Graphics Programs Reference
In-Depth Information
Optimizing a Copy of the Graphic for Tracing
You need to optimize and massage the original bitmap data
a little to allow the Bitmap Tracer utility to do its best work.
Let's prepare the graphic, the Earth, for a proper auto-trace:
Create a shape that surrounds the globe graphic only.
The quickest way to do this is a single-click technique
with the Pen Tool.
With both objects selected, press
CTRL - 3 (Arrange |
Combine Shapes | Intersect Shapes). There is also a
button on the Arrange Toolbar you can access from
Window | Control Bars.
You need to edit the edge where the ligature of the
in “Globe” intrudes on the globe so the graphic will be
traced as desired. Put a rectangle behind the cropped
bitmap of the same color as the original background.
Use the Eyedropper next to the Color Line to sample
and then apply the original bitmap background color.
The image is now cropped, but the Bitmap Tracer
disregards cropping (crops in Xara aren't permanent). You
need to make a copy of the cropped image to make Bitmap
Tracer evaluate only the pixels that represent the globe;
press CTRL - SHIFT - C to make a bitmap copy of the selection.
In the Create Bitmap options box, choose True Color
from the Color Depth drop-down list on the Palette
Options tab. This step is not mandatory when you're
creating a bitmap copy for tracing, but by default “True
Color+Alpha” is selected, and alpha masking will
cause Bitmap Tracer to produce an extra (unnecessary)
background object.
Click the Bitmap Size tab, and then
type about 280 in the DPI field to
generate a bitmap copy that's about
480 pixels in height. What you
are doing here is up-sampling the
original image. Some loss of image
quality is inevitable, but you're
creating artificially enlarged details
that will help guide the auto-tracing
process, giving it more data (albeit
fake data), and original image quality
is not the goal in this preparation
process. Click Create.
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