Well, you are probably right about the compression artifacts. So I did some study on them this afternoon. While they mention boxes and squares and other artifacts, I saw nothing about small circles, long straight lines, irregular rectangular pieces, etc. I also ran the image through a different processing program, Photo See, and got the exact same patterns, so it is not just Photoshop creating the patterns, if that is what you mean. But what do I know? Has somebody else tried on their computer to duplicate what I did? And, I've gone through other ESA images at about the same resolution, and find no evidence of image compression there.

J.P.