Q&A: What Are Effective Megapixels?
I am interested in getting an 8-megapixel camera. Some of the technical descriptions of the cameras I am considering say they are "8 effective megapixels." What are "effective megapixels?" Does that mean the camera actually has a 6 or 7 megapixel CCD and uses firmware to enhance the image up to 8 megapixels?
--Carl Mahan, Georgetown, Kentucky
Think of effective megapixel as an honest appraisal of the camera's resolution after the useless pixels on the image sensor are discounted. Here's the deal: A camera's CCD may have 8.5 million pixels on it, but some of them are on the edges and don't contribute to the picture. So the camera might be advertised as "8.5 megapixel, 8 effective megapixel." The second number is the one you care about.