Datasheet

When you work in a program such as Photoshop, you are editing the pixels of an image
directly by adjusting existing settings such as color, size, and position for all or part of an
image. In this manner, you can bring a scanned photo or a digital picture of your house
into Photoshop and paint one wall red just to see how it would look before you buy paint
at the store.
Essentially, a raster or bitmap image is a mosaic of pixels, each pixel corresponding to a
mosaic tile. The resolution—fineness of detail—of an image is defined by the number of
pixels per inch (or other unit of measure) in the horizontal and vertical directions. Because
raster images are based on a fixed grid, these images do not scale larger very well. The closer
you zoom into a raster image (or the larger a raster image is scaled), the larger the pixels
seem, which makes the zoomed or enlarged image blocky, or pixelated. To use larger raster
images, you need to start with a higher resolution when the image is created. The higher
the resolution, the larger the file size will be. Figure 1.3 shows what happens when you
blow up a raster image.
Figure 1.3
A raster image does
not scale up very
well. Here is the
front of a stereo
receiver that has
been blown up by
several hundred per-
cent. The pixels look
blocky.
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