Tunable bandpass filters are provided. The input image is automatically analyzed to determine an edge map image indicating light-side edge regions that include edge pixels that are adjacent to edge transitions in the input image and are on a lighter side of the edge transition. The leading body is supported by the travel body main unit so as to be pivotable in a horizontal plane. The method comprises utilizing as the foam controlling agent an alkyl glycidyl ether-capped diamine compound of the formula: . The etch solutions are used with a wide variety of substrates, for example, in the etching of silicon oxide-containing substrates. The filler material may be a non-compressible filler material.