Information Technology Reference
In-Depth Information
Figure.6 6
Photoshop Elements, a simpler version of the popular Adobe Photoshop, can be used to create and edit raster graphics.
Depending on the file format, compression can either be lossless (no loss
of image quality) or lossy (some loss of image quality).
The other major problem with raster graphics is that they tend to lose
their quality when resized—especially when enlarged beyond their origi-
nal dimensions. This happens because when you enlarge a raster image,
the pixels don't change size, so the software must simulate a particular
pixel's color, taking up more space than it originally did. The trouble is,
it's not nearly as simple as just adding another pixel of the same color
next to the original, because resizing is often done in odd multiples, like
15%. Therefore, the image-editing software must do its best to simulate
the enlargement by doubling some pixels but not others, and the result is
a jagged or fuzzy image. In Figure 6.7, for example, see how this image,
originally with crisp lines, becomes
pixilated
(that is, you can see the jag-
ged edges of individual pixels) when it's enlarged.
pixilated
The effect of seeing the jagged edges
of individual pixels that occurs when a raster
image is enlarged.
