Selecting Image Formats and Render Resolutions
Using the default image format and render resolution is rarely a good choice. To create a professional animation, you should familiarize yourself with compression schemes, image formats, and key differences between video and motion picture technology.
Differentiating Image Formats
Maya Software, Hardware, and Vector Tenderers can output 30 different image formats. You can select the format by switching the Image Format attribute in the Render Settings window. Although any of the formats can be used successfully in the right circumstance, AVI, QuickTime, JPEG, Targa, and TIFF formats are perhaps the most popular. At the same time, Maya IFF, PSD, Adobe Illustrator, EPS, and SWF formats are designed for specialized tasks.
AVI (.avi) and QuickTime (.mov) On Microsoft Windows systems, Windows Media Player AVI movies are an available format. By default, Maya renders AVI files with no compression. However, you can choose other compression schemes by clicking the Compression button that appears just below the Image Format attribute. Although AVIs are convenient for short tests, they are not suitable for most renders. If a batch render fails or is intentionally interrupted, the AVI file is permanently lost. In addition, individual AVI frames cannot be checked as the render progresses. conversely, the QuickTime format is available on systems running Macintosh OS X. QuickTime suffers from the same drawbacks as AVI.
JPEG (.jpg) Stands for Joint Photographic Experts Group and is one of the most popu-| lar image formats in the world. The main weakness of this format is the lossy qual-
z ity of its compression, whereby artifacts appear along edges and other high-contrast
- areas. By default, Maya sets the compression quality of rendered JPEGs to 75 percent.
- See the section "Changing Compression Settings" later in this chapter.) Maya does g not support CMYK variations of the JPEG format.
Targa (.tga) Developed by Truevision in the mid-1980s, this remains a robust and o reliable image format. Targas can store an alpha channel and are readable by the major-
- ity of digital image and compositing programs. Targa file sizes are relatively large,
- which is perhaps their main disadvantage. An average 720 x 540 Targa might take up
- 1.1 megabytes, while the same size JPEG with a 75 percent quality setting will be a
2 mere 60 kilobytes. Not all Targa formats are supported by Maya.
« TIFF (.tif) Stands for Tagged Image File Format and is another popular format
< developed in the mid-1980s. TIFFs can store alpha and are similar in size to Targas.
u The TIFF format has numerous variations and compression schemes, however, and are therefore inconsistently interpreted by various graphics programs. In fact, the mental ray renderer in Maya may return an error when unsupported TIFF variations are encountered as File textures. (Should this happen, convert the image to another format.) By default, Maya TIFFs are compressed with TIFF 6.0 compression. (See "Changing Compression Settings" later in this chapter.)
Maya IFF (.iff) A native format developed by Alias. While Maya's FCheck program reads the IFF format, such digital imaging programs as Adobe Photoshop and Gimp are unable to open them. On the other hand, compositing programs such as Adobe After Effects read IFF files. The IFF format can store specialized data (depth, motion, and vector).
PSD and PSD Layered (.psd) The standard Photoshop image format. If PSD Layered is chosen, the background color is placed on a Photoshop locked background while the objects are placed on a separate layer with transparency surrounding them. In this case, no alpha channel is provided (even if it is checked in the Render Settings window). AI (Adobe Illustrator; .ai) Converts the scene into a series of editable spline paths. The Maya Vector renderer must be used to output this format. AI files can be read by Macromedia Flash authoring programs.
Note: Maya Software, Maya Hardware, Maya Vector, and mental ray renderers are unable to support all 30 image formats. For a detailed list of which renderer supports what format, see the "Supported Image Formats (Rendering)" page in the Maya Help file.
EPS (.eps) Stands for Encapsulated PostScript and can contain both bitmap and vector information. If rendered with Maya Software, a bitmap image is produced. If Maya Vector is used, a vector image is produced. The vector version of the EPS format can be read by Adobe Photoshop, Illustrator, and Acrobat.
Macromedia Flash (.swf) A vector image format. All the frames of a Macromedia Flash render are contained within a single file. You must use the Maya Vector renderer to output this format. g
RLA (.rla) and SGI (.sgi) RLA is a legacy Wavefront image format that can store alpha and Z-depth channels. SGI is a legacy Silicon Graphics image format that supports an alpha channel. R
a to
A Note on 16-Bit Color Space S
The majority of Maya image formats operate in an 8-bit color space (8 bits in red, 8 °
bits in green, and 8 bits in blue, totaling 24 bits, or 16,777,216 possible colors). In the z
realm of consumer electronics, this color space is commonly referred to as True Color. At present, the majority of consumer monitors offer a 32-bit variation of True Color. This is a 24-bit color space with an extra 8 bits set aside as an empty placeholder (necessary for 32-bit architecture) or for alpha information. By comparison, Maya16 IFF, TIFF16, and SGI16 are three available Maya image formats that operate in 16-bit S
color space (16 bits per channel, totaling 281 trillion possible colors).
The human eye is popularly believed to discern 10 million color variations. As such, 16-bit color may seem like extreme overkill. However, many image-processing filters create superior results when operating at a higher bit depth. Hence, programs such as Adobe Photoshop and Adobe After Effects offer the option to work with 16-bit images. Low bit-depth errors are most commonly seen as banding (posteriza-tion), where the color transitions fail to be smooth (see Figure 10.19). Although 8-bit color space is satisfactory for many applications, 16-bit color space is superior for any project in which color and color manipulation is critical.
8-bit color space
16-bit color space
Figure 10.19 (Top) Color banding caused by a Gaussian blur in 8-bit color space. (Bottom) The result of the same blur in 16-bit color space.
o Note: Maya supports several floating-point, 32-bit image formats: OpenEXR, DDS, and HDR. In addi-
o ^fts tion, mental ray is able to produce 32-bit images through its Primary Framebuffer. These image formats are designed for High-Dynamic Range Images (HDRI), which are discussed in detail in Chapter 13.
Post a comment