When it comes to describing contrasting elements within an image or text, there are a variety of synonyms for the term "highlight contrast." One option is to use the phrase "sharp contrast," emphasizing the stark differences between two or more objects. Alternatively, you might employ the term "striking difference," to suggest that the disparity between two items is particularly noticeable. Another useful synonym for "highlight contrast" might be "bright opposition," which speaks to the vividness and clarity of the comparison being made. Ultimately, the choice of terminology will depend on the specific context in which you are discussing the contrast and the emphasis you wish to place on certain aspects of the comparison.