Today's digital cameras have already reached impressive pixel counts. The figures seem sufficient to generate high-resolution images, and even to withstand scrutiny in enlarged prints. A plausible case is often made that the mega-pixel wars are meaningless because digital cameras already have enough pixels.
The claim gains further support from an understanding that resolution is not determined by pixel count alone. In a photograph, resolution also depends on interactions among many other factors, including lens characteristics, low-pass filter response, noise reduction, and processing of contrast and sharpness parameters. By itself, elevating the pixel count doesn't necessarily lead to an appreciable improvement in picture quality.
Consider the 14MP direct image sensor used in the Sigma SD15 and Sigma DP1/DP2. Despite having a nominal 4.6 million figure for the number of pixel locations, this sensor produces images that are widely recognized as having excellent resolution.