the first picture you posted was at 720x480 (well, 479, but close enough)
anyway, the highest resolution standard televisions show is 720x486... that is what resolution our school is using to print our demo reels to tape as well...
so naturally, someone capturing a screenshot from the game, if their capture device is good enough, is going to be getting 720x486 images, or 720x480 images, it depends on the program capturing the images as well as the hardware. That explains why the Gamespot picture you posted is so big... btw, a non-widescreen tv is 640x480...
now... I've heard quite a few people talk about jaggies being more evident in screenshots than in the actual game... if you will remember my discussions on fields and all that stuff, that pretty much explains why there is more pixelation. if your capture device is top-of-the-line, your going to get a screen with fields visible in it. In otherwords, it'll look like crud unless you use photoshop or some other means to de-interlace the picture. Well, when you de-interlace the picture, you're taking every other line, in a scanline pattern, and copying it down to the pixels below the scanlines you took samples from. this in return makes the image look like it was 720x243 and then scaled 200% taller. so yes, harsh lines that look like bad anti-aliasing are going to be somewhat more noticeable.
in case anyone was wondering, fields are what enables 60-fps viewing on your tv. Ever wondered why some text, lines, or other graphics on a television seem to flicker and bounce around? that's because they're broadcasting an image that isn't properly formatted for fields... or that are too high resolution for tv... if there's a line that's only 1 pixel tall, it's going to seem to appear and disappear rapidly
but anyway, fields enable the 60-fps beacuse each image outputted to the television contains two frames... and based on my experience, lower feilds are rendered first by the tv, then upper feilds... so a video tape would have 30 frames per second, but the pictures are formatted so that the tv shows 60 frames per second, if that makes sense
this is also why no video game console will ever show stuff as smoothly as a computer can heh, unless hdtv's work more like a computer monitor
... anyway, back to my thoughts about what you've said...
I'm not sure about the ps2 using 640x520 images... that 4:3.25 ratio doesn't sound right... I doubt the ps2 outputs at anything different than 720x480, 720x486, 640x480, or 640x486, unless you're in HDTV modes...
also, no capture device that I know of can capture the stuff with absolutely no quality loss... so not only do you have the fields junk, but you've also got a bit less quality in the image as well. Whereas the developers can just take the game on the computers they've been developing it on, take a render from their 3d software, and release that, giving you shots like that one bamboo shot from gt4, or those shots of the cars in the tunnel in gta3, which there was also a wireframe render of that same picture
and that killzone pic...
cobragt wrote:

Can you honestly say you see a jag?
I'm sorry, but I see jags all over the place heh... fortunately none of them are really big enough to matter that much.
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Awww, ImageShack messed up my image from my signature outdated from 2008 >.>