Adobe Photoshop  is the industry standard for raster-based image tampering. Logo design, typography and other finer work is generally done in vector-based programs like Adobe Illustrator, whereas Photoshop is (as the name insists) the king of photo work. Sometimes this can mean retouching your happy snaps to make them look professional. Other times it could mean seamlessly compositing bits from a bunch of different images into an all new collage image. Honestly, a decent Photoshop user with enough time can fix any blemish, bend any unpleasant reality or graft any weird thing onto your shoulders they want. Its digital magic.