What are “megapixels”?
“Megapixels” applies only to PC (USB) cameras. It’s a measure of how many dots the picture you see is made up of, and the bigger the number, the better. However, like most things technical, there is a catch. Most USB cameras have two numbers – the real pixels and the “interpolated” pixels. Interpolation works like this: I look closely at a small square piece of my picture made up of (say) four adjacent dots in my picture. If all those four dots are green, I could replace them with sixteen dots, and colour them all green. I won’t have changed my picture at all, but I will have increased how many dots there are in it – its resolution. Now If I look at my four dots and three are green and one is pink, I can replace them with sixteen dots and make a guess about where the change from pink to green should come. That guesswork is very clever, and takes a look at what is moving in my picture as well – it’s the same basic technology that helps to cram a whole movie onto a DVD. So I can increase
