I am wondering if anyone knows where the new math comes from when the resolution of the CCD in a digital camera is discussed. A 640 X 480 camera gaives you just that, 640 pixels by 480 pixels. Some how as the numbers go up in image size there is this rounding up that seems to go on. For instance a 2.1 mega pixel camera actually gives you a 1,920,000 pixel image 1600 X 1200). I call this 1.92 not 2.1. Another is the 2.3 or 1800 X 1200 image which calculates out to 2,160,000 or actually the 2.1 that the other camera is advertising. The so-called 2.5 megapixel camera actually is the 2.3. Now with the 3.3 megapixel cameras what will be the real resolution? Is my calculator defective? The newest of these, the Casio QV3000EX and Canon Powershot S20 both advertise 3.3 megapixel camera but the image size is 2048 by 1535 which by my trusty Casio wristwatch calulator comes out to 3,145,728 or 3.1 megapixels. So what is up with this anyway?

-- Bob Darrow (worrad@yahoo.com), February 29, 2000

Answers

Virtually all digicam sensors are larger in pixels than the image size they produce. The extra pixels ar used for such things as comparing noise from non-image areas so that it can be electronically deleted from the image. The total number of pixels are generally called "gross" pixels.

For a good online tutorial concerning digital cameras see Dennis Curtin's tutorial at: http://www.shortcourses.com/

Rodger

-- Rodger Carter (rodger.carter@wpafb.af.mil), February 29, 2000.

The quoted pixel count, as with so many things, is simply the largest number the marketing department can get away with.

-- Alan Gibson (Alan@snibgo.com), February 29, 2000.