This research examines how and through what mechanisms candid versus posed modeling styles and contextual versus null backgrounds influence social media advertising evaluations/perception. Based on a study using controlled advertising stimuli, findings demonstrate that candid modeling style increases perceived model genuineness, and that natural contextual background increases narrative transportation effect, both processes leading to greater brand authenticity, which in turn elicits more favorable brand attitude. Serial mediation analysis (PROCESS Model 6) confirms that both perceived genuineness and narrative transportation play as key psychological mechanisms linking visual advertising cues to brand outcomes. The results highlight the importance of authentic visual strategies in social media advertising and extend understanding of how photographic features contribute to authenticity perception and persuasion toward successful marketing outcomes in an online environment.