Do megapixels really count?

David Pogue has been having a swipe at megapixel mania, in an article called Breaking the Myth of Megapixels in the New York Times. Beyond about 5MP, picture quality does not get much better and you get all sorts of other problems, Pogue rightly points out. He even does a couple of tests showing that the average person in the street can't distinguish between pictures taken at 7MP, 10MP and a massive 16.7MP. The method used to take the images is open to criticism but he makes a valid point.
So I thought I would take a little test of my own to see what difference pixel count makes on mobile phones.
I took the Nokia N73 that I have on trial, and assembled a little still life (quite Baroque, I think). Then I took three shots, moving out each time and using the digital zoom to frame the same shot. The digital zoom does not actually zoom at all - all it does is select the middle of the image and blow it up to fit the screen, so the resolution effectively goes down by several notches. Unfortunately, I can't tell exactly how much from the manual.The first image is really quite good. Lots of detail and nice colour, considering it was taken by the light of the dining room and the phone's flash. Cameraphones still suffer badly in low light:The second is visibly not as good but still acceptable if you are partially sighted:
The third is what professional photographers call complete pants (but still better than any VGA crapcam:
One of the things about digital images is that you can instantly blow them up to any magnification to examine every little flaw. So I printed all the images out on 6x4 photo paper. Interestingly, the full resolution image was only a bit better than the one taken with the digital zoom at the halfway point. The full digital zoom image was still pants. As ever, the quality depends on the medium to a great degree.
Clearly, cameraphones have some way to go before 'megapixels don't matter'. Cameraphones also have a harder job than 'proper' digital cameras because the lenses are so much smaller and optical zooms are rare.
The advice at the moment has to be never to use the digital zoom unless you want to send the image directly from the phone to your blog or a friend. If you are going to download the picture to a PC, take it at full resolution and edit the image on the PC.