The invention is based on a method for controlling a
flashlight in connection with a
digital image sensor without a mechanical
shutter, wherein the
exposure of the
image sensor is performed in sub-areas, such as pixel rows or columns, or in another order, by using a rolling
electronic shutter or the like. Thus, the
exposure of said sub-areas of the
image sensor takes place at least partly at different times. According to the invention, during the time of
exposure of one image, i.e. substantially all the sub-areas of the
image sensor, several discrete, successive flashes of the
flashlight are used to achieve even exposure of the
image area, which the flashes are timed in such a way that each
single flash is triggered at a point of time which is common to the integration or exposure time of as many successive sub-areas of the image sensor as possible. According to the invention, the successive
light flashes are also timed in such a way that one and only one flash of the
flashlight occurs during the integration or exposure time of each single sub-area. By the present invention, the significant
advantage is attained that the invention minimizes the number of
light flashes required for one image while it also secures that each sub-area of the sensor to be exposed at a different time is illuminated as evenly as possible.