Printed images are cropped or have white borders
A printed image may not appear as expected when the aspect ratio* of the image differs from the aspect ratio of the paper used for printing. This is
most notable when performing borderless printing. If the Aspect Ratio of the image to be printed does not match the aspect ratio of the paper, some of the original image will be cropped or white borders will appear. For example, printing a square (1:1 aspect ratio) image on 4" x 6" (2:3 aspect ratio) paper requires you to manually crop the image to match the ratio of the paper or use a program to automatically crop the image. In either case, some of the original image will not be printed in the full 4" x 6" . If you do not crop the image, white borders will appear in the printout.
Example 1: Original Image from a photo sharing site that uses Square (1:1 aspect ratio) images is printed on 4" x 6" paper without cropping
Note that the printed result has the whole image printed but there are white borders
Example 2: Original Image from a photo sharing site that uses Square (1:1 aspect ratio) images is first cropped then printed on 4" x 6" paper
Note that the printed image fills the paper but not all of the image is printed because of the difference in Aspect Ratios. Crop the image to your preferences in the same aspect ratio as the paper you will be printing on.
*Aspect Ratio is the mathematical relationship of the image width to height. For example, the aspect ratio of a 6" x 4" image would be 3:2, a square image would have an aspect ratio of 1:1 and so on.