METHODS FOR CAPTURING AND READING OUT IMAGES FROM AN IMAGE SENSOR
Multiple images are captured where the exposure times for some of the images overlap and the images are spatially overlapped. Charge packets are transferred from one or more portions of pixels after particular integration periods, thereby enabling the portion or portions of pixels to begin another integration period while one or more other portions of pixels continue to integrate charge. Charge packets may be binned during readout of the images from the image sensor. Comparison of two or more images having different lengths of overlapping or non-overlapping exposure periods provides motion information. The multiple images can then be aligned to compensate for motion between the images and assembled into a combined image with an improved signal to noise ratio and reduced motion blur.
1 . A method for capturing spatially overlapped images having different integration periods using an image sensor comprising a plurality of pixels each including a photosensitive area and a plurality of vertical charge-coupled devices (VCCDs), the method comprising:
beginning light integration for all of the pixels;
after a first period of time, resetting a first portion of pixels by transferring charge packets from photosensitive areas in the first portion of pixels to the VCCDs;
after a second period of time, ending light integration for all of the pixels;
transferring charge packets from photosensitive areas in a second portion of pixels to the VCCDs wherein the second portion of pixels is different from the first portion of pixels;
reading out the charge packets in the VCCDs;
transferring charge packets from the first portion of pixels into the VCCDs; and
reading out the charge packets in the VCCDs.
2 . The method of claim 1 , wherein beginning light integration for all of the pixels comprises opening a mechanical shutter.
3 . The method of claim 2 , wherein ending light integration for all of the pixels comprises closing the mechanical shutter.
4 . The method of claim 1 , wherein the first portion of pixels capture two images and the second portion of pixels capture one image.
5 . The method of claim 4 , wherein an exposure period for the image captured by the second portion of pixels at least partially overlaps an exposure period for at least one of the images captured by the first portion of pixels, and the exposure periods for the two images captured by the first portion of pixels do not overlap.
6 . The method of claim 4 , further comprising determining motion by comparing the two images captured by the first portion of pixels.
7 . The method of claim 4 , further comprising combining the three images to produce a reduced blur and reduced noise image.
8 . The method of claim 1 , wherein the first and second portions each comprise a single line of pixels.
9 . The method of claim 1 , wherein the first and second portions of pixels each comprise multiple lines of pixels.
10 . The method of claim 9 , wherein the multiple lines of pixels comprises multiple adjacent lines of pixels, and wherein the first portion of pixels alternates with respect to the second portion of pixels.
11 . The method of claim 1 , wherein transferring charge packets from photosensitive areas in a first portion of pixels to the VCCDs comprises transferring charge packets from odd numbered rows of pixels to the VCCDs.
12 . The method of claim 11 , wherein transferring charge packets from photosensitive areas in a second portion of pixels to the VCCDs comprises transferring charge packets from even numbered rows of pixels to the VCCDs.
13 . The method of claim 12 , further comprising binning at least a portion of the charge packets in the VCCDs when transferring charge packets from the second portion of pixels to the VCCDs.
14 . The method of claim 13 , wherein binning at least a portion of the charge packets in the VCCDs when transferring charge packets from the second portion of pixels to the VCCDs comprises binning charge packets of the same color in the VCCDs by transferring charge packets from the second portion of pixels to the VCCDs.
15 . The method of claim 13 , wherein binning at least a portion of the charge packets in the VCCDs when transferring charge packets from the second portion of pixels to the VCCDs comprises binning charge packets of different colors in the VCCDs by transferring charge packets from the second portion of pixels to respective charge storage elements in the VCCDs.
16 . The method of claim 1 , further comprising binning at least a portion of the charge packets in the VCCDs by shifting charge packets within the VCCDs.
17 . The method of claim 16 , wherein binning at least a portion of the charge packets in the VCCDs by shifting charge packets within the VCCDs comprises binning charge packets of different colors in the VCCDs by shifting charge packets one or more charge storage elements in the VCCDs.
18 . The method of claim 16 , wherein binning at least a portion of the charge packets in the VCCDs by shifting charge packets within the VCCDs comprises binning charge packets of the same color in the VCCDs by shifting charge packets within the VCCDs.