The step the slider sets.
OptionalparamThe parameter; default the step's main value (opInfo[op].value). Required for levels.
OptionallabelText before the slider. Default: the label for op or op.param in labels.
OptionalminLeft end of the slider.
OptionalmaxRight end of the slider.
OptionalstepSlider step.
OptionalvalueThe neutral value, set by reset. Default: the parameter's default in opInfo (0 for the sharpen amount).
One slider of an EnhanceControl. Ranges not given come from
opInfo.