by Julieanne Kost
To apply multiple filters to a single layer – each with its own filter mask – convert the layer into a smart object (Layer > Smart Objects > Convert to Smart Objects). Apply the first smart filter and paint in the mask as desired. To apply the second filter, choose Layer > Smart Objects > Convert to Smart Object (essentially “nesting” one smart filter within another), apply the second filter and paint in the mask as desired. If you need to edit the settings or mask for the first filter, choose Layer > Smart Object > Edit Contents. This technique is also an excellent way to selectively sharpen and blur an image.
In the illustration above, the High Pass filter was applied to the Smart Object (Layer 0) and then masked so that it is limited to sharpening the cactus. Note: If you use the High Pass filter to sharpen an image, you can double-click the small icon to the right of the filter name in the Layers panel and set the blend mode to Overlay or Soft Light to remove the grayish look of the filter.)
After applying the first smart filter, choosing Layer > Smart Objects > Convert to Smart Object nests the first smart filter and allows the addition of another filter (in this example Oil Paint) with its own Smart Filter mask.