To change image size in Photoshop, you can use an interpolation method such as Bicubic Smoother or Bicubic Sharper for resampling the pixels. Resized images often lose image quality, most noticeably when enlarged. They can display a stair step or halo around some edges, often referred to as fringe artifacts.
Alien Skin Blow Up 2 is a plug-in for enlarging images to extreme print sizes. The plug-in uses an interpolation method which increases the size of the image while maintaining smooth, sharp edges. You can enlarge 8, 16, or 32 bit images in almost any color space, including CMYK, Lab and Duotone, making this plug-in perfect for both amateur and professional photographers as well as graphic designers. You can automatically create a duplicate of the image before resizing and even control the amount of photo grain that appears in the enlarged image. Blow Up 2 includes over 100 presets for preparing photos for print, saving you time and numerous calculations of the dpi and aspect ratio involved in resizing images for print.