High-definition desktop backgrounds do take a lot of disk space, and can range from eight to 16 megabytes in file size, notes Scirra.com. This means that a four-gigabyte flash drive can hold up to 500 images of the same size.
There are different levels of HD images, all of which impact how much memory is used by hard drive or other storage. The higher the pixel density, the more space an image requires for storage. Sharper images, such as those that use 2048 pixels by 2048 pixels, can double the size of required memory to 16MB.
Smaller images, such as those in the eight- to 10-MP range, still provide clear images without the requirement of a lot of memory.