Eye tracking observers during color image evaluation tasks

Abstract

Eye movement behavior was investigated for image-quality and chromatic adaptation tasks. The first experiment examined the differences between paired comparison, rank order, and graphical rating tasks, and the second experiment examined the strategies adopted when subjects were asked to select or adjust achromatic regions in images. Results indicate that subjects spent about 4 seconds looking at images in the rank order task, 1.8 seconds per image in the paired comparison task, and 3.5 seconds per image in the graphical rating task. Fixation density maps from the three tasks correlated highly in four of the five images. Eye movements gravitated toward faces and semantic features, and introspective report was not always consistent with fixation density peaks. In adjusting a gray square in an image to appear achromatic, observers spent 95% of their time looking only at the patch. When subjects looked around (less than 5% of the time), they did so early. Foveations were directed to semantic features, not achromatic regions, indicating that people do not seek out near-neutral regions to verify that their patch appears achromatic relative to the scene. Observers also do not scan the image in order to adapt to the average chromaticity of the image. In selecting the most achromatic region in an image, viewers spent 60% of the time scanning the scene. Unlike the achromatic adjustment task, foveations were directed to near-neutral regions, showing behavior similar to a visual search task.