Abstract
For a painterly depiction to be convincing, the distal world does not need to be captured perfectly: a stylistic depiction that does not adhere to the statistical regularities found in the distal world can nevertheless be perceptually convincing. Understanding which highlight features are, or are not, required in order to trigger robust, convincing gloss perceptions is vital to understand human gloss perception. Here we study highlights on drinking glasses as depicted in paintings and compare these to their equivalent in photos. Four participants annotated highlights on drinking glasses in photos (n=55) and paintings (n=55). Paintings were sourced from the Materials In Painting (MIP) dataset, and photos were sourced from the COCO dataset. We found that highlights in paintings appear in a strong, stylistic pattern in the same canonical location(s), which was not found in photos. Furthermore, we found that highlights in paintings are less ambiguous, measured as annotator agreement. Spherical glasses (e.g., wineglasses) in paintings typically display a highlight on the rim in the top-left, and one caustic reflection in the bottom right. Conical glasses (e.g., martini glasses) typically display a stretched highlight from the top to the stem of the glass. For photographs we found that the highlights varied much in location and pattern. The current study is limited to a relatively small section of glossy objects but demonstrates the benefits of annotating highlights on a broader range of glossy objects, which can lead to a better understanding of higher level (pattern) cues for convincing material communication.