Patent Document ID: 20090278964
Application ID: 12434116
Patent Status: 0

Claim One:
1. A method for capturing a long exposure with a digital camera by dividing the long exposure into a plurality of shorter exposures, wherein the digital camera includes an image sensor that (a) is assigned an inherent ISO speed rating that determines at least in part an overall photographic exposure upon the image sensor, and (b) generates an image signal for each shorter exposure and a dark current comprising both a fixed pattern offset component and a random noise component, said method comprising the steps of: increasing the overall photographic exposure upon the image sensor; capturing the shorter exposures as a plurality of image frames; generating an image representation of the long exposure from the plurality of image frames; generating a representation of the dark current in the plurality of image frames; processing the image representation and the representation of the dark current in order to remove the fixed pattern offset component of the dark current from the image representation, thereby generating a processed image representation; and scaling the processed image representation proportional to the increased overall photographic exposure whereby the scaling additionally reduces the random noise component in the image representation; wherein the step of increasing the overall photographic exposure upon the image sensor comprises reducing the ISO speed rating for the shorter exposures below the inherent ISO speed rating such that the image signal for each shorter exposure accumulates to a greater extent than it would, had the inherent ISO speed rating been used; and wherein the step of scaling the image representation comprises scaling the image representation proportional to the reduced ISO speed rating whereby the scaling additionally reduces the random noise component in the image representation.