We have a requirement on the main to give attribution for quotes and text from other sources.
However, in some cases a question needs an image to help clarify what is wanted.
According to an answer from Mod Andrew Leach addressing "new attribution rules" (2014), we should be giving attribution to images also.
"new attribution rules" apply specifically to quoted material. A simple link to further reading does not require attribution, but where there is material reproduced from elsewhere it is not sufficient merely to provide a link. A comment has reminded me that "quoted material" need not always be textual. The rules apply to text and images.
Meta: if it's obvious where material has been quoted from, perhaps because there is a link to it, then by all means edit the post to include the source in plain text.
Now some may think it is sufficient to provide a link to the website using those images, but it is possible that may not be enough. Many blog posts and amateur websites post images "borrowed" from the web via Google image search, and often do not give attribution, or they strip the meta-data.
[For those of you who do not know how to find image info, hover the cursor over the image, right click and then select "view image info"...If you want to see meta-data on an original image, use an exif viewer such as Opanda. Meta-data for your own images is available in "properties".](Windows users only...I don't use Linux or Apple OS)
I think what is messing some people up here is the difference between imprinting a "watermark" on an image, (like a Getty Photos, or ShutterStock image), and a copyright for an image. All image copyrights are due to the original author, unless sold. Professionals post a copyright in the original meta-data, also.
The following is an example of a properties search on an image included in a popular question of the moment. Notice it is marked "Associated text: image taken from the TV programme "Restoration Man". From what I understand of copyright law, that is the author.
This next is an example of meta-data of an original foto in an exif reader: notice that it has the author listed as "artist", and it is copyrighted 2017.
This is an example of the information available of a thumbnail with stripped data. Beyond the dimensions, nada..
Even here on SE, there are violations of users copyrights...
Context: I encountered an image I made (which was fully copyrighted and published in a blog post) in an answer here on the StackExchange network. The user luckily had his email in his profile and we resolved it without any issue. Still the fact that this happened and that the user in question had no idea that he had just published the image under a CC license felt wrong. I mean, I personally wouldn't mind publishing that image under a CC license (like with all my content on SE), but that should be my decision, not somebody's elses.
Without playing the "blame game", or "name and shame", I think there are many of us here who have done this. We tend to see any image we scoop up in Google to be fair game, and view it as public domain.
Why are people not giving a separate attribution to images in plain text, or is the image info and/or meta-data considered good enough, as it usually contains a link to the source and author?