Light source device and endoscope system

A light source device that generates illumination light with which an object is irradiated, the light source device comprising:

• a plurality of semiconductor light emitting elements configured to emit light having different wavelength bands;
• and
• a controller configured to control a light emission profile of the plurality of semiconductor light emitting elements and drive the plurality of semiconductor light emitting elements,
• wherein the light emission profile defines (i-1) a pulse light emission period indicating a period in which the illumination light is emitted in at least a part of a pseudo global exposure period of an imaging element that images the subject or (i-2) a period in which the illumination light is emitted in at least a part of a pseudo global exposure period and a rolling shutter period of the imaging element, and (ii) a pulse light emission intensity indicating an intensity of the illumination light in the pulse light emission period,
• wherein in a case where an exposure level is increased, the controller extends the light emission profile in a first direction that is a direction opposite to a direction in which time progresses,
• wherein in a case where the exposure level is lowered, the controller shortens the pulse light emission period of the light emission profile from a second direction which is an advancing direction of time, and
• wherein in the case where the exposure level is lowered, when the light emission profile does not include light emission of the rolling shutter period in the second direction, while keeping a total light emission amount indicated by the light emission profile the same, the controller changes a light emission component in a rolling shutter period in the first direction with respect to the pseudo global exposure period to a light emission component in a rolling shutter period in the second direction with respect to the pseudo global exposure period, and after the controller changes the light emission profile by shifting to a light emission component in a certain rolling shutter period, the controller shortens a pulse light emission period of the light emission profile after the change from the second direction.