Typical values would be 0.1-0.2. A value of 0 means use the exposure time as the background time. Use a previously computed background in the specified file in place of constructing new per-scale normalized backgrounds. The scale sizes themselves for a particular run do not have to be equal, though initial usage of asymmetric wavelets is not advised. Wtransform produces a complete set of outputs for each scale.
Small scales tend to detect small features, and larger scales larger features.
The number of scale sizes indicated by yscales must be the same as xscales. See additional notes under 'xscales'. Maximum number of cleansing iterations per scale pair. 4 is usually adequate. The user specifies how many iterations the program should go through to calculate the background.