A method for contrast-based autofocus of an image capture device. The method includes obtaining sensor data representative of an image captured by the image capture device, wherein the sensor data comprises pixel values from respective sensor pixels of an image sensor of the image capture device. A subset of the pixel values is dynamically selected to generate selected sensor data representative of the subset of the pixel values. The selected sensor data is processed to generate contrast data representative of a contrast-based characteristic of at least a portion of the image. The contrast data is processed to determine a focus setting for the image capture device.