Datasheet

11
Working with Digital Images
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Images that are made up of some combination of solid colors, simple gradations between colors,
distinct shapes, and lines can be constructed as vector images. Simple logos and cartoon-type illus-
trations often have these characteristics, but some complex illustrations do, too. While eliminating
the worry about having enough resolution is an advantage, keep in mind that the vector compo-
nents often have to be created or adjusted by hand, so creating vector images can be more time-
consuming than creating bitmap images. Bitmap images can be created by taking a photo with a
digital camera or by scanning an image. Vector images must be hand-drawn using vector tools in
software such as Photoshop or Illustrato. Note that an image that is a good candidate for the vector
format does not necessarily have to be in vector format. It can be a bitmap image.
Since numerous file formats can contain vector information, it is not immediately apparent
whether an image is a vector image or contains vector information. If an image contains vector
information, you can find it in any of four places in the image:
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On a vector layer mask (right-click [Ctrl-click on a Mac] on a layer mask; if you see vec-
tor options, it is a vector mask rather than a standard layer mask).
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On a type layer in the Layers palette. As long as you can still see the T in the layer thumb-
nail, the type is made up of vectors.
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On a path in the Paths palette. All paths in the Paths palette are vectors.
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In a Smart Object layer. Some have vector information embedded. You can double-click
the Smart Object layer to open its linked file and examine it for vector information. The
linked file may be a Photoshop or Illustrator file. (Content in Illustrator files is typically
vector.)
There can be a combination vector and bitmap image. If an image contains bitmap parts, the image
has to have enough resolution to describe the detail in the bitmap parts.
In Figure 1.3, the vector information — the path of the dog — is shown on the vector layer mask.
FIGURE 1.3
A vector-only image in which the active vector information is contained in a vector layer mask