Adobe Photoshop does a good job of resizing pics without losing too much quality. It is best to scale down (or up) photos by the power of 2 (binary math here). For example, scale down either width or height by a half, a quarter, 1/8, etc... Then either save a copy or save as "JPEG" format using Photoshop. A JPEG Options window should pop up with a slider that allows you to select image quality. Slide the slider all the way to the right (quality 12) if you want the best quality at the expense of file size. A quality settings between 6 and 8 would give good image quality and small file size.