While advanced foundation models like ModernBERT significantly outperform older architectures in dense retrieval, they surprisingly lag behind the aging BERT-base baseline in learned sparse retrieval (LSR). We identify the root cause as the Vocabulary Gap : modern tokenizers utilize raw, case-sensitive vocabularies designed for lossless reconstruction, which map single semantic units to redundant surface forms, wasting model capacity on morphological noise and hindering lexical matching. We formalize this intuition through a theoretical framework, demonstrating that appropriate vocabulary coarse-graining can tighten the generalization bounds by reducing complexity of the hypothesis class, provided that semantic integrity is preserved. To resolve this, we propose Vocabulary Transfer (VT), a model-agnostic framework that migrates advanced encoders to sparse-friendly, normalized vocabularies with minimal computational cost. VT utilizes a novel Semantic Initialization via spatial topology to preserve geometric structure and an Activation Potential Calibration (APC) mechanism to align pre-trained manifolds with sparsity constraints, preventing the dead neuron and dense collapse observed in standard fine-tuning. Empirically, VT is universally effective: it enables ModernBERT to achieve state-of-the-art performance on the BEIR benchmark (52.4 nDCG, a +4.7 improvement), resuscitates failing models like RoBERTa-large, and generalizes seamlessly to inference-free architectures and specialized domains. These results confirm that the performance lag is not an architectural deficiency but a solvable vocabulary mismatch. We've released our code and models. https://anonymous.4open.science/r/vocab-transfer/. All details included.

Music search at the scale of Amazon Music presents a unique challenge: queries frequently deviate from indexed metadata due to misspellings, transpositions, and phonetic variations, yet the retrieval system must operate under strict millisecond-level latency constraints. Our existing learning-to-retrieve system, the High Confidence Index (HCI), learns query-entity associations from customer behavior, relying on continual "exploration" to choose candidates. Traditional n-gram matching enables this exploration but suffers from poor semantic robustness and high noise, limiting the system's ability to learn from long-tail queries. In this work, we present a robust neural sparse retrieval system designed to maximize exploration efficiency. We adapt a state-of-the-art inference-free sparse retrieval architecture to the music domain, combining it with an effective domain-specific granular subword tokenization strategy. Our approach utilizes short-length token constraints (max 3 chars) to enforce the learning of surface-form robustness over lexical memorization. By pre-computing the neural embeddings and term expansions during the offline indexing phase, online processing is reduced to minimal tokenization and IDF weighting, achieving effectively zero latency overhead for query encoding. Evaluations on a 6M-document production corpus show an aggregate 91.4% recall@10 (vs. 57.7% for trigrams) at comparable throughput. Simulation of the HCI feedback loop demonstrates improved exploration efficiency, with +0.8% higher stabilized recall than production trigrams. Ablation studies indicate that our sparse training methodology drives the performance gains, while domain-specific pretraining provides a cost-effective alternative to large-scale general-purpose pretraining.

With increasing demands for efficiency, information retrieval has developed a branch of sparse retrieval, further advancing towards inference-free retrieval where the documents are encoded during indexing time and there is no model-inference for queries. Existing sparse retrieval models rely on FLOPS regularization for sparsification, while this mechanism was originally designed for Siamese encoders, it is considered to be suboptimal in inference-free scenarios which is asymmetric. Previous attempts to adapt FLOPS for inference-free scenarios have been limited to rule-based methods, leaving the potential of sparsification approaches for inference-free retrieval models largely unexplored. In this paper, we explore ℓ0 inspired sparsification manner for inference-free retrievers. Through comprehensive out-of-domain evaluation on the BEIR benchmark, our method achieves state-of-the-art performance among inference-free sparse retrieval models and is comparable to leading Siamese sparse retrieval models. Furthermore, we provide insights into the trade-off between retrieval effectiveness and computational efficiency, demonstrating practical value for real-world applications.

Recent years, the stereo image has become an emerging media in the field of 3D technology, which leads to an urgent demand of stereo image retrieval. In this paper, we attempt to introduce a framework for object-based stereo image retrieval (OBSIR), which retrieves images containing the similar objects to the one captured in the query image by the user. The proposed approach consists of both online and offline procedures. In the offline procedure, we propose a salient object segmentation method making use of both color and depth to extract objects from each image. The extracted objects are then represented by multiple visual feature descriptors. In order to improve the image search efficiently, we construct an approximate nearest neighbor (ANN) index using cluster-based locality sensitive hashing (LSH). In the online stage, the user may supply the query object by selecting a region of interest (ROI) in the query image, or clicking one of the objects recommended by the salient object detector. For the image retrieval evaluation we build a new dataset containing over 10K stereo images. The experiments on this dataset show that the proposed method can effectively recommend the correct object and the final retrieval result is also better than other baseline methods.

