How do I apply a Photoshop filter to fixed parts of an image?

I have screenshots in multiple languages. Some (50) parts of the screenshot are private. I would like to use crystalize filter to pixelate those parts out. All screenshots have these private parts 🙂 in the same location, doing it only in one screenshot and copying that to all other would be ideal.

My idea is to create one ‘mask’ layer which has black rectangles over the areas with the private parts. But I fail to use the crystalize filter on all layers below only in places which have a black rectangle in the ‘mask’ layer.

Any idea if it is possible to apply a filter only in some places based on another layer?


  1. select the layer you want to edit in the layers palette;
  2. right alt+click the layer miniature of your mask layer–this creates a selection on your original layer, matching the places where your maske layer has pixels;
  3. apply your filter;
  4. select the next layer–the selection should still be intact;
  5. repeat as often as necessary.

Be sure to use the right alt key on your keyboard, the left one will do something different.

Source : Link , Question Author : ddofborg , Answer Author : Vincent

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