Visual-based and object-conscious image retrieval by block reallocation into object region

‘Visual-based’ image retrieval based on the visual similarities over the entire image is one of the powerful and useful ways when targeting large volume content with inadequate annotation. Generally, conventional methods divide a query image and target images in the database into grid-shaped blocks and calculate the similarity based on image features by comparing each corresponding block straightforwardly. However, the method sometimes fails in terms of object-conscious retrieval when their backgrounds are almost the same but the only the object is different or the object's size and/or position is different. To solve the problem, we propose a new method featuring the reallocation of some blocks to the object region (OB-blocks) and a new similarity score by placing a weight on the OB-blocks, which are derived from the visual saliency map. Our proposed method could realize ‘visual-based and object-conscious’ image retrieval. We verify the effectiveness of this method through comparison experiments. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.