How good the Samsung PS51E490's pictures are depends more than usual on what you feed it. Starting with the good news, it's much more assured than you've really any right to expect for its money when fed with HD sources.
The most surprising of its strengths with Blu-rays is the sharpness with which it reproduces HD's high-resolution images. From a sensible viewing distance it's extremely hard to spot any tell-tale signs that the panel isn't sporting a Full HD pixel count. Edges look crisp, textures look rich, and there are no really obvious signs of any downscaling processing going on.
If you really look hard and get up close and personal with the screen then you can make out a touch of softness in some very textured areas of HD pictures, and the occasional marginal colour error. But these issues aren't nearly severe enough to make us suggest even for a minute that the Samsung PS51E490's non-Full HD native resolution sells HD significantly short.
The Samsung PS51E490's clarity relative to most of the affordable flatscreen TV scene also owes a considerable debt to plasma's innate ability to reproduce motion without losing resolution. There's a bit of judder around, especially with 3D, but this is preferable to the blurring and even smearing often witnessed over motion on budget LCD TVs.
HD pictures also enjoy a strong colour performance. Tones look pleasingly vibrant and enjoy a surprisingly wide range for such a cheap TV, plus the set is as comfortable at rendering relatively subdued, dark colours as it is bright, punchy ones.
There is occasionally a touch of blocking with skin tones and some minor striping over subtle colour blends, but no more than you commonly see at the relatively affordable end of the plasma TV market. There's nothing so severe that it provides a regular distraction from what you're watching.
The Samsung PS51E490's ability to reproduce colours well during dark scenes is a function of another respectable part of this cheap plasma's performance: contrast. Because as well as some reasonably pure bright whites and punchy colours, the TV can produce a deeper black colour than is common at its price level.
To put this in its proper perspective, there is undoubtedly a greyer look to dark parts of the picture than you get with Samsung's Real Black Pro TVs or, especially, Panasonic's plasmas - at least those from the UT50 level and higher.
But this greyness isn't severe enough to make dark scenes hard to get immersed in. It also doesn't heavily infuse the subdued colours generally on show in dark scenes, and nor does it tend to obscure much of the shadow detailing that's so important to making dark scenes look credible.
The Samsung PS51E490's impressive HD performance is joined by a better-than-expected 3D effort. Particularly welcome is how little crosstalk pictures suffer with. Some previous very cheap 3D plasmas have suffered excessively with this double ghosting phenomenon, yet while it's certainly not completely absent from the Samsung PS51E490's 3D images, it's neither common nor aggressive enough in its appearance to spoil your 3D experience.
The Samsung PS51E490 also retains a bit more colour vibrancy and brightness than many other 3D plasma TVs we've seen, and while, as noted earlier, there is a bit of judder, in general motion is handled at least well enough not to make it a frequent distraction. There's a nice sense of depth too, and flicker from the active shutter glasses doesn't feel too obvious or fatiguing unless you're watching in a bright room.
Colours look a touch cartoony in 3D mode and there doesn't seem to be as much detail and sharpness when watching 3D Blu-rays as you tend to get with the best active 3D TVs. But 3D pictures are never less than very enjoyable to watch.
Inevitably, though, given its price, there are a few significant issues with the Samsung PS51E490's pictures beyond the relatively minor ones already touched on. The worst is that its upscaling processing isn't very special at all, leaving standard definition pictures looking rather rough and ready; soft, noisy, and not as natural where colour tones are concerned as the set's HD pictures.
There's also a bit of general green dotting noise on show in very dark parts of the picture - especially in 3D mode, when the panel is having to work especially hard. This isn't very obvious from a sensible viewing distance, though, and is reduced considerably if you set the Cell Light feature lower than its 12 level.
Finally in the negative department, the TV tends to infuse its pictures with a little touch of green bias that no amount of tinkering with the available colour and white balance tweaks can wholly remove. But this is something you find yourself acclimatising to over time.
The Samsung PS51E490 overall deserves to have us finish on some highs where its pictures are concerned. So let's wrap up by saying that its pictures largely avoid the fizzing noise problems over skin tones often seen with plasma. Also, it can be watched from a much wider viewing angle than any LCD screen, and it suffers only 30-35ms of input lag, which is low enough to make it a very respectable option as a gaming monitor.