Home About Us Laboratory Services Forensic Science Communications Back Issues January 2009 research Figure 17: Correlation of denoised c2 Canon...

Figure 17: Correlation of denoised c2 Canon SD200-2 images with reference patterns from all of the cameras

Figure 17: Correlation of denoised c2 Canon SD200-2 images with reference patterns from all of the cameras

Correlation of denoised c2 Canon SD200-2 images with reference patterns from all of the cameras

This figure depicts the correlation of pattern noise extracted from the denoised images from camera c2 with 11 reference patterns. The correlation values with camera c2’s reference pattern are depicted using small green asterisks. Correlations, rho, are displayed on the y-axis, while the index of the image being correlated is displayed on the x-axis. The pattern is depicted as a smattering of the symbols, which range from 0.10 on the y-axis and 1 on the x-axis to .015 on the y-axis and approximately 425 on the x-axis. The correlations with camera c2’s reference pattern are centered on approximately 0.09 for the first 200 images (1 through 200 on the x-axis) because these images were also used to generate the reference pattern. The remaining images, 201 through 425, have slightly lower correlations centered on approximately 0.03. But even these correlation values are still significantly greater than the correlation values with other camera reference patterns. Comparing with Figure 8, the correlation values for images that have undergone malicious processing by removing the noise are less than the correlation values when compared with unprocessed images. Even then the classification accuracy remains close to 99 percent. The images having the smallest correlation with camera c2’s reference pattern (such as approximately 410 on the x-axis) are those of the night sky or similarly dark scenes. Camera c2 is a Canon PowerShot SD200.