Bitmap Export Dialog Box - Bitmap Options tab
Transparency
This button duplicates Transparent background on the Palette Options tab. It provides compatibility for CorelXARA users.
With transparency enabled, the bitmap is 'transparent' in all areas not covered by a selected object. This makes it easy to remove the white background from exported pictures and makes them ideal for publication on the Internet (see Internet Bitmaps Overview).
If the Quality setting is high (anti-aliasing is turned on) the edges of the drawing will be anti-aliased with whatever is behind it (as normal). Normally the anti-aliasing is to the paper color of white.
When transparency is enabled, the selected items are used to determine what is going to be transparent in the GIF, but all objects are rendered. This makes it simple to create bitmaps which anti-alias to the background they will eventually be on, by placing that background behind the drawing. Then when the bitmap is exported ensure that the background is not selected but the drawing is and that the selection option is used.
Note that if you create a transparent GIF file, one of the palette colors is used as the transparency. This means (for example) that a 2 color GIF contains one color and transparency.
Note that GIF transparency has a different meaning to the transparency in the Transparency Tool. This process does not take into account any of this type of transparency applied to objects in the document.
Interlacing
Select this option if you want an interlaced bitmap.