I have redesigned one of the pages of a website I'm current working on, and some of the images on this website, 2 to be exact, rank on the very first page of public google search results.
Those pictures are okay, but have a nasty looking background, look a bit blurried. I removed the background, did a bit of work on them and they are better now.
All of the other pictures are also indexed by google but don't rank so well.
I have found that certain file naming techniques worked better for ranking than the ones previously used for all those images for example, so since that page was redesigned, I have a couple of alternatives:
1 - Leave the old files on the server, and don't use them. Name the new ones the correct way and hope they rank better. (Old pictures would probably not be listed on newer sitemaps, since are not linked to, which may cause rank loss?!)
2 - Name the new files the exact same name as the old ones, discarding the old files (They would be the same image in most cases, but cleaned up).
3 - Name the new files with new names, 301 redirect old files to new ones.
What's the best alternative to achieve best results?