Videonics PowerScript PS4000S, Инструкция по эксплуатации

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Videonics PowerScript Transparency
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Bit-mapped graphics work differently. When PowerScript stretches a bit-mapped graphic
some degradation might occur because the pixels no longer align correctly. In many
cases, this is not noticeable. However, if image proportions are critical, design bit-mapped
images to be 10% wider than normal. When you place the image on a PowerScript page,
select the object, open the
MODIFY menu (see “Changing Object Orientation” on
page 74), then change the horizontal scale factor from 110% to 100% for an NTSC sys-
tem.
Transparency
Bit-mapped images normally occupy a rectangle on the screen, and the rectangle has its
own background color. The rectangle can obscure any object or objects behind it. Object-
based (or, vector) graphics can be made to have a transparent background so that when
superimposed atop other objects, the objects behind can show through.
If you want to create a non-rectangular bit-mapped image, you can use either of the fol-
lowing methods:
• Use a clipping path in an EPS graphic. A clipping path is a shape that cuts away the
background so just the inside of the path is drawn and rest of the area is transpar-
ent. Adobe Photoshop and similar bit-mapped graphic applications can create
paths and place them in EPS files.
• Define an Alpha (transparency) mask and encode it in an APS graphic using a for-
mat called CMYA (as explained in the following section).
Note
The GIF file format has a transparency option available, but it is not supported by
PowerScript.
Bit-Mapped Image Object-Based Graphic
The two stars are a bit-mapped image, so
they have a rectangular background with
its own color (white, in this case). The
while fill of the background rectangle
obscures the bands that lie on a layer
behind (or, below) the bit map. The two stars are object-based graphics
with a transparent background. The
bands that lie on the layer behind (or,
below) the objects can be seen through
the transparent background.