Websites that allow users to search for posters based on color are designed to help users find images that match specific color schemes or palettes. These platforms typically use image recognition technology to analyze the color composition of each poster and categorize them accordingly. Examples include 'ColorZilla' for web designers to find color palettes, and 'Pexels' which allows users to filter images by color. These tools are useful for graphic designers, artists, and anyone looking for visually consistent content.