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Back-to-back dual fisheye cameras are the most popular and cost-effective device to capture 360° images. However, inconsistent intensity and color between the pair of fisheye images often cause visible artifacts in the final 360° image. In this paper, we present a method to create photometric consistency between the two fisheye images. Specifically, we propose a loss function for image intensity compensation and a local color transfer model for color correction. Experimental results show that our method is able to correct the photometric inconsistency between dual fisheye images for high-quality 360circ imaging.

Video-based Heart Rate Measurement has drawn a lot of attention in recent years. A few papers have been proposed in this work and most of them applied Fourier transform peak interval determination method for heart rate measurement. However, the analyzing duration for one outcome in these methods is usually longer than 15 seconds. This is because that the measurement resolution in Fourier transform is proportional to the number of samples. In this paper, we apply a novel method to combine temporal-domain peak determination method and super resolution method for heart rate measurement. And we further propose a spectrum selection scheme and a data shift scheme to raise the measurement accuracy. The video database taken in our lab is used to evaluate the performance of the proposed method. The experimental results show two important things. The first is that when the analyzing duration of the proposed method is one third of Fourier transform, the precision of the proposed method is only a little lower than that of the Fourier transform method. Furthermore the precision of the proposed method is superior to Fourier transform approach when the analyzing duration is the same for both methods.

Spoofing attack (or copy attack) is a fatal threat for biometric authentication systems. In this paper, we present a novel liveness detection method based on frequency entropy of image sequences against the photograph spoofing. By splitting the color video of face region into RGB channels, we can obtain the time sequences of each color channel. Then, three RGB sequences are analyzed through Independent Component Analysis (ICA) algorithm to eliminate the cross-channel image noises. Moreover, the Fast Fourier Transform (FFT) is further applied to these signals to get the power spectra of each RGB channels. Finally, the power spectra are verified through the entropy calculation to validate the liveness or photo attack. The experimental results demonstrate the superiority of the proposed method, which has an accuracy of more than 95%.