Locally linear salient coding for image classification

Representing images with their descriptive features is the fundamental problem in CBIR. Feature coding as a key-step in feature description has attracted the attentions in recent years. Among the proposed coding strategies, Bag-of-Words (BoW) is the most widely used model. Recently saliency has been mentioned as the fundamental characteristic of BoW. Base on this idea, Salient Coding (SaC) has been introduced. Empirical studies show that SaC is not able to represent the global structure of data with small number of codewords. In this paper, we remedy this limitation by introducing Locally Linear Salient Coding (LLSaC). This method discovers the global structure of the data by exploiting the local linear reconstructions of the data points. This knowledge in addition to the salient responses, provided by SaC, helps to describe the structure of the data even with a few codewords. Experimental results show that LLSaC obtains state-of-the-art results on various data types such as multimedia and Earth Observation.