The JPEG markers contain SOFn for start of frame and SOS for start of scan. What do the two items mean and what is the connectio between them?
In the JPEG modes that are actually used in the real world——
A Frame is the image. The SOFn market describes the format of the image.
A Scan is a single pass through the image data. In a grayscale image processed sequentially, there will be one scan in the frame.
In a color frames processed sequentially and noninterleaved, there will be three scans in the frame, one for each color component.
In a progressive JPEG frame, there can be a multitude of scans in a frame.