The Targa (TGA) format was developed by Truevision for their video boards. The format supports 32-bit true color; that is, 24-bit color plus an alpha channel, and is typically used as a true color format.
Targa files are widely used to render still images and to render sequences of still images to video tape.
Some Targa files created by other applications have different file-name extensions. 3ds Max can render the .vda, .icb, and .vst variants as well as .tga.
Clicking Render or Setup in the Render Output File dialog displays the Targa Image Control dialog.
When you render to a Targa file, you have the following options:
Creates a separate file for the alpha channel. The file name created for the alpha-channel file starts with a_ and then appends the full file name. For example, if you check this box and render the file greek004.tga, 3ds Max creates the file a_greek004.tga for the alpha channel. (Sometimes the name will be longer than 8 characters.)
When on, pre-multiplies the alpha channel. Pre-multiplying saves computation time if you later use this image in compositing. See Premultiplied Alpha.
These fields are available for you to add information about the file.
Preferences Rendering, and then turn on Use Environment 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's alpha. Also, when writing TGA files with 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.
