Highlight exposure metric and its applications

摘要

Systems, methods, and computer readable media for the use of a metric whose value is especially sensitive to the information lost when an image's pixels are clipped are disclosed. The metric may be used as an image's score, where higher values are indicative of lost highlight information (more clipped pixels). One use of the disclosed metric would be to determine when the use of high dynamic range (HDR) techniques are appropriate. The disclosed metric may also be used to bias a scene's exposure value (EV) such as to a lower or underexposed value (EV−) so that the scene may be captured with no more than an acceptable number of clipped pixels.

主权项

1. A method to capture a digital image, comprising:
capturing a first image of a scene using a first exposure value, the first image having one or more channels; obtaining one or more metrics, wherein each metric corresponds to one of the one or more channels, and wherein the metrics characterize the first image; determining a clipped pixel number for each channel, wherein each clipped pixel number is based on the channel's corresponding metric; determining a highlight metric value based on a weighted combination of the clipped pixel number from at least one of the one or more channels; adjusting the first exposure value to a second exposure value based on the highlight metric value; capturing a second image using the second exposure value; and storing the second image in a memory.