text: We study the problem of Salient Object Subitizing, i.e. predicting the existence and the number of salient objects in an image using holistic cues. This task is inspired by the ability of people to quickly and accurately identify the number of items within the subitizing range (1-4). To this end, we present a salient object subitizing image dataset of about 14K everyday images which are annotated using an online crowdsourcing marketplace. We show that using an end-to-end trained Convolutional Neural Network (CNN) model, we achieve prediction accuracy comparable to human performance in identifying images with zero or one salient object. For images with multiple salient objects, our model also provides significantly better than chance performance without requiring any localization process. Moreover, we propose a method to improve the training of the CNN subitizing model by leveraging synthetic images. In experiments, we demonstrate the accuracy and generalizability of our CNN subitizing model and its applications in salient object detection and image retrieval.
  @cite_0: In robotics and computer vision, saliency maps are frequently used to identify regions that contain potential objects of interest and to restrict object detection to those regions only. However, common saliency approaches do not provide information as to whether there really is an interesting object triggering saliency and therefore tend to highlight needless background as potential regions of interest. This paper addresses the problem by exploiting histogram features extracted from saliency maps to predict the existence of interesting objects in images and to quickly prune uninteresting images. To validate our approach, we constructed a database that consists of 1000 background and object images captured in the working environment of our robot. Experimental results demonstrate that our approach achieves good detection performance and outperforms an existing existence detection approach [1].
  @cite_8: In this paper, we deal with the problem of detecting the existence and the location of salient objects for thumbnail images on which most search engines usually perform visual analysis in order to handle web-scale images. Different from previous techniques, such as sliding window-based or segmentation-based schemes for detecting salient objects, we propose to use a learning approach, random forest in our solution. Our algorithm exploits global features from multiple saliency indicators to directly predict the existence and the position of the salient object. To validate our algorithm, we constructed a large image database collected from Bing image search, that contains hundreds of thousands of manually labeled web images. The experimental results using this new database and the resized MSRA database [16] demonstrate that our algorithm outperforms previous state-of-the-art methods.
summary: Detecting the existence of salient objects. Only a few works address the problem of detecting the existence of salient objects in an image. @cite_8 use a global feature based on several saliency maps to determine the existence of salient objects in thumbnail images. Their method assumes that an image either contains a single salient object or none. @cite_0 use saliency histogram features to detect the existence of interesting objects for robot vision. It is worth noting that the testing images handled by the methods of @cite_8 and @cite_0 are substantially simplified compared to ours, and these methods cannot predict the number of salient objects.