At first glance, these two digital photos seem almost identical. That's because you're viewing them on a computer display.

Computer displayed images are limited to 72 dpi.

This photo was taken by a Megapixel camera which is able to record images that are 1280 x 1024 pixels, for a total of 1,310,720 pixels per image. This means it has more than four times the resolution of a 640 x 480 VGA camera.

This photo was taken with a VGA digital camera, which as recently as early 1998 were the only kind available to the average consumer. They are still available today.

Light enters the camera's aperture where a lens focuses it onto the CCD (Charge-Coupled Device). Much like the film in a photographic camera, the CCD records the image. 

A CCD is a chip whose surface is composed of thousands of light-sensitive electrical sensors. To record the hue of the light, the sensors operate in three's, each one designed to record only red, green or blue light. Since all colors are a mix of these colors, the sensors mix their signals together to identify a single hue. In addition, each sensor is designed to measure the light's intensity, the brighter it is, the higher the electrical charge. All of this is done digitally and by combining the information about the hue and intensity, the camera assigns a set of specific values to each pixel. Each pixel then becomes part of the complete image. 

Megapixel images

Now, thanks to advances in technology, digital cameras can hold more than one million light sensors, providing near picture-perfect images, four times more detailed than the VGA format, and at very reasonable prices. 

Printing photos

Kodak has said it takes at least one million pixels for a digital photograph to match the quality of a 3 x 5 inch print. A megapixel picture can provide an exceptionally good image. By contrast, VGA cameras provide only about 25 to 30% of the resolution. 

Cropping or Zooming in

A megapixel image allows you enough resolution to really zoom in on your subject, giving you much more leeway for cropping, enlarging and otherwise manipulating images. The VGA image does not allow this flexibility. 

Enlarging

The difference really begins to show when you print a 3 x 5 inch sized picture. A VGA image clearly looks like digital image, like a newspaper photograph. The megapixel image is hardly distinguishable from commercially developed and printed photo. Most megapixel photos can be enlarged to 5 x 7 or even 8 x 10 and retain a near photographic quality. 

A VGA camera is of limited use. If you want to combine the power of digital photography with the quality images of conventional photography, a megapixel camera is your best bet.