“…The automatic image tagging or annotation problem is usually regarded as an image classification task. Typical techniques [2,4,7,9,11,12,14,16,20,28,29,33] usually learn a generative/discriminative multi-class classifier from the training data, to construct a mapping function from low level features extracted from the images to tags, and then predict the annotations or tags for the test images. Later, a more precise formulation is presented to regard it as a multi-label classification problem by exploring the relations between multiple labels [15,30].…”