Displacement Map effect
置换贴图效果
The Displacement Map effect distorts a layer by displacing pixels horizontally and vertically based on the color values of pixels in the control layer specified by the Displacement Map Layer property. The type of distortion created by the Displacement Map effect can vary greatly, depending on the control layer and options you select.
置换贴图效果通过置换水平与垂直方向的像素来达到扭曲图层的效果，原理是根据置换贴图属性来指定图层中像素的色值。根据所选择的图层与选项不同，扭曲的类型也会变化很大。
The displacement is determined from the color values of the displacement map. The color values range from 0 to 255. Each value is converted into a scale ranging from -1 to 1. The displacement amount is calculated by multiplying the converted value by the maximum displacement amount you specify. A color value of 0 produces maximum negative displacement (–1 * maximum displacement). A color value of 255 produces maximum positive displacement. A color value of 128 produces no displacement.
置换效果取决于置换图层的色值，色值范围从0-255。每一个值转换为一个从-1到1的缩放范围。置换数量通过转换值乘以指定的最大置换数量得出。0表示最大数量的负置换（-1*最大置换值）255表示最大数量的正置换。128表示没有置换。
The effect uses the control layer specified by Displacement Map Layer, without considering any effects or masks. If you want to use the control layer with its effects, precompose it. If the control layer isn’t the same size as the layer to which the effect is applied, it is centered, stretched, or tiled depending on the setting for Displacement Map Behavior.
置换贴图中的置换层不包含任何效果与遮罩。如果希望使用置换层中的效果，预合成次图层。如果置换层与应用置换贴图效果层的尺寸不同，可修改置换贴图属性来设置：居中、拉伸、平铺。
Select Expand Output to allow the results of the effect to extend beyond the original boundaries of the layer to which it’s applied. Select? Pixels Around to copy pixels displaced outside the original layer boundaries to the opposite side of the layer; that is, pixels pushed off the right side appear on the left side, and so on.
选择扩展输出可在应用了效果的图层上实现超过原始素材边界的效果。选择扭曲像素包围表示将在原始图层边界外部的像素复制到图层的另一侧，将右侧的像素推出到左侧。
