Blur image. Applies a blur filter to the image data.
Blur filter radius in pixels (real 0..100).
radius is in pixels relative to the composite image. Also used to feather layer effects.
Layer command. Applies to the current layer or to the composite image if layer=comp.
op_blur=0, for no blur effect.
Blur the background of an image. A separate mask image is referenced by catalog::MaskPath. Note that layer=0 must be specified explicitly, otherwise op_blur would be applied to the entire composite image.