Caching photos for one day

I have a site with pictures that change frequently. I want to be able set cache time for one day. I’ve seen plenty of examples to disable caching. I don’t want the user to have to reload every page every time. I want the page to expire at the end of the day. Is there anything that returns the date in a format that the
HTML meta expires can read

Like: meta http-equiv= ‘Expires” content= Date()

Photos are cached by browser by default based on image path. You only need to do something like this if you will serve another image with the same path (which is very bad idea aside from caching)

On phones when I update a photo, I have to go into the phone and clear the data for the site, otherwise it shows the old photo. I guess I am using the same path because I’m changing the photo. It’s for a site that displays their work and want to change the photos from time to time to show new work. I want to just pop in a new photo of the same name and not change any code.