Which feature of an image file refers to how data is compressed and impacts the quality and size of pictures?

The feature of an image file that refers to how data is compressed and impacts the quality and size of pictures is the file format. Different file formats use various compression algorithms, which can significantly affect both image quality and file size. For instance, formats like JPEG use lossy compression, which reduces file size by discarding some image data, which can lead to a decrease in quality. In contrast, formats like PNG employ lossless compression, which maintains the original quality but typically results in larger file sizes.

Understanding the implications of file formats is crucial for photographers, as the choice of format can influence storage requirements and how images appear when viewed or printed. This makes the file format pivotal in balancing quality and size based on the intended use of the images.