# NodeBox

Create visual output with Python programming code
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# photobot.Layer.mask()

## Syntax

    canvas.layers[i].mask()

## Description

Masks the layer below with layer i. This means that the current layer is blended with the alpha channel of the layer below. Primarily, masking is useful when using gradient layers as alpha channel on images below, to make them transparent on the edges for example.

## Example

    photobot = ximport("photobot")
    canvas = photobot.canvas(100,100)
    canvas.layer("robot.jpg")
    canvas.layer("robot.jpg")
    canvas.layers[2].flip()
    canvas.gradient(photobot.LINEAR)
    canvas.layers[3].mask()