Graphics Programs Reference
In-Depth Information
To make this possible to type in manually, we've defined a one-bit-per-pixel black and
white image, containing just 64 bits of data. Typically, images would be hundreds or
thousands of pixels in each direction and with up to 16 bits per component, with one,
three, or four components.
Images always map to the square
(0,0)...(1,1)
in user space, so we use
cm
operators to
scale the image to the appropriate size and position:
q
1 0 0 1 100 100 cm
Translate
200 0 0 200 0 0 cm
Scale
/X2 Do
Invoke image XObject
Q
q
1 0 0 1 400 100 cm
And again with a different position and scale
100 0 0 100 0 0 cm
/X2 Do
Q
The result is shown in
Figure 5-15
.
Figure 5-15. Image XObject used at two scales
