Weighted Score Based Fast Converging CO-training with Application to Audio-Visual Person Identification
Xiaodong Duan, Nicolai Bæk Thomsen, Zheng‐Hua Tan, Børge Lindberg, Søren Holdt Jensen · 2017
One potential problem in real classification applications is that the amount of labeled training data is insufficient since it is usually time-consuming to label data manually. When multiple modalities are available, it is possible to train an initial classifier for each modality using a small amount of labeled data, and then re-train each classifier using unlabeled data associated with the labels generated from the other modalities. This can be achieved by the well-known CO-training algorithm. Assuming that two modalities are available, it only takes the information from the other modality but not that from the self modality into account when choosing data, which usually results in slow convergence of classification accuracy. This may make the CO-training procedure time-consuming. To overcome this, we present a novel modification to the original CO-training algorithm, which is concerned with how new samples are chosen at each iteration to re-train the classifiers in order to improve the convergence of classification accuracy. In our method, the new data is chosen based on the weighted scores which are generated from both modalities instead of only the scores from the other modality as in the original CO-training. We apply both the modified and original CO-training methods on multi-modal person identification task using speech and vision. Experiments on a publicly available database show that our method outperforms the original CO-training by a large margin, in terms of convergence of classification accuracy on a separate testing data set.