This filter is used for lightning shadows and midtones of an image without blowing the highlights. A detailed tutorial can be found at Appendice D, Mappatura tonale e recupero ombre usando le funzioni ‘Colori/Esposizione’ di GIMP.
«Presets» are a common feature for several Colors command. You can find its description in Sezione 8.1, «Introduzione al menu «Colori»».
This option is used to dispense with "useless" shadows and highlight information.
This option is used to add one or more stops of exposure compensation to the image.
These are common features described in Sezione 8.1, «Introduzione al menu «Colori»».