Factors that Influence PRNU-Based Camera-Identification via Videos.

Lars De Roos,Zeno Geradts

doi:10.3390/jimaging7010008

Abstract

The Photo Response Non-Uniformity pattern (PRNU-pattern) can be used to identify the source of images or to indicate whether images have been made with the same camera. This pattern is also recognized as the “fingerprint” of a camera since it is a highly characteristic feature. However, this pattern, identically to a real fingerprint, is sensitive to many different influences, e.g., the influence of camera settings. In this study, several previously investigated factors were noted, after which three were selected for further investigation. The computation and comparison methods are evaluated under variation of the following factors: resolution, length of the video and compression. For all three studies, images were taken with a single iPhone 6. It was found that a higher resolution ensures a more reliable comparison, and that the length of a (reference) video should always be as high as possible to gain a better PRNU-pattern. It also became clear that compression (i.e., in this study the compression that Snapchat uses) has a negative effect on the correlation value. Therefore, it was found that many different factors play a part when comparing videos. Due to the large amount of controllable and non-controllable factors that influence the PRNU-pattern, it is of great importance that further research is carried out to gain clarity on the individual influences that factors exert.

Highlights

Each camera creates a highly characteristic pattern: The Photo Response Non-Uniformity pattern (PRNU-pattern)
For interpreting the figures that can be found in the results this information may be relevant: the highest and lowest correlation values are indicated in each figure, these are the values of mutual comparisons of images from the same telephone
The negative result relates to the lowest correlation value that came from a mutual comparison between two images of the same telephone

Summary

Introduction

Each camera creates a highly characteristic pattern: The Photo Response Non-Uniformity pattern (PRNU-pattern). This study made an overview of the factors already investigated Based on this list of more than 50 different factors, three factors were chosen that could contribute to the broadening of knowledge regarding the factors that influence the PRNU-pattern. These factors include the following: compression, resolution and the length of the video. In this report the investigation regarding Snapchat serves as a starting point for further investigations In addition to this partial study, the influence of resolution on the PRNU-pattern is being investigated. This paper looks at three different factors that can influence the PRNU-pattern and with that the correlation value that comes from the comparison of these PRNU-patterns

Objectives

Methods

Results

Discussion

Conclusion