What is the purpose of a progressive JPEG format?

The purpose of a progressive JPEG format is to load a low-quality image initially and improve the quality as more data is received. This works by first displaying a lower resolution version of the image, which allows the viewer to see a basic representation of the picture right away. As additional data is downloaded, the image progressively refines itself, resulting in clearer details and a higher resolution over time. This progressive loading technique enhances the user experience, especially in situations where bandwidth may be limited, as it provides immediate visual feedback while the rest of the image continues to download.

This stands in contrast to other image formats, which may not offer this progressive loading ability. The enhancements to the number of colors in an image, the line-by-line display of images, or the focused reduction of load time for static images do not specifically address the core functionality of progressive JPEGs, which revolves around the gradual improvement of image quality during the loading process.