# Working with images, cels, and animations

This section gives some additional advice on working with the different 3DO graphics types, specifically the following:

- Working with images
- Working with cels
- Working with 3DO animations

## Working with images

When working with 3DO images, keep in mind the following:

- Images have to fit the TV screen (320 x 240 for NTSC, 384 x 288 for PAL); they can't be scaled by the program.

- Images are saved with 16-bit resolution. The ppmto3DO MPW tool lets you create 24-bit images.

- If you convert 24-bit source art to a 16-bit image, you may get a banding effect if the colors in the image are in the same range. In that case, you can use the 3DO Image Writer plug-in to compute a custom color table that's a gradient to avoid banding.

### Tools for creating 3DO images

Use the following tools in the 3DO Toolkit to create images:

- 3DO Animator (tm) -When you create a 16-bit uncoded cel in 3DO Animator, you can use the resulting graphic as a 3DO image. It is your responsibility to resize the art. This is best done during loading, as discussed in the 3DO Animator User's Guide.

- 3DO Image Writer and PAL Image Writer-Use the 3DO Image Writer and PAL Image Writer plug-ins to create images or images with a custom color table. You have to resize the art before you can create the image. If the art is too large, it is cropped on the NTSC screen. If the art is too small, it is displayed in the upper left corner.

- 3DO PostPro-Use 3DO PostPro to load images and cels and to edit them. You can preview images and multiple cels on the Macintosh monitor and the TV screen.

- ppmto3DO-Use the ppmto3DO MPW tool for converting source art in ppm (portable pixmap) format to 3DO image format.

## Working with cels

This section provides some additional information to get you started. It discusses:

- Selecting a cel type
- Creating and displaying anti-aliased cels
- Packed and unpacked cels

### Selecting a cel type

When you save source art as a 3DO cel, there is a trade-off between how many colors are available (and how much control you have over them) and how small the cel is. The table below gives an overview of all cel types.

    Table 1:  Characteristics of different cel types.
    --------------------------------------------------------
    Cel type/Colors   |Discussion
    --------------------------------------------------------
    16-bit            |The best choice if the source art
    uncoded32,000     |uses a large number of different
    colors(RGB 5-5-5) |colors, though you'll end up with a
                      |cel that uses the largest amount of
                      |space. Supports per-pixel P-Mode; use
                      |a mask for special effects regions.
    --------------------------------------------------------
     8-bit uncoded256 |Can be used successfully for source
    colors(RGB 3-3-2) |art with relatively few colors but
                      |may be unsatisfactory because you
                      |have no control over the palette.
    --------------------------------------------------------
    16-bit coded 32   |Is rarely used since it offers little
    colors (RGB 3-3-3)|control over the colors but uses a
                      |lot of disk space.
    --------------------------------------------------------
    8-bit coded32 base|Provides good visual quality and are
    colors +7 shades  |quite small. A special tool, the
    per color         |Coded-8 CelWriter, lets you create
                      |8-bit coded cels. You can apply
                      |custom palettes created with 3DO
                      |Animator.
    --------------------------------------------------------
    6-bit coded32     |Good choice if your source art has
    colors            |relatively few colors. Supports
                      |per-pixel P-Mode; use a mask for
                      |special effects regions.
    --------------------------------------------------------
    4-bit coded16     |Good choice if source art has 16 or
    colors            |fewer colors.
    --------------------------------------------------------
    2-bit coded4      |Good choice if source art has 4 or
    colors            |fewer colors.
    --------------------------------------------------------
    1-bit coded2      |Good choice if source art has 2 or
    colors            |fewer colors.
    --------------------------------------------------------

Note: If the source art has more colors than the cel, the colors needs to be reduced. 3DO Animator does this automatically; if you use custom plug-ins, you are responsible for color reduction. For more information, see the individual manuals.

### Creating and displaying anti-aliased cels

Anti-aliasing smooths out the rough edges (jaggies) of a computer generated image. The Anti-Alias CelWriter makes it possible to get this effect on the 3DO Station. When you export source art using Anti-Alias CelWriter, it saves a file containing two cels: a source cel and a mask cel. The mask cel is partly translucent, mixing background pixels with source cel pixels to smooth the edges around a cel.

The program that displays the anti-aliased cel has to render the mask cel first, then display the source cel.

### Packed and unpacked cels

Packed cels compress pixels of the same color. In almost all cases, they result in a much smaller cel. They are especially useful if you are using an irregularly shaped (not rectangular) cel. How you create a packed cel depends on the tool you use:

- 3DO Animator-From the 3DO Options menu, use CCB Flags and check the Packed box.

- 3DO CelWriter and 3DO Coded-8 CelWriter-While exporting the cel, click the Set Cel Flags button and make sure Save Cel as Packed box is checked.

- 3DO PostPro-Specify that you intend to create a packed cel when opening it.

## Working with 3DO animations

A 3DO animation consists of a series of 3DO cels. The actual file containing the animation also has information about the frame rate. The file may also contain a preamble, which specifies information the cels share. In most cases, frame rate and preamble information are set by the program. While 3DO animation is in many ways similar to traditional film animation, it differs in several ways:

- In traditional film animation, the animator times a scene on the basis of a projection rate of 24 frames per second (fps). The standard NTSC display allows a projection rate of 30 fps, though lower rates are possible and used frequently.

- A trade-off is necessary between cel size, cel resolution, and frame rate. The 3DO hardware can't play back a large animation at a high resolution using a high frame rate. You can, however, usually get a good compromise if you experiment early on. The graphic artist and the programmer have to work together to find out what combination of cel size, cel resolution, and frame rate works best for which animation.

- The 3DO hardware can shape, move, and stretch each cel or individual cels in an animation.

- Special effects are possible for one cel or all cels in an animation.