight selected pixels and the MaskSource property to Input port.

Y = step(H,I1,I2,...,LOCATION) uses LOCATION input to specify the upper-left corner position of I2 when you set the LocationSource property to Input port.


H specifies the System object on which to run this step method.

The object performs an initialization the first time the step method is executed. This initialization locks nontunable properties and input specifications, such as dimensions, complexity, and data type of the input data. If you change a nontunable property or an input specification, the System object issues an error. To change nontunable properties or inputs, you must first call the release method to unlock the object.