We should mention aspect ratio too, resampling dialogs always have it.
Aspect ratio is the ratio of the image width to the height.
If we double the width of an image, we should exactly double the height too, otherwise we create a short fat image, or tall skinny image, not in the same proportion as the original. When resampling, you probably always want to keep Aspect Ratio at the original value, to prevent distorting the image. There will be a software button for this, so that if you change one image dimension, the other tracks it automatically and accurately. The Aspect Lock is a very handy feature, don't overlook it. In Microtek ScanWizard, it is the little padlock symbol to the left of the Input dimension window.