On occasion when using Safari on my iPad or iPhone, I find a web page that has some content of interest.
I could just save the whole web page to my Evernote (which is usually what I would do), but I have found an app that makes it really easy to grab just a small part of the web page and save it as an image - either to my Camera Roll or to some other app like my Evernote. I can even 'draw on' the image before I save it.
It is called Awesome Screenshot for Safari, a free app for iPhone and iPad that includes an 'Extension' for Safari that can be accessed from the 'Share' option when you are using Safari.
Watch this video to see how it works.
If you have downloaded and installed Awesome Screenshots, but you don't see the 'Screenshots' option in your Share menu, it may be because it has not yet been 'enabled' as one of your list of 'Activities'. (Also make sure that you are running iOS 8.)
Just tap on the More option in the second row on options and 'turn on' ScreenShot, then tap Done (top right)