Explain why the "custom filter" in Adobe Photoshop (Fig. 5.6) is not strictly a linear filter Fig. 5.6 Adobe Photoshop's "Custom Filter" implements linear fil- ters up to a size of 5 5 The filter's coordinate ori- gin ("hot spot") is assumed to be at the center (value set to 3 in this example), and empty cells correspond to zero co- efficicnts. In addition to tho (integer) coefficients, common Scale and Offset values can be spccificd (scc Eqn. (5.11)) Custom Reset Load 100% Preview Scale: 15 Offset