A high pressure lamp is driven with a pulse width modulated, alternating current pulses having an absolute value that is substantially constant and a short term average that varies approximately sinusoidally. , while the toner is obtained by dissolving or dispersing a toner composition in an organic solvent, further dispersing the solution or dispersion thereof in an aqueous medium containing fine resin particles as well as being reacted with a compound having an active hydrogen group, and removing the solvent from the obtained aqueous dispersion. The white pigment, which can be, for instance, calcium carbonate, has a median particle size of from about 0. Control signals for the scan sequence are calculated using the sequence control data, the global ambient condition parameter set, and the determined current sub-regions of the affected volumes, in order to optimize the functional sub-sequences at least with regard to the current sub-region of the assigned effective volume.