I recall a thread last year that pertained to locking transparent pixels in a layer so as not to 'pull' them in to a blur filter on an adjacent layer when creating depth of field. Have searched the forum but am unable to locate the thread. Does any one recall this technique and or retained a copy of the original thread?
Also, can a similar method by applied to layers containing masks? For example, in a simple situation where you have two masked layers: #1 Foreground subject layer with background masked combined with a #2 back ground layer with foreground masked and you wish to gradient blur the BG without it 'pulling' in and blurring edge pixels from the foreground, can the masked pixels of the FG on the BG layer be locked???