Image search reranking and image research result summarization are two effective approaches which enhance text-based image search results using visual information. Since the existing approaches optimize search relevance in terms of average performance, they usually cannot achieve satisfactory results for some particular classes of queries, like “object queries,” which is defined as the queries with the intent of searching for some kinds of objects. One possible reason is that the generic approaches such as , , are mostly built based on the global statistics of images as features while ignoring the fact that the relevance between the image and the query sometimes depends on an image patch instead of the whole image. In this paper, we therefore design a novel bag-of-object retrieval model to predict image relevance, which is particularly effective for object queries. First, we construct an object vocabulary containing query-relative objects by mining frequent object patches from the result image collection of the expanded query set. After representing each image as a bag of objects, our retrieval model can be derived from a risk-minimization framework for language modeling. To demonstrate the effectiveness of the proposed model, this paper also present two related applications: for image search reranking, we adopt a supervised framework to combine multiple ranking features from different assumptions; for image search result summarization, we propose a two-step ranking process which optimizes not only representativeness but also image attractiveness. The experimental results show that the proposed methods can significantly outperform the existing approaches.

Image retargeting aims to avoid visual distortion while retaining important image content in resizing. However, no single image retargeting method can handle all cases. In this paper, we propose a novel multi-operator image retargeting approach, which utilizes an efficient and human perception based automatic quality assessment in operator selection. First, we calculate the importance map and distortion map for quality assessment. Then, we construct the resizing space and assess the performance of each operator in iterative width and/or height reduction. Finally, we select the optimal operator sequence by dynamic programming and generate the target image. Experiments demonstrate the effectiveness of the proposed approach.

In this paper, we propose an effective local stereo matching method based on extended triangular interpolation. The whole image is covered with a triangular mesh by performing triangulation on a set of initial support points. Since the disparity interpolation in some areas is ineffective, especially in the triangle which appears across the boundaries of objects or is formed by initial matching outliers, we formulate a new matching model based on the Bayesian rule to address this challenge. In the model, we introduce the concept of the triangle's reliability, and utilize the disparity planes determined by the neighboring triangles as the Bayesian prior. With the model, the disparity interpolation can be effectively performed. Experiments on the standard stereo data sets show that the method is effective, especially in dealing with the boundaries of objects.

Image search reranking has been an active research topic in recent years to boost the performance of the existing web image search engine which is mostly based on textual metadata of images. Various approaches have been proposed to rerank images for general queries and argue that, they may not necessarily be optimal for queries in specific domain, e.g., object queries, since the reranking algorithms are operated on whole images, instead of the relevant parts of images. In this paper, we propose a novel bag-of-objects retrieval model for image search reranking of object queries. Firstly, we employ a common object discovery algorithm to discover query-relevant objects from the search results returned by text-based image search engine. Then, the query and its result images are represented as a language model on the query relevant object vocabulary, based on which the ranking function can be derived. As the common object discovery is unreliable and may introduce noises, we propose to incorporate the attributes of the discovered objects, e.g., size, position, etc., into the ranking function through a linear model, and the weights on the object attributes can be learned. The experiments on two subsets of Web Queries dataset comprising object queries demonstrate that our approach can significantly outperform the existing reranking methods on object queries.

As dissolve is the most common gradual shot transition, dissolve detection plays an important role in video segmentation which is the fundamental step for efficient video indexing and retrieval. However, the existing detection methods easily confuse dissolve with camera motion or object motion when using global features. Besides, when using local features' change tendency, they can' t get accurate trajectories to reflect this. In this paper, we propose a SURF feature based dissolve detection algorithm which can well differentiate dissolve from motion appearances. We get the trajectories of SURF key points by matching between two successive frames. Then a candidate set of dissolves is obtained according to the distribution of the starting points and ending points on the trajectory, filtering part of motions. Dissolves are further located by analyzing the curve of the proportion of subtrajectories with monotonous variation through each frame. Experiments demonstrate the effectiveness and efficiency of the proposed method.