If you have tried to enlarge images in Photoshop, you tend to get the "jaggies". When an image is reduced in size, or when the size is naturally small, there are a fixed set of pixels to work with. When you try to enlarge the image, there are no pixels available to fill the additional space and so it gets that pixelated look to it which give the appearance of a bunch of jagged edges; hence, the "jaggies".

Blow Up is the image enlargement plug-in from Alien Skin Software that allows you to resize your image upward as much as four times (1600% area) without jagged artifacts or halos. In some cases it can enlarge up to six times (3600% area) without obvious artifacts.

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