Broadly speaking, the quality of the image. Working in the printing and image, usually inch resolution (dpi) will be measured at the point - from a dot per inch, the image quality, large-scale needed to increase the file . Is, 800 × 600 most of the famous 1024 x 768 on Windows, the number of pixels, according to the resolution of the desktop - is the original image, if the latter are large and visible icon, means that many of them fit on the screen.