Multidimensional spatio-temporal filters for depth-velocity filtering in light field videos

A novel multidimensional spatio-temporal signal processing algorithm is proposed for depth-velocity filtering in 5-D light field videos along with a tutorial review of light field video spectra and the general architecture of associated 5-D depth-velocity filters. A 5-D FIR filter having a hyperfan-shaped passband which can selectively enhance the spectra of moving objects in light field videos based on their depth and motion trajectory is employed. A 5-D hyperfan-shaped passband is highly desired to achieve enhanced spatio-temporal selectivity over a wide range of lower frequencies. Experimental results are provided by using a light field videos captured using a Lytro light-field camera and mean structural similarity index is used to verify the effectiveness of the proposed 5-D FIR hyperfan depth-velocity filter

A 4-D sparse FIR hyperfan filter for volumetric refocusing of light fields by hard thresholding

A low-complexity 4-D sparse FIR hyperfan filter is proposed for volumetric refocusing of light fields. By exploiting the partial separability of the spectral region of support of a light field, the proposed filter is designed as a cascade of two 4-D hyperfan filters. The sparsity of the filter coefficients is achieved by hard thresholding the nonsparse filter coefficients. The experimental results confirm that the proposed 4-D sparse FIR hyperfan filter provides 72% mean reduction of computational complexity compared to a 4-D nonsparse FIR hyperfan filter withoudeteriorating the fidelity of volumetric refocused light fields. In particular, the mean structure similarity (SSIM) index between the volumetric refocused light fields by the proposed sparse filter and the nonsparse filter is 0.989

Improving the attenuation of moving interfering objects in videos using shifted-velocity filtering

Abstract Three-dimensional space-time velocity filters may be used to enhance dynamic passband objects of interest in videos while attenuating moving interfering objects based on their velocities. In this paper, we show that the attenuation of interfering stopband objects may be significantly improved using recently proposed shifted-velocity filters. It is shown that an improvement of approximately 20 dB in signal-to-interference ratio may be achieved for stopband to passband velocity differences of only 1 pixels/frame. More importantly, this improvement is achieved without increasing the computational complexity

Multi depth-velocity filters for enhancing multiple moving objects in 5-D light field videos

A moving object in a five-dimensional (5-D) light field video (LFV) can be selectively enhanced using the depth and the velocity of the object. In this paper, a 5-D depth-velocity (DV) filter is proposed to enhance multiple moving objects at different depths and with different velocities in an LFV. The 5-D DV filter is designed as a cascade of an infinite-extent impulse response multi-depth filter and a finite-extent impulse response multi-velocity filter. Experimental results obtained with numerically generated and real LFVs indicate that more than 15 dB improvement in signal-to-interference ratio can be achieved with the proposed 5-D multi DV filter compared to previously proposed multi depth-only filters