Take, for instance, the bit where silly Willy (Smith) follows his dog (no, really, he does) into a dark warehouse thingie even though he knows that hiding within are almost certain to be a hive of slavering, rabid mutants. The potential tension of the scene is all but ruined by some horrendous amounts of dot crawl over the picture, and a bizarrely washed out black level that makes the picture look flat and artificial.

And no, before you ask, neither of these faults has anything at all to do with my projector. How do I know? Partly because I've seen my JVC DLA-HD1 perform immaculately with other similarly dark scenes in other Blu-ray movies, and partly because the black bars above and below the 1080p/24 2.4:1 VC1 transfer look much darker and complete free of any kind of noise.

In other words, any noise and black level issues in these dark scenes are all down to Warner’s transfer, fair and square. And as regular readers will know, this sort of dark-scene noise is hardly a rarity among Warner Bros transfers. Sigh.

So obvious are the noise and contrast issues during dark scenes, in fact, that I find it bizarre that other HD review sites don’t appear to have picked up on them. It's almost enough to make you think they haven't really watched the film all the way through...

Once this particularly dark scene has flagged the noise and black level shortcomings up, you also spot them to a lesser extent in various other dark interior scenes in the film.

It's just as well for the I Am Legend Blu-ray, then, that since the film's freaks only come out at night, the majority of the film takes place largely during bright, daylight hours. And at these times the video transfer is impressive, sometimes even outstanding.

Colours, for instance, are perfectly balanced, with the sensationally vivid hues of the red Shelby sports car Smith is driving at the film's start sitting comfortably alongside impeccably natural skin tones and effortless subtleties of shade in the largely grey New York backdrops. Terrific stuff.

It's great to see, too, that the film's bright scenes are largely if not totally free of the noise that can afflict dark scenes. Plus the New York's sunlit skies look really natural and credible, avoiding the tendency to 'wash out' in near-white areas that some Blu-ray transfers suffer with.

Bright scenes also highlight how sharp the transfer can be when it's not snowed under by noise. Our favourite indicator of HD detail, skin pores, are abundantly evident on Smith's face at all times, and on the faces of the other characters during the inevitable flashback sequences.

You can also make out every blade of grass in the various tufts of weeds and Smith's 'vegetable patch'.

The sharpness of the image does have one unfortunate downside, though, in that it doesn't half embarrass the CGI in a few places. Relatively static CGI stuff, such as the shots of a decaying New York, are capable of looking pretty good. But the CGI effects for anything 'living' are frequently left looking distractingly bad.

The lions, for instance, look blurred, unnaturally lit and just completely out of sync with their supposed New York environment, while the mutants look laughably bad for most of the time; more like escapees from some third rate video game than believable foes in a big-budget Hollywood movie. And as I suggested a moment ago, all these failings are simply highlighted by the clarity of the HD transfer.

So ropey does the CGI often look on this Blu-ray, in fact, that I'm almost tempted to commit sacrilege and suggest that I Am Legend might hold up to scrutiny better on DVD than Blu-ray!

One other minor technical issue I have with the transfer is one I also saw on Warners' Blu-ray of Blood Diamond; namely that for a few shots the picture appears slightly out of focus over its top and bottom thirds. Odd.

Figuring out how to put a final score on all this visual chaos is a tough one. How do you rate a picture that frequently looks awesome during bright scenes, but below par during dark ones? And is it fair to blame the HD picture quality for highlighting rank flaws in some of the film's CGI effects? Hmm.

In the end I decided the overall situation lay somewhere between average and good, which to my mind added up to a nice round 15.

English options available include a 640kb Dolby Digital 5.1 mix and, excellently, a Dolby TrueHD mix. People who don't have English as a first language should note that there are also French, German, Italian and Spanish 5.1 mixes for the Theatrical version of the film. However, if you watch the Alternative version (which we'll talk about in the Extra Features section) you only get the two English soundtracks; the foreign language ones vanish into thin air.

Anyway, getting back to the two English mixes, both are consistently excellent, combining huge dynamics during action scenes (I seriously feared for my own foundations when Will Smith detonates the protective ring of explosives around his home, for instance) with some terrifically dynamic use of the rear channel, loads of subtle effects delivered with pin-point accuracy (check out the bit where Smith hits a golf ball seemingly right across your room), a perfectly pitched vocal channel, and a bold use of silence that both captures a sense of the isolation of Smith's life during daylight hours, and emphasises the drama when the soundstage bursts into action.

By the way, if you take all my comments in the previous paragraph as referring to the Dolby Digital 5.1 mix and then imagine the impact of each aspect enhanced by at least an extra 20%, then you'll be getting in the right sort of descriptive area for the wonderfully bonkers Dolby TrueHD mix.

My only bitch about the Blu-ray audio concerns the ridiculous racket the mutants make. Their crazy screaming is totally unimaginative, B-movie nonsense. What's more, the incessant, over-egged screaming also makes the mutants less rather than more scary, since it's way too far removed from any sound a human - even a mutated one - would ever utter.

I should also add at this point that I really didn't like the way the pop-up menus are organised with regard to playing the original theatrical or alternative version cuts of the film. Basically it's far too easy to get confused about which version you've actually selected to watch. In fact, thanks to this problem my first viewing of the film for this review was accidentally of the version with the alternate ending. And if I could make this mistake even with all my AV experience to call on, I'm sure many Joe Publics will make the same mistake too. Unless they’ve just read this, of course.