it's not enough, it doesn't give you the right to use these pictures. IANAL but this is common sense. Doesn't mean they'll go after you but it is certainly enough for a DMCA take down request. You don't need these pictures at first place anyway.
You don't have a license for those images, so you can't use them. Period.
Fair use only applies under certain circumstances where using copyrighted materials is necessary (e.g. satire or discussion). Even if you don't use them commercially, you can't just use them like that.
So how about all these slideshow presentations we see online (or videos of presentations, etc.) that use clips from movies, TV shows, memes, and so on? Are the copyrighted materials really necessary in those? I'd argue they're as necessary to a presentation as they are to a website, yet you never hear people on HN comment that the copyrighted material is out of place in those settings.
They would probably come under some commonly accepted exception such as homage, humour, demonstration, reporting, and so on. The examples currently on this page the images in question are part of the page design so are functioning as part of a derived work.
Distinctions like this are rather fuzzy, but I think this sits the other side of the line most people would draw then the pages you mention.
(For reference, dear reader, in case the pages changes between me writing this and you reading it, the linked page contains stills from Back To The Future used as background images.)
In some cases they probably are infringing too. But it seems worse in my opinion using copyrighted media as your main background for a promotional site. Putting a meme into a presentation slide, you may be right, it may also be legally infringement, but we kinda look the other way because it doesn't seem as promotional in nature.
> yet you never hear people on HN comment that the copyrighted material is out of place in those settings.
Some parts of HN don't make that kind of meta style comment because it's off topic for HN. But here it's a risk for the site owner - DMCA could remove their site - and so people mention it.
There are people who could mention copyright at every applicable opportunity and I'm glad that they don't. (Although I would like a place for that kind of comment! Also, tpyos).
Its a simplification, and not a very incorrect one. The purpose of Fair Use is to reserve for society those uses that benefit society more then they hurt copyright owners. Whether a use is "necessary", while not a legal definition, is a pretty good rule of thumb for some possible Fair Use defenses.
ETA: also this is completely ignoring any relevant international laws. French law, which is where the OP lives, appears to provide some protections for "necessary" use.
Necessity isn't a criterion for fair use, it's the reason fair use provisions exist in the first place.
Making satire of or discussing a copyrighted work without using copyrighted material is extremely awkward if at all possible. Internationally speaking (i.e. aside from the specific definition of fair use in US law), necessity is a good rule of thumb, just like profit/non-profit use.
it's not enough, it doesn't give you the right to use these pictures. IANAL but this is common sense. Doesn't mean they'll go after you but it is certainly enough for a DMCA take down request. You don't need these pictures at first place anyway.