A device for use in endoscopy, the device comprising an offset subtraction unit; an image sensor which is configured to receive, for each of a plurality of bright frames, a respective image signal obtained by optical imaging of at least part of a field of view of an imaging device during a respective exposure time of the image sensor, and to transmit the same to the offset subtraction unit at a first frame rate, and which is configured to receive, for at least one dark frame, a respective image signal obtained by the optical imaging of the at least part of the field of view of the imaging device during a respective exposure time of the image sensor, and to transmit the same to the offset subtraction unit at a second frame rate; a control unit which is configured to ensure that the image sensor alternately transmits a number of bright frames and at least one dark frame to the offset subtraction unit, wherein the control unit is configured to ensure that, on the assumption that a scene in the at least part of the field of view of the imaging device is equal in the exposure time for the at least one dark frame and in the respective exposure time of each of the bright frames, a respective amount of light which is detected by the image sensor in the respective exposure time and by which the respective image signal for each of the bright frames is generated, is larger than a respective amount of light which is detected by the image sensor in the respective exposure time and by which the respective image signal for the at least one dark frame is generated; the offset subtraction unit is configured to obtain an offset based on the image signal of the at least one dark frame, to subtract the offset from a signal based on an image signal of one of the bright frames so as to obtain a calibrated signal, and to provide the calibrated signal for further processing, wherein the at least one dark frame and the number of bright frames constitute a sequence of frames directly following each other in time. an offset subtraction unit; an image sensor which is configured to receive, for each of a plurality of bright frames, a respective image signal obtained by optical imaging of at least part of a field of view of an imaging device during a respective exposure time of the image sensor, and to transmit the same to the offset subtraction unit at a first frame rate, and which is configured to receive, for at least one dark frame, a respective image signal obtained by the optical imaging of the at least part of the field of view of the imaging device during a respective exposure time of the image sensor, and to transmit the same to the offset subtraction unit at a second frame rate; a control unit which is configured to ensure that the image sensor alternately transmits a number of bright frames and at least one dark frame to the offset subtraction unit, wherein the control unit is configured to ensure that, on the assumption that a scene in the at least part of the field of view of the imaging device is equal in the exposure time for the at least one dark frame and in the respective exposure time of each of the bright frames, a respective amount of light which is detected by the image sensor in the respective exposure time and by which the respective image signal for each of the bright frames is generated, is larger than a respective amount of light which is detected by the image sensor in the respective exposure time and by which the respective image signal for the at least one dark frame is generated; the offset subtraction unit is configured to obtain an offset based on the image signal of the at least one dark frame, to subtract the offset from a signal based on an image signal of one of the bright frames so as to obtain a calibrated signal, and to provide the calibrated signal for further processing, wherein the at least one dark frame and the number of bright frames constitute a sequence of frames directly following each other in time.