Reduce file size of images on blog; convert PNG to JPG

Most images on the blog are PNG and very large file size for the web. They make browsing the blog particularly bad for mobile and in situations where internet speed is low, throttled, or capped. Most of the images do not need the clarity of a PNG and would remain visibly understandable as a smaller file size JPG. You can archive PNGs that you think you might edit in the future, but don't embed large file sizes on high-traffic pages, particularly not in the headers of blog posts. Convert them to JPG except for the few that absolutely cannot be visibly understood in a lossy compression format.