Resolution
The resolution determines how detailed a scan is. The resolution is normally defined as the number of dots scanned per inch. The units of resolution are dots per inch. You can also think of it as the density of pixels in the image.
The greater the resolution, the greater the image detail you can scan. However, the more detail you have, the greater the amount of data a scan produces. For example, doubling the resolution in both the horizontal and vertical directions results in four times the amount of data.
Each output device also has its own specific resolution. If you scan an image at the same resolution as your output device, the final image will be the same size as the original. Likewise, if you scan an image at double the resolution of your output device, the final image will be twice the size of the original.
Note:
Some software may adjust images that include resolution information so they appear as their actual size.
Overview