Pixels and Photoshop Elements 10 Images
Files you open in Elements are composed of millions of tiny, square pixels. Each pixel has one, and only one, color value. The arrangement of the pixels of different shades and colors creates an illusion to your eyes when you’re viewing an image onscreen.
For example, you may have black and white pixels arranged in an order that creates the impression that you’re looking at something gray — not at tiny black and white squares.
Just about everything you do in Elements has to do with changing pixels. You surround them with selection tools to select what appear to be objects in your image; you make pixels darker or lighter to change contrast and brightness; you change shades and tints of pixels for color correction; and you perform a variety of other editing tasks.
Here's another term to throw at you when talking about pixels and Elements files: Your pictures are raster images. When you have pixels, you have raster data. If you open a file in Elements that isn’t made of pixels, Elements rasterizes the data. In other words, Elements converts other data to pixels if the document wasn’t originally composed of pixels.
You can also have vector content in an Elements file. Text added with the Type tool, for example, is a vector object. When you save an Elements file with the Text layer intact or save it as a Photoshop PDF file, the vector data is retained.
To use most of the tools and commands in Elements, you must be working on a raster image file. If your data isn’t rasterized, many tools and commands are unavailable.