Earlier quoted context omitted.
Unfortunately the images cannot be downloaded from Google Art Project (original name). It's irritating having to jump over complicated hurdles to get a seamless hi-res image capture from Google Arts. It requires some messing about, but I previously managed to grab about 100 high res images, but it took ages and was not easy. They printed out nicely in the end though, so was worth it. A simple download link as seen on…
I was deeply involved in the project for 5 years and the reason you can't download from it is because museum partners don't want you to. All the image security you find there comes from partner requests. If it's irritating, don't blame Google.
The word "security" can't be applied when the measures in place are "don't include a download link".
There is no "security" when the image displays perfectly fine on the screen. It just takes a few screens worth of panning, screen-grabbing and assembling a complete image in Photoshop. After a few rounds, I had a rather efficient workflow going using macros. Most of the artwork I was interested in was between 50 and 100 years old, and completely for personal use - printing out hi-res versions on paper of my choice (matte, never glossy like almost all commercial art prints.)