Apple applies for US2012/041398 patent titled "Image Sensor Having HDR Capture Capability" by Michael Frank.
"...there exist disadvantages to the process of generating a HDR image from multiple independently captured images. For example, changes may occur when images are captured successively such that a composite HDR image generated therefrom may not be completely aligned. This may generate motion artifacts in the composite HDR image. Further, the images may be affected by local motion in the image scene, e.g., trees swaying in the wind, people and faces shifting slightly, etc. Additionally, the time required for a HDR image to be processed may be delayed based on the images to be captured."