CHAPTER 4
204
Graphics
projected into an annotation’s target coordinate system (see Section 9.5.1, “3D
Relationships among Coordinate Spaces
Each arrow in the figure represents a transformation from one coordinate space
to another. PDF allows modifications to many of these transformations.
Because PDF coordinate spaces are defined relative to one another, changes made
to one transformation can affect the appearance of objects defined in several
coordinate spaces. For example, a change in the CTM, which defines the trans-
formation from user space to device space, affects forms, text, images, and pat-
terns, since they are all upstream from user space.
4.2.2 Common Transformations
A
transformation matrix
specifies the relationship between two coordinate spac-
es. By modifying a transformation matrix, objects can be scaled, rotated, translat-
ed, or transformed in other ways.
Form
space
Glyph
space
Text
space
User
space
Image
space
Device
space
Pattern
space
FIGURE 4.4
Relationships among coordinate systems