Notice also that the background is not even. This is another reason to make a flat field adjustment. The next image shows the correction. This is what the image looks like with both the dark and flat corrections. A more sophisticated series of flat field corrections can be made, but it isn't worth the effort for normal pictures.
Further processing is needed to produce a good image.
This is an algorithm that analyzes the star images and adjusts the image to account for atmospheric distortions. Too much processing results in mottled backgrounds and other undesirable features. This can be minimized by taking a series of images and averaging them. The final image is shown below. There were a total of five images that were processed in the above manner.