Feature reconstruction by laplacian eigenmaps for efficient instance search

Instance search aims at retrieving images containing a particular query instance. Recently, image features derived from pre-trained convolutional neural networks (CNNs) have been shown to provide promising performance for image retrieval. However, the robustness of these features is still limited by hard positives and hard negatives. To address this issue, this work focuses on reconstructing a new representation based on conventional CNN features to capture the intrinsic image manifold in the original feature space. After the feature reconstruction, the Euclidean distance can be applied in the new space to measure the pairwise distance among feature points. The proposed method is highly efficient, which benefits from the linear search complexity and a further optimization for speedup. Experiments demonstrate that our method achieves promising efficiency with highly competitive accuracy. This work succeeds in capturing implicit embedding information in images as well as reducing the computational complexity significantly