Imaging system and endoscope system

An imaging system comprising:

• an illumination portion configured to emit illumination light with which a main target is illuminated;
• an imager including pixels two-dimensionally arrayed and each configured to generate an electrical signal by photoelectrically converting received light;
• a reader having a reading period during which part of lines of the pixels are read in one of one frame period and one field period and configured to sequentially read the electrical signals generated by the pixels for each line of the pixels;
• and
• an illumination controller configured to control an intensity of the illumination light based on modulated illumination for modulating the intensity of the illumination light in a non-reading period as a period other than the reading period,
• wherein in the non-reading period, the modulated illumination has a first integrated light amount as a product of a variable intensity of a first pulse and an output period of the illumination light and a second integrated light amount as a product of a constant intensity of a second pulse and the output period,
• wherein in the non-reading period, the illumination controller causes a predetermined light amount that is not larger than a maximum value of the first integrated light amount and is not smaller than a minimum value of the second integrated light amount to transit between the first integrated light amount and the second integrated light amount,
• wherein as the illumination controller increases a light amount of the illumination light in one of the one frame period and the one field period in a state in which the first integrated light amount is a maximum integrated light amount, the illumination controller performs a first increasing transition operation of decreasing the first integrated light amount by a predetermined transition amount and increasing the second integrated light amount by the predetermined transition amount, and
• wherein the illumination controller adjusts the output period of the first pulse after the first increasing transition operation so that an increased amount of the light amount of the illumination light corresponds to the first integrated light amount.