Page 381 - Xara Designer Pro X17

Photo Handling 381

require an object with minimum shading and just broad areas of color. Use one pass for
this.

Alternatively you may require color shading to closely match the bitmap. Use multiple
passes for this.
Remove noise

If you scan a photograph you often scan small specks of dust sticking to the photo's
surface. These produce "noise", or small, unwanted areas of a different color.

Also many bitmaps try to improve the look by "dithering" pixels and this introduces
unwanted noise (especially common for 256 or fewer color bitmaps).

When tracing 256-color bitmaps that are heavily dithered, you should set remove noise to
high (if you zoom into the bitmap in the document, you can see if it is dithered).

This control removes noise and dithering by ignoring very small areas of color.

Minimum area
Areas smaller than the size set in this control are ignored (size is in pixels). Examples are
scanned photographs with a lot of fine detail such as blades of grass.

Initial and final color tolerance
Color tolerance is how great a color change is required before the tracer considers two
areas to be of a different color.
Initial color tolerance is used for the first of multiple passes. It is similar to the broad
brush strokes used to create the underlying colors on a conventional painting.

Final color tolerance is used for the last pass. It is similar to merging the edges of color
transitions to simulate shading.

On multiple passes, the tracer gradually reduces color tolerance from the initial value to
the final value. Thus, initial color tolerance should always be set higher than final color
tolerance. On a single pass, only the final value has any effect.
Accuracy
This controls how accurately the tracer follows the outlines of the original bitmap. The
more accurately it traces the outlines, the more control handles are required on each
shape and hence the more memory is required for the final object.

This option has no effect on corners, only on smooth curves.

Smoothing
This controls how accurately corners (sharp changes of direction) are traced. Increasing
the smoothing takes longer to trace the image but can reduce the final file size.