Use a gradient mask in Photoshop to help blend one image into another. The depth and opacity of the blending may be adjusted as well as the blending mode of the layer.
This feature works the same in all recent versions of Adobe Photoshop: CS5, CS6, and Creative Cloud (CC).
Tracy has been a senior graphic designer/programmer, instructor, and consultant since 1993 and has developed hundreds of logos, marketing materials, websites, and multimedia solutions for customers worldwide, including involvement in large corporate software rollouts. She has helped many organizations optimize and streamline data solutions. She teaches both onsite and online courses and has her CTT (Certified Technical Trainer) certification. Tracy specializes in teaching graphics, desktop publishing, web design, reporting/productivity applications, as well as the creation of online courses with software from leading vendors.