What effect does compressing an image file generally have on its data?

Compressing an image file primarily decreases the file size. This process removes some of the data from the image, which can lead to a smaller file that is easier to store and share. Compression algorithms reduce file size by simplifying or eliminating certain details in the image.

In the context of file formats, lossless compression retains all original data, ensuring no quality is lost, while lossy compression sacrifices some image detail for a more significant reduction in size. The reduced file size is especially beneficial for web use and storage because it lowers loading times and saves bandwidth.

Considering the other options, increasing data quality is generally not a direct result of compression. Adding more details would typically contradict the purpose of compression, as it focuses on reducing rather than enhancing data content. Making the image larger contradicts the fundamental principle of compression, which is to minimize the space the file occupies. Thus, the role of compression is directly aligned with decreasing file size, making that the correct choice.