Is there a programmatically way to force a crawler to not index specific images?
Building on top of what you had in mind, you could just create a separate place to keep the images that you don't want to be indexed, write a script to move files to that location once they're "expired" and just add the url to the the robots.txt file. Perhaps something like /expired_images*.
I want to stop crawlers from indexing specific images on my website, but only if they're older than a specific date. However, the crawler shall not stop indexing the page where the image is currently linked.
My initial approach was to write a script which adds the URL of the image to 'robots.txt', but I think the file will become huge, as we talk about a really huge amount of potential images.
My next idea was to use the <meta name="robots" content="noimageindex"> tag, but I think this approach can be error prone, as I could forget to add this tag to a template where I might want to stop crawlers from indexing the image. It's also redundant and the crawler will ignore all images.
My question is: do you know a programmatically way to force a crawler too not index a image, if a condition (in my case the date) is true? Or is my only possibility to stop the crawler from indexing the whole page?