Visual saliency of character feature in an image

Visual saliency map has been proposed as a computational model for estimating the visual attention of a human. The saliency map is used to estimate the bottom-up visual attention for still and moving images. However, under the condition including the top-down visual attention, e.g. advertisement, the accuracy of visual attention estimated from the saliency map decreased. The character feature is considered as one of the factors that the deterioration of the saliency map accuracy is induced. In this study, we hypothesized that the features of characters have the saliency to induce the visual attention. Two types of experiments were performed to test this hypothesis. The still images inserted with both of characters (HIRAGANAs in Japanese or Thai strings) and simple symbols were used as visual stimuli in the experiments. The visual stimuli were presented to the subjects for a short period (2s) to exclude the effect of top-down attention. In result, the fixation probability of the character (both HIRAGANAs and Thais) region in the image was higher than that of the symbol region. The paired t-test provided the significant difference of the fixation ratio between HIRAGANAs and symbols (p < 0.001). The same is true for the paired t-test between Thais and symbols (p < 0.001). Thus, the present results indicate the visual saliency of characters.