Simply put, any image taken from a scanner, computer, or digital camera is a digital image. A digital camera can create this image using what is known as a CCD chip, located behind the camera lens, and composed of many small light sensitive cells that have been arranged to divide the picture into rows and columns of smaller sub areas.
Scanners function nearly the same way, containing one row of light sensitive cells, and a motor to move the row down the page, creating columns that form an image grid.
In both cases, both the color and brightness of each area are sampled, which means that the color value of each is measured and recorded as a numeric value representing each color, a process known as digitizing the image.
These numeric color data values are known as pixels, word that is based on the computer related term: PICture Element. Digital images, then, essentially are composed entirely of, and dimensioned in, pixels.
The size of an image, measures in pixels, determines how this image can be used, and there are two main uses for images: printing it, and showing it on a video screen.
If an image is to be shown on a video screen, it is important to make sure that the size of the image is consistent with the size of the screen, which is not difficult, since video screen size is measured in pixels, and the number of inches is a negligible factor when sizing.
In terms of printing images, paper is measured in inches, which is why the printing resolution of an image is always specified in pixels per inch, or ppi, for spacing purposes. The image size, measured in pixels, determines the size of the image to be printed, based on the inch length of the paper.
There are many advantages of scanning film and slides to produce images. Scanning film and film slides, generally speaking, produces higher quality images than simply scanning prints.
The main reason for this is because scanning the film or slide is, in a sense, using the original image to make a copy, while an already developed print is more of a second generation copy, which will in turn produce a third generation copy once it is scanned.
Film also contains greater detail and contrast, since most film is capable of at least 3,000 dpi, compared to 300 dpi for color photo paper.
A film scanner allows for enough quality image pixels to be scanned, as opposed to a standard type of scanner, and thus can produce more detailed, higher quality images, particularly when it comes to creating larger sized prints.
For more information visit our slide scanning website for more information about photos, scanning, and online albums.