One of the arguments from manufacturers in the great megapixel wars is that to get a larger-than-life print, you need a ton of sensor resolution. While it’s true that the pixel count of the sensor largely will determine the acceptable image and print size, it’s not true that the more pixels you have, the bigger and better prints you’ll get. The quality of an enlarged print is largely subjective, and it’s important to point out that there are a number of factors determining optimum print quality. Remember, when you print big, everything is magnified, so there’s no hiding behind compressed details.
All that aside, more megapixels, as most photographers know, doesn’t actually mean an image with higher resolution. While resolution has come to be accepted generally as a term for the active pixel count on a sensor, too many photodiodes actually can be a bad thing when squashed onto a sensor just to boost a megapixel count for promotional purposes. Smaller light-sensitive areas can mean photodiodes that collect less information, as well as increased gaps in between the photodiodes for increased loss of light.
Myth: The larger the print, the bigger the sensor resolution needed
Secondly more megapixels doesn’t always equal a bigger and better print. It’s possible to achieve a better image through know-how, and a good, clean image, even one taken at a smaller resolution, always trumps a low-quality image taken at a higher resolution.
This isn’t to say that a 6-megapixel point-and-shoot will provide you with better or even the same results as a pro level D-SLR. There’s an acceptable maximum to every file size. (The graph provides a good estimation of file size capabilities.)