Right now, many are saying the increase in graphical quality between the PlayStation 3 and PlayStation 4 isn't exactly mind-numbingly huge.
And in my estimation, that's true. I think the this generation has undoubtedly seen the smallest jump in terms of visual prowess. But if that's true, which PlayStation era showed us the biggest jump?
I still say it's the PS2. It was just ridiculous to see PS2 games after five years of original PlayStation games; the level of detail and clarity was just so far beyond that of the previous generation. Even the best PS1 games were still heavily pixelated (almost to the point of comedy, if I remember correctly), and 3D worlds hadn't fully come into their own. The PS2 was just so revolutionary from a technological standpoint, and that showed immediately from day one.
Don't get me wrong, I think the leap from the PS2 to the PS3 was pretty damn significant, too. Resistance: Fall of Man was amazing enough to make you go, "Woah…this is way more advanced." I mean, I'd actually say that in regards to certain aspects of graphics presentations, the PS3/PS2 jump rivaled the PS2/PS1 increase. But all in all, when you take everything into account, you were truly, undoubtedly, absolutely looking at a new generation of video games when you first saw the PS2. Leaps and bounds ahead of the system that came before it.
Of course, if we're going outside the PlayStation realm, you'd probably have to say SNES to N64 just because of the 3D revolution, or the Saturn to the Dreamcast (there wasn't any other Sega machine in between, was there?).