Datasheet
8-Bit Image File Commonly referred to as 24-bit color display or True Color, each color
channel is given 8 bits for a range of 256 shades of each red, green, and blue channel for a
total of 16 million colors in the image. This color depth gives the best color quality for
an image and is widely used in most animation applications. It is said that the human eye
cannot see quite as many shades of color as there are in a True Color image. Most of your
renders from Maya will probably be as 24-bit color files.
16-Bit Image File Used primarily in film work using such file types as Cineon format or
TIFF16, the image file holds 16 bits of information for each color channel, resulting in an
astounding number of color levels and range. Each file can exceed several megabytes even
at low resolutions. These files are primarily used in the professional workplace and are
standard for film work since outputting CG to film can require high levels of color and
brightness range in the image.
COLOR CHANNELS
As mentioned, each image file holds the color information in channels. All color images
have a red, green, and blue color channel. Each channel is a measurement of how much
red, green, or blue there is in areas of the image. A fourth channel, called the alpha chan-
nel, is used as a transparency channel. This channel, also know as the matte channel,
defines which portions of the image are transparent or opaque. Not all image files have
alpha channels. You can read more about alpha channels in Chapter 7.
FILE FORMATS
In addition to image type, several image file formats are available today. The most com-
mon perhaps is JPEG (Joint Photographic Experts Group), which is widely used on the
Internet.
The main difference between file formats is how the image is stored. Some formats
compress the file to reduce file size. However, the greater the compression, the poorer the
image’s color.
The popular formats to render into from Maya are TIFF (Tagged Image File Format),
SGI (Silicon Graphics Inc.), Maya IFF (Maya Image File Format), and Targa. These file
formats maintain a good 24-bit color depth using an 8-bit image file, are either uncom-
pressed or hardly compressed (lossless compression), and are frequently used for broad-
cast or film work. These formats also have an alpha channel, giving you better control
when you later composite images together. To see an animation rendered in a file sequence
of TIFFs, for example, you must play them back using a frame player such as Fcheck or
compile them into a movie file.
Ultimately, your final image format depends on the next step in your project. For example,
if you plan to composite your CG, you’ll need to output a format that can be imported by
your compositing or editing program. TIFF files are perhaps the best format to use as they
are widely compatible, store uncompressed color, and have an alpha channel.
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