  Photo Response Non-Uniformity (PRNU) based source camera attribution is an
effective method to determine the origin camera of visual media (an image or a
video). However, given that modern devices, especially smartphones, capture
images, and videos at different resolutions using the same sensor array, PRNU
attribution can become ineffective as the camera fingerprint and query visual
media can be misaligned. We examine different resizing techniques such as
binning, line-skipping, cropping and scaling that cameras use to downsize the
raw sensor image to different media. Taking such techniques into account, this
paper studies the problem of source camera attribution. We define the notion of
Ratio of Alignment, which is a measure of shared sensor elements among
spatially corresponding pixels within two media objects resized with different
techniques. We then compute the Ratio of Alignment between the different
combinations of three common resizing methods under simplified conditions and
experimentally validate our analysis. Based on the insights drawn from the
different techniques used by cameras and the RoA analysis, the paper proposes
an algorithm for matching the source of a video with an image and vice versa.
We also present an efficient search method resulting in significantly improved
performance in matching as well as computation time.
