Laboratory testing of the ultraviolet protection factor (UPF) provided by fabrics normally utilizes a collimated source of UV radiation and either a broadband sensor or spectroradiometer to detect the radiation, both unattenuated and after passing through the fabric sample held in a flat tensionless state. We report the results of an in vivo study of UV transmission through various T‐shirts at several sites on the trunk and arms of a life‐size mannequin irradiated with diffuse radiation and using UV sensitive polymer films as the sensor. We found a variation in UPF by a factor of two or more at different anatomical sites for a given T‐shirt, with lower UPFs seen at sites where the fabric is stretched; and found that at every site and for each T‐shirt this in vivo UPF was higher than the conventional in vitro UPF determined using collimated radiation.

To create a realistic 3D perception on glasses-free displays, it is critical to support continuous motion parallax, greater depths of field, and wider fields of view. A new type of Layered or Tensor light field 3D display has attracted greater attention these days. Using only a few light-attenuating pixelized layers (e.g., LCD panels), it supports many views from different viewing directions that can be displayed simultaneously with a high resolution. This paper presents a novel flexible scheme for efficient layer-based representation and lossy compression of light fields on layered displays. The proposed scheme learns stacked multiplicative layers optimized using a convolutional neural network (CNN). The intrinsic redundancy in light field data is efficiently removed by analyzing the hidden low-rank structure of multiplicative layers on a Krylov subspace. Factorization derived from Block Krylov singular value decomposition (BK-SVD) exploits the spatial correlation in layer patterns for multiplicative layers with varying low ranks. Further, encoding with HEVC eliminates inter-frame and intra-frame redundancies in the low-rank approximated representation of layers and improves the compression efficiency. The scheme is flexible to realize multiple bitrates at the decoder by adjusting the ranks of BK-SVD representation and HEVC quantization. Thus, it would complement the generality and flexibility of a data-driven CNN-based method for coding with multiple bitrates within a single training framework for practical display applications. Extensive experiments demonstrate that the proposed coding scheme achieves substantial bitrate savings compared with pseudo-sequence-based light field compression approaches and state-of-the-art JPEG and HEVC coders.

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