Motion clutter suppression for image-subtracting cameras
First Claim
1. An apparatus for generating eye images including an image-generation apparatus comprising:
- an image sensor that generates an output from a physical wave input;
two constituent-image accumulators;
an accumulator-control switch that directs the image-sensor output to either one of the two constituent-image accumulators;
a controller for the accumulator-control switch that toggles the image sensor output between the two constituent-image accumulators over multiple sub-periods within an overall frame-capture period, wherein the sub-periods of the constituent images are temporally interleaved; and
a processor that subtracts the constituent images from the two constituent-image accumulators to form a composite image.
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Accused Products
Abstract
Embodiments of the present invention relate to systems and methods for minimizing motion clutter in image-generation devices. Temporally-interleaved image-subtraction reduces the magnitude of motion clutter and has no adverse effect on the desired ambient-light cancellation of static images. Embodiments of image-generation devices employing temporally-interleaved image-subtraction include single, double, triple, and series accumulator configurations. All four embodiments allow synchronization with scene illuminators and may be implemented on a single electronic chip. Temporally-interleaved image-subtraction is particularly well suited for use in video eyetracking applications where ambient light and scene motion can cause significant problems.
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Citations
34 Claims
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1. An apparatus for generating eye images including an image-generation apparatus comprising:
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an image sensor that generates an output from a physical wave input;
two constituent-image accumulators;an accumulator-control switch that directs the image-sensor output to either one of the two constituent-image accumulators; a controller for the accumulator-control switch that toggles the image sensor output between the two constituent-image accumulators over multiple sub-periods within an overall frame-capture period, wherein the sub-periods of the constituent images are temporally interleaved; and a processor that subtracts the constituent images from the two constituent-image accumulators to form a composite image. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for generating eve images including an image-generation apparatus comprising:
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an image sensor that generates an output from a physical wave input; a sub-period accumulator that accumulates the image-sensor output within individual sub-frame periods; two constituent-image accumulators that accumulate constituent images comprised of different sets of sub-images from the sub-period accumulator; an accumulator-control switch that directs the output from the sub-period accumulator to be added to either one of the constituent-image accumulators; a controller, wherein the controller initializes the sub-period accumulator before each sub-period and generates an accumulator-control switch signal that toggles the output of the sub-period accumulator between the two constituent-image accumulators over multiple sub-periods within an overall frame-capture period, wherein the sub-periods of the constituent images are temporally interleaved; and a processor that subtracts the constituent images from the two constituent-image accumulators to form a composite image. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An apparatus for generating eye images including an image-generation apparatus comprising;
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an image sensor that generates an output from a physical wave input; an image accumulator that forms a composite image; an accumulator-control switch that controls whether the image-sensor output is added to or subtracted from the image accumulator; and a controller for the accumulator-control switch that toggles between addition and subtraction over multiple sub-periods within an overall frame-capture period, wherein the sub-periods of the constituent images are temporally interleaved. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. An apparatus for generating eye images including an image-generation apparatus comprising:
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an image sensor that generates an output from a physical wave input; a sub-period accumulator that accumulates the image-sensor output within individual sub-frame periods; a composite-image accumulator that accumulates a composite image comprised of added and subtracted sets of sub-images; an accumulator-control switch that directs the output from the sub-period accumulator to be added to or subtracted from the composite-image accumulator; and a controller that initializes the sub-period accumulator before each sub-period and generates an accumulator-control switch signal that toggles between addition and subtraction over multiple sub-periods within an overall frame-capture period, wherein the sub-periods of the constituent images are temporally interleaved. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A method for generating eye images including a method for suppressing motion clutter comprising:
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accumulating a first image during a first sub-period; accumulating a second image during a second sub-period; accumulating a third image during a third sub-period; accumulating a fourth image during a fourth sub-period; adding the first image to the third image to derive the first sub-composite image; adding the second image to the fourth image to derive the second sub-composite image; and subtracting the second sub-composite image from the first sub-composite image to form a composite image, wherein the second sub-period is between the first and third sub-periods, and the third sub-period is between the second and fourth sub-periods. - View Dependent Claims (30, 31)
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32. A method for generating eye images including a method for suppressing motion clutter comprising:
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capturing a first image during a first sub-period; capturing a second image during a second sub-period; calculating a first sub-composite image from the difference between the first image and second image; capturing a third image during a third sub-period; calculating a second sub-composite image from the difference between the third image and the first sub-composite image; capturing a fourth image during a fourth sub-period; and calculating a composite image from the difference between the fourth image and the second sub-composite image. - View Dependent Claims (33, 34)
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Specification