Apple has applied for a patent to improve image capture quality on mobile devices by automatically buffering many still images while the user previews the shot, and then automatically selecting the best image or combination of images once the user presses the camera’s shutter button. The described process aims to address issues like movement delays and camera shake, producing better final shots that are more representative of the scene that a user intended to capture.
From the patent application’s claims:
A method comprising: continuously, after entering a mode, capturing a sequence of images with an image capturing device…storing a predetermined number of the sequence of images in a buffer; receiving a user request to capture an image; and in response to the user request, automatically selecting one of the buffered images based on an image contrast parameter that compares pixel values within each buffered image, wherein the sequence of images were captured prior to receiving the user request.
Users of digital cameras built in to mobile devices are aware of a slight delay that occurs between previewing and framing a shot and the resulting image after pressing the shutter. As described by the patent, mobile devices have a “preview mode” that displays the camera’s input on the device’s screen at a lower resolution for framing purposes and a “capture mode” that is activated when the user presses the shutter and allows for full resolution output.
With current technology, there is an unavoidable delay between what the user sees in the preview window and what the camera captures at full resolution once the modes have been switched. During this delay, the scene could change, the position of the device could move, or the user’s hand could shake the camera, all resulting in potentially degraded image quality.
With a process described by the patent application, the camera would begin temporarily storing full resolution images automatically once the user opened the camera’s preview window. Then, once the user activates the shutter, the camera’s software and optional dedicated processing hardware automatically compares the captured frames to find those closest to the user’s desired exposure time using criteria such as contrast, dynamic range, sharpness, and color properties. The “best” image is then displayed to the user and, upon acceptance, the other captures stored in the buffer are deleted.
The process described is similar to that introduced by BlackBerry in its BlackBerry 10 camera app. As described by BlackBerry, its software also captures full resolution images once the user opens the preview window, and it allows a user to manually adjust an image, or parts of an image, to a previous frame. The company used the example of fixing a single subject’s closed eyes while leaving the rest of the image as it was captured. Apple’s process differs in that the buffering and selection occur automatically without user interaction.
The patent application, titled “Image Capturing Device Having Continuous Image Capture,” was filed on October 10, 2012 before being published today. It lists Ralph Brunner, Nikhil Bhogal, and James David Batson as inventors.