Pixel – Picture Element
Smallest element of a digital photograph. A pixel stores the color and brightness at any one recorded point in a digital photo.
This digital photograph is 2 inches wide and 1.5 inches high.
Its resolution is 360 pixels per inch.
The number of pixels in this image is (360 pixels per inch X 2 inches) X (360 pixels per inch X 1.5 inches) = 388,800 pixels or 388.8 kilopixels
This digital photograph is 10 inches wide and 7.5 inches high.
Its resolution is 72 pixels per inch.
The number of pixels in this image is (72 pixels per inch X 10 inches) X (72 pixels per inch X 7.5 inches) = 388,800 pixels or 388.8 kilopixels
Note that both photographs have the same number of pixels!
It is generally accepted that printing high quality digital photographs requires about 300 pixels per inch, though you can probably get by with less.
72 pixels per inch is a standard for displaying photograph on a computer display because this is the finest resolution that most computer displays can show.
Consumer digital cameras can capture between 2,000,000 and 10,000,000 pixels (or 2 to 10 megapixels) per picture.
Because of the way a camera formats a photograph for saving, the the picture may be bigger or smaller than a camera's stated resolution.
Three common formats are JPG, TIF and Raw.
JPG is an international standard and is the most common digital format. It will produce filess smaller than the cameras stated resolution because it compresses data. It very cleverly throws data away to make the photograph smaller but not so much that you notice. In most digital cameras there are JPG options for the amount of compression.
TIF is also an international standard that keeps everything your camera makes. TIF filess are usually bigger than your camera's stated resolution because it carries information about the photograph that other kinds of photographic software can use.
RAW photographs are the exact output that your digital camera produces. The RAW format is different for every brand of camera. To use a RAW photograph you need software from the manufacturer so that you can edit these photographs and convert them to standard JPG or TIF formats.
Note! To make a digital fine art print that is 16 inches by 20 inches at 300 pixels per inch, you will need a digital photograph that contains at least 28,800,000 pixels (or 28.8 megapixels). No digital camera that is by any stretch of a wallet affordable can produce that many pixels. Affordable digital scanners for film, however, can produce resolutions that are much greater, so do not through away that film.
Another way to get a greater number of pixels is through interpolation done by digital photo processing software such as Adobe Photoshop. This software estimates new in-between pixels from the surrounding real pixels that your camera has recorded. This works pretty good but you cannot do it too much or it will began to be apparent.
If all you want to do is make nice 6X4 inch prints for your family, use 300 pixels per inch. This will result in a digital photograph that is:
(6 X 300) X (4 X 300) = 2.16 Megapixels so all you will need is a 3 megapixel camera.