chTypeGray_3.setChannelName("1");
chTypeGray_3.setContrastEnhancement(cntEnh_3);
chSel_3.setGrayChannel(chTypeGray_3);
rsb_3.setChannelSelection(chSel_3);
rsb_3.setOpacity(sldBuilder.literalExpression(1.0));
rsb_3.setOverlap(sldBuilder.literalExpression("AVERAGE"));
// visit the RasterSymbolizer
rsh_StyleBuilder.visit(rsb_3);
testRasterSymbolizerHelper(rsh_StyleBuilder);