The Compound Blur effect blurs pixels in the effect layer based on the luminance values of a control layer, also known as a blur layer or blurring map. By default, bright values in the blur layer correspond to more blurring of the effect layer, while dark values correspond to less blurring; select Invert Blur for light values to correspond to less blurring.

This effect is useful for simulating smudges and fingerprints, or changes in visibility caused by atmospheric conditions such as smoke or heat, especially with animated blur layers such as those generated with the Fractal Noise effect.

This effect works with 8-bpc, 16-bpc, and 32-bpc color.

Original (top left), blur layer (bottom left), and result (bottom right)

Maximum Blur

The maximum amount, in pixels, that any part of the affected layer can be blurred.

Stretch Map To Fit

Stretches the control layer to the dimensions of the layer to which it is applied; otherwise, the control layer is centered on the effect layer.