Rapidly growing applications on smartphones have provided an excellent platform for mobile visual search. Most of previous visual search systems adopt the framework of ”Bag of Words”, in which words indicate quantized codes of visual features. In this work, we propose a novel visual search system based on ”Bag of Hash Bits” (BoHB), in which each local feature is encoded to a very small number of hash bits, instead of quantized to visual words, and the whole image is represented as bag of hash bits. The proposed BoHB method offers unique benefits in solving the challenges associated with mobile visual search, e.g., low transmission cost, cheap memory and computation on the mobile side, etc. Moreover, our BoHB method leverages the distinct properties of hashing bits such as multi-table indexing, multiple bucket probing, bit reuse, and hamming distance based ranking to achieve efficient search over gigantic visual databases. The proposed method significantly outperforms state-of-the-art mobile visual search methods like CHoG, and other (conventional desktop) visual search approaches like bag of words via vocabulary tree, or product quantization. The proposed BoHB approach is easy to implement on mobile devices, and general in the sense that it can be applied to different types of local features, hashing algorithms and image databases. We also incorporate a boundary feature in the reranking step to describe the object shapes, complementing the local features that are usually used to characterize the local details. The boundary feature can further filter out noisy results and improve the search performance, especially at the coarse category level. Extensive experiments over large-scale data sets up to 400k product images demonstrate the effectiveness of our approach.

The advent of smart phones has provided an excellent plat- form for mobile visual search. Most of previous mobile visual search systems adopt the framework of "bag of words",in which words indicate quantized codes of visual features. In this work, we propose a novel mobile visual search system based on "bag of hash bits". Using new ideas for hash bit selection, multi-hash table generation, and hamming-distance soft scoring, we overcome the problem of bit inefficiency affecting the traditional hashing approaches, and achieve promising accuracy outperforming state of the art. The framework is also general in that general feature type can be used for generating the hash bits. Demos and experiments over a large scale product image set demonstrate the effectiveness of our approach.

In this paper, we present a study of the realism of color image composites. Assessing the realism of image composites has emerged as a new field of image processing due to the advances in digital imaging and communications. However, when making image composites, users often suffer from color incompatibility between the inserted object and the background. We observe two properties that help make an image composite look realistic. The first property is related to the color similarity between different segments of the image, and the second one is related to the consistency of color deviation between the segments. These two properties only require information available from a single image. An algorithm based on these two properties is proposed for assessment of image realism. Effectiveness of the algorithm is demonstrated.

In this paper, we present a system including a novel component called programmable aperture and two associated post-processing algorithms for high-quality light field acquisition. The shape of the programmable aperture can be adjusted and used to capture light field at full sensor resolution through multiple exposures without any additional optics and without moving the camera. High acquisition efficiency is achieved by employing an optimal multiplexing scheme, and quality data is obtained by using the two post-processing algorithms designed for self calibration of photometric distortion and for multi-view depth estimation. View-dependent depth maps thus generated help boost the angular resolution of light field. Various post-exposure photographic effects are given to demonstrate the effectiveness of the system and the quality of the captured light field.