Basic picture resizing feature is available in most image manipulation utilities, apart from the ordinary image resizing there exist an smart resize feature in which intelligent image processing algorithms resizes the image with minimal impact to main content.
Free windows utility Image Resize Guide Lite offers an easy to use solution to this traditional image resizing where all objects are equally reduced which results in difficulty to recognize people and objects in the photo. The utilty offers users an smarter option which keeps focus on the subject utilizing it's "smart" picture resizing algorithm. This results in smaller, resized photos with just unnecessary portions removed.
There are many other interesting image manipulation freewares listed at the developers webpage linked below, do give them a try.