A camera comprising: a shutter mechanism; an image sensor comprising sensing elements; means to include a lens mechanism for conducting light from an image scene through an aperture mechanism and said shutter mechanism to the image sensor; an image processor for controlling the aperture mechanism and the shutter mechanism via a set of control signals; wherein the image sensor accumulates electrical charge in its sensing elements during exposure periods, and accumulates charge in its sensing elements during exposure periods as a result of dark currents in the image sensor; and the image processor is arranged to generate signals via the control signals (24, 26) to start exposure periods, stop exposure periods and to read out samples from the image sensor; further comprising an analog-to-digital (A/D) converter, wherein the A/D converter is arranged to digitize the samples and to provide corresponding digitized samples to the image processor; wherein: the camera comprises means for obtaining a dark frame from the image sensor, said means comprising: - means for obtaining a dark sample from each of a set of active elements of the image sensor; - means for obtaining a dark sample from each of a set of optically black elements (30,34) of the image sensor; and the camera comprising means for obtaining an image frame from the image sensor said means comprising: - means for obtaining an image sample from each active element; - means for obtaining an image sample from each optically black element; wherein the image processor is arranged to effect dark current subtraction by scaling the dark frame in response to changes in dark current levels in the image sensor, characterized in that: the means for obtaining a dark frame from the image sensor comprise: - means for obtaining a set of dummy samples that represent a low charge level in the image sensor; and the means for obtaining an image frame from the image sensor comprise: - means for obtaining a set of dummy samples from the image sensor. a shutter mechanism; an image sensor comprising sensing elements; means to include a lens mechanism for conducting light from an image scene through an aperture mechanism and said shutter mechanism to the image sensor; an image processor for controlling the aperture mechanism and the shutter mechanism via a set of control signals; wherein the image sensor accumulates electrical charge in its sensing elements during exposure periods, and accumulates charge in its sensing elements during exposure periods as a result of dark currents in the image sensor; and the image processor is arranged to generate signals via the control signals (24, 26) to start exposure periods, stop exposure periods and to read out samples from the image sensor; further comprising an analog-to-digital (A/D) converter, wherein the A/D converter is arranged to digitize the samples and to provide corresponding digitized samples to the image processor; wherein: the camera comprises means for obtaining a dark frame from the image sensor, said means comprising: - means for obtaining a dark sample from each of a set of active elements of the image sensor; - means for obtaining a dark sample from each of a set of optically black elements (30,34) of the image sensor; and - means for obtaining a dark sample from each of a set of active elements of the image sensor; - means for obtaining a dark sample from each of a set of optically black elements (30,34) of the image sensor; and the camera comprising means for obtaining an image frame from the image sensor said means comprising: - means for obtaining an image sample from each active element; - means for obtaining an image sample from each optically black element; wherein - means for obtaining an image sample from each active element; - means for obtaining an image sample from each optically black element; the image processor is arranged to effect dark current subtraction by scaling the dark frame in response to changes in dark current levels in the image sensor, characterized in that: the means for obtaining a dark frame from the image sensor comprise: - means for obtaining a set of dummy samples that represent a low charge level in the image sensor; and the means for obtaining an image frame from the image sensor comprise: - means for obtaining a set of dummy samples from the image sensor. the means for obtaining a dark frame from the image sensor comprise: - means for obtaining a set of dummy samples that represent a low charge level in the image sensor; and - means for obtaining a set of dummy samples that represent a low charge level in the image sensor; and the means for obtaining an image frame from the image sensor comprise: - means for obtaining a set of dummy samples from the image sensor. - means for obtaining a set of dummy samples from the image sensor.