TGA
Developed by
Truevision, Inc.,
Targa, aka
TGA, is a
bitmapped graphics format, usually uncompressed, that supports an
alpha channel.
Second Life can import both 24-
bit (no alpha) and 32-bit (alpha)
TGA files. This format is the graphical workhorse of the
SL garment industry.
Avoid using the 32-bit format if the texture doesn't have/need any
transparency; otherwise there might be unwanted visual effects.
Note that SL doesn't use
TGA files, but actually
JPEG2000.
TGA files are converted to JPEG2000 and uploaded in JPEG2000 format to the
asset server.
Texture data is downloaded as JPEG2000 and decompressed directly into
memory on the
client.
Wikipedia: TGA
texture