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684 Chapter 20: Managing Scenes and Projects
Pre-Multiplied A lpha—
When on, pre-multiplies the
alpha channel. Pre-multiplying saves computation
time if you later use this image in comp os iting. See
Premultiplied A lpha (page 3–1091) .
Additional Information group
Author N ame, Job Na me/ID, Comments—These
fields are available for y ou to add information
about the file.
Note: To control whether or not the renderer
uses the environment map’s alpha channel in
creating the alpha for the rendered image, choose
Customize > Preferences > Rendering, and
then turn on Use Env ironment Alpha in the
Background Antialiasing group.
If Use Environment Alpha is turned off (the
default) the background receives an alpha of 0
(completely transparent). If Use Environment
Alpha is turned on, the alpha of the resulting image
is a combination of the scene and background
image’salpha.Also,whenwritingTGAfileswith
Pre-Multiplied Alpha set to off, turning on Use
Environment Alpha prevents incorrect results.
Note that only background images with alpha
channels or black backgrounds are supported
when compositing in other programs such as
Photoshop.
TIFF Files
TIFF (Tagged Image File Format) is a
multiplatform
bitmap (page 3–1011) format
originating on the Macintosh® and in
desktop-publishing applications. TIFF is a
common choice if you plan to send your output
toaprintservicebureauorimporttheimageinto
apage-layoutprogram.
There are several classes of TIFF files, each varying
in the color depth and color palette that they
support.
Yo u c a n r e n d e r T I F F f i l e s w i t h a l p h a ,
luminance
(page 3–1058)
,andUVcolorcoordinate
information, which describes
illuminance (page
3–1049)
.Youalsohavetheoptiontorendera
compressed image. Luminance and illuminance
data are rendered by the
Lighting Data Exporter
utility (page 3–299)
.
Interfa ce
ToopentheTIFImageControldialog,clickSave
or Setup on the
Render Output File dia log (page
3–8)
.
When you render to a TIFF file, you have the
following options:
Monochrome—Creates an 8-bit grayscale image.
Co lor—Creates a 24-bit colo r image (no alpha
channel).
ImageTypegroup
Lets you select which image information to save.
8-bit Gr eysca le—Creates an 8-bit grayscale image.
8-bit Color—Creates an 8-bit color image.
16-bit Color—Creates an 16-bit color image.