So, like how much of a problem is copyright-trolling really?

Setting aside the “moral” issue – on respecting the rights and interests of creative artists – given the zillions of blogs out there, including popular ones operated for a profit and still using whatever images they can find without even crediting the sources – you might not think it’s a big deal. I didn’t think so myself – until I found myself working at a site where the editors/administrators had received a demand letter from an aggressive “copyright-trolling” lawyer threatening to sue, demanding a settlement payment, and putting the future of the site itself in peril just for the costs of defending themselves legally. Seemed like a big deal to me as a developer when I discovered that the editor-in-chief, who didn’t really know what he was doing, had deleted whole image folders without even making a backup first…

OK, but how do we get good images for our site then?

Colleagues and I have had great experiences with ImageInject, a plugin by Thomas Hoefter and WPscoop that makes searching, using, and crediting images from Flickr and Pixabay easy – and fun. You can also do pretty well searching Wikimedia Commons. US government-produced images – like NASA images – are generally by definition in the public domain. You’re probably safe with old advertising and fine art, with publicity images generally, and often with screen captures used for critical purposes – i.e., to criticize [television station] for its coverage, but not to steal their images or graphics – but at that point you’re starting to get at gray areas and danger zones, as there are potential exceptions to every rule. The biggest danger seems to be using – stealing – images from aggressive, rights-protecting news photo vendors and also from individual creative artists. On the the other hand, there are a lot of photographers and artists out there who will grant a license to their work in exchange for a credit. Sometimes you can find them at places like DeviantArt. Then there’s always the option of creating your own illustrations…

…or, if you really, really want just the right professional-quality image you can even, gulp!, pay for it.

What’re “load errors” and “crawl errors,” and why should I care and not just go with a “lightweight” Javascript solution?

If you’ve found a Javascript solution that works for you as far as replacing broken images goes, maybe that’ll be fine! However, Javascript broken image solutions typically *do not* eliminate the errors they “fix.” In fact, they entirely depend on them to function. Leaving image errors in place will produce slow loads on affected pages, which may be bothersome to users going through your archives, and both the slower loads and the existence of the errors (both broken images and bad links) will (or are said to) harm your site’s Search Engine Rankings – more on load errors at “Comparative Page Loads with and without Image Errors“.

I think I set everything right, but, when I look at the results, the old images are still there! Why?

As noted elsewhere – for instance, under Usage Notes and in the description of this plug-in – you may need to clear (delete, purge, flush, etc.) site and other image caches, including Content Delivery Network caches. In some instances – for instance with JetPack’s Photon Module, which does not include a clearing option – de-activating it for a a couple of weeks seemed to solve the problem on re-activation, but this experience should not be taken as a guarantee: You may need to try some other CDN, or go without one for a while, if you want to use WP-RUBI.

You can also try restoring Photon or other problematic add-ons back after you’ve “cleared” your site, but check the results first to be sure that old images are not still displaying.

What if I just want to blank out all the old images, like they were never there?

Blank away: Use the provided 1 pixel by 1 pixel transparent image or select the “erase images” option. Doing so may leave unexplained gaps, dangling captions, and so on in your old posts, and will make picking them out visually more difficult when you’re working on them later, if you ever get to them, but that’s up to you (and you can change back and forth easily from the plug-in options page)!

OK, but what if I want to have one kind of replacement image for one type of post, and one for another, or randomly select from a gallery of images… and what if I want to divide up different time segments intead of just using one timespan, and.. and…

Let me know, and I’ll think about adding the capacities and options to a future version of the plug-in… or I guess we can discuss a custom job if it’s urgent! (Though that thing about selecting from a gallery you could already get if you linked to a “rotater” PHP file…)

Why do my old thumbnail images show up in different proportions from new ones in All Posts?

That would be because the new size for “Featured Preview” thumbnails is generated when a post is uploaded. If you’d like to generate the new size retroactively, because you’re kind of a stickler for that kind of thing, you might want to try the Regenerate Thumbnails Plugin.