MACROMEDIA FreeHand MX, Руководство пользователя

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Saving and Exporting Files 353
Working with alpha channels
Using alpha channels, you can export bitmap images with complex masking and transparency for
use in web page graphics, multimedia, video images, and image-editing applications. An alpha
channel is a graphic layer that displays transparent areas, opaque areas, and the outline or edge
of an object.
An alpha channel masks, or outlines, all objects on a page, and reveals a background graphic
through an image. FreeHand can export an alpha channel in the BMP, PNG, Targa, and
TIFF formats.
Note: If you import a bitmap image with an alpha channel, FreeHand displays the image’s transparency onscreen
but does not maintain upon export the true alpha channel that was saved with the original image. For more
information about imported bitmap graphics, see “Working with bitmap images in FreeHand” on page 318. To
export the bitmap image with an alpha channel, you must apply an alpha channel in FreeHand before exporting
the image.
GIF images can also be exported with transparency, but they don’t truly contain an alpha channel.
For more information, see “Exporting to GIF format” on page 355.
When the image is opened in an application that supports alpha channels, the edges of objects in
the image can be easily defined.
Original (left) and exported alpha channel (right)
Note: When FreeHand exports a file, it does not preserve the transparency of objects that have effects applied.
To include an alpha channel for transparency:
1
Select File > Export.
2
Select the TIFF, Targa, PNG, or BMP bitmap file type, and click Setup.
3
Select Include Alpha Channel to create an alpha channel automatically on export.
4
If you want to use a background layer as the alpha channel, select Alpha Includes Background.
For more information, see “Defining transparency using a background layer” on page 354.