1. A computer-implemented method, comprising: obtaining, at a first time, first image data using a first set of pixels located substantially at a first edge of a gesture sensor of a computing device; obtaining, at the first time, second image data using a second set of pixels located substantially at a second edge of the gesture sensor, the second edge opposing the first edge; determining a first ratio of first pixels in the first image data and second pixels in the second image data; capturing, at a second time, third image data using the first set of pixels; capturing, at the second time, fourth image data using the second set of pixels; determining a second ratio of third pixels in the third image data and fourth pixels in the fourth image data; and detecting a gesture based on a difference between the first ratio and the second ratio exceeding a threshold.