Method and apparatus to correct blur in all or part of a digital image by combining plurality of images

What is this patent about?

’740 is related to the field of digital image processing, specifically addressing the problem of motion blur. In traditional photography, relative movement between the camera and the subject during a long exposure results in a smudged or blurred image. This is particularly problematic in low-light conditions where slow shutter speeds are required to gather enough light for a usable exposure.

The underlying idea behind ’740 is to replace a single long exposure with a sequence of high-speed captures that are intelligently aligned and merged. By using a fast shutter speed for each individual frame, the system freezes motion to prevent blur within those frames. These sharp but potentially underexposed images are then computationally stacked to achieve the light-gathering benefits of a long exposure without the associated motion artifacts.

The claims of ’740 focus on a method and device that allow for selective blur correction based on a designated subject. The system identifies a specific object within a preview image—either automatically or via user input—and processes a plurality of captured images to ensure that this primary subject remains sharp in the final output. This is achieved by aligning the frames specifically to the movement of that subject, even if it results in the rest of the scene remaining blurred.

In practice, the invention functions by capturing images back-to-back at the fastest possible shutter speed the hardware allows. A processor then performs pixel-by-pixel alignment, shifting each frame in the series to compensate for the measured or detected displacement of the target subject. When these aligned frames are summed or averaged, the signal-to-noise ratio improves significantly, effectively simulating a longer exposure while maintaining high edge definition for the tracked object.

This approach differs from prior solutions, such as mechanical image stabilization, which physically move lens elements or sensors to counter camera shake. While mechanical systems only compensate for the photographer's hand movements, this invention can correct for the independent motion of subjects within the frame. Furthermore, by allowing a user to toggle between different subjects for correction, the system provides a level of post-capture compositional control that traditional hardware-based stabilization cannot offer.