Advanced: Best practices for quoting source of online image
The trick is to link to the best level - not too broad or too detailed. Let's use a couple of photos from Wellcome Images and Discuss.com.hk as examples.
1. Too broad - the site
You give the website as the source, eg:
Source: Wellcome Images
The problem is that each of these sites has thousands of images, so the reader has a hard time finding out any information about the photo.
2. Too detailed - the image file
You link to the image file, eg:
The link looks better, but in fact it's worse, as we still don't have any information about the photo or who posted it, and we can't even see that the photo was posted to the discuss.com.hk site.
3. Just right - the page where the image was first posted
For a library site like Wellcome Images, each image has a catalogue page that gives all the information about it that a reader needs. That's the best page to link to, eg
Source: Wellcome Images - http://catalogue.wellcomelibrary.org/record=b1187516
For discussion sites like discuss.com.hk or uwants.com, images are loaded directly into the discussions. We're looking for the first post that the image appears on, as that shows who uploaded it, eg:
4. Bonus tip - use text reference and link
Links often stop working over time, so if there's any reference shown, mention that too. eg on the page for the Wellcome Image above, I see:
Cite as Wellcome Library no. 29675i
Even if the link stops working, it should be possible to track down the photo if we know the reference number "29675i", eg:
Source: Wellcome Images - their ref: 29675i - http://catalogue.wellcomelibrary.org/record=b1187516