A typical TV, Computer or any other screen is made of of many dots. A typical computer screen has 1024 dots across and 768 down so this produces a massive matrix of about 787000 dots or pixels. A TV screen is less at around 800x600 and a digital camera considerably more with many at 3million pixels. A printer quotes this in DPI or dots per inch, if you have a printer that can print 1024dpi a camera with a resolution of 1024x768 would be able to fit all the information into 1 inch across (and a bit less down), any bigger than that and it has to start adding extra information which after a bit is detectable in the form of being 'grainy' or noticable jagged edges.