I'm working on a redesign for a daily news portal. And there is a huge doubt about using social sharing buttons on every picture of an article, is it good UX or is it too much, because every article has floating social sharing widget?
It can get complicated when you have a ton of images that have the same options for social networking. Pinterest actually has an interesting way of approaching this, rather than always having the buttons visible on each image all the time for social sharing, you can instead only have the social sharing buttons available on hover and have them not visible when they are not viewing or hovering over the image. This would allow you to have all the images enabled with social sharing but also keep your images clean without them constantly being plagued with social networking buttons.
So YES, keep it so that each image has social sharing options because it makes it easier for the user, but to keep it looking clean just have the buttons only appear ON HOVER, or when targeting the image specifically.
One thing I would ask is why users would need share buttons by every picture in the article. If it was a recipe site or an interior design site I could see a feature like that being very useful so that users could bring all their pictures together on sites like Pinterest - however for a daily news portal I don't see a user scenario where someone would want the option to share every image provided.
To answer your question more directly, I'd say don't give users that options. There are countless studies/anecdotes suggesting that users very rarely use social media share buttons (attaching 1 of the better articles that I found that demonstrates this but a quick google search will give you countless more).
I often find that even one set of social share buttons hinders my experience because it destroys minimal clean design and leaves a bunch of ugly squares in a corner.
That being said, the article I linked brings up some interesting pros to social share buttons:
There are some redeeming values to sharing buttons. A post with buttons that show thousands of shares definitely boosts credibility. It signals that there is quality content, and others are vouching for it. Simply having the buttons on the page also subtly reminds visitors that they should share the content.
This being said though, I think this is a double edged sword. If nobody shares the pictures you have buttons on, it's going to make for a very sad and pathetic site with low credibility if people see that nobody's sharing the things you've posted.
TL;DR: Social share buttons, from my experience and research, don't add very much value to a site. Should you decide to use them use them sparingly and beware that they can add credibility to an already popular article or they can make your article look sad and alone.