Understand Color Depth in After Effect

Color depth is the number of bits per channel (bpc) used to represent the color of a pixel. Channels contain color
information: RGB images have channels for red, green, and blue. The more bits per channel, the more colors can be
represented.
In After Effects, you can work in 8-bpc, 16-bpc or 32-bpc color mode for each project.
Even if your output is 8-bpc (Millions Of Colors), you can obtain better rendering quality by having the project (or
render) color depth set at 16-bpc or 32-bpc because of the added precision achieved by calculating color values at
higher bit depths.

32 - bpc

8 - bpc

After Effects assumes that all HDR footage represents color linearly in linear light.When you import HDR images, After Effects converts floating-point 32-bit values from linear light to the project’s working color space.
16-bpc color mode 16-bpc frames require half the memory of 32-bpc frames and offer advantages in terms of speed and storage. Use 16-bpc mode when you work with high-resolution images that contain a narrow range of colors, such as when you’re creating subtle gradients for film effects or HDTV output. Transitions between
colors are smoother with less visible banding, and more detail is preserved than with 8-bpc color (though less than with 32-bpc color). You can import 16-bpc images, including those from Adobe Photoshop, and composite and color-correct footage in 16-bpc mode. Take advantage of 16-bpc color when performing most After Effects tasks, including layer adjustment, frame blending, 3D compositing, and Cineon file import. The Info panel displays 16-bpc color values with exact precision.

When rendering to output module depths of Trillions Of Colors, set the project to 16-bpc color depth to take
advantage of the output file’s extra color precision.
The step is

Choose File > Project Settings, and choose a color depth from the Color Depth menu.

In the Project panel, Alt-click the Project Color Depth button.

Project Color Depth button in the Project panel 32-bpc projects and effects Create 32-bpc projects in After Effects to work with HDR footage, or to work with over-range values - values above one (white) that aren’t supported in 8- or 16-bpc mode. Over-range values preserve the details in shadows and the intensity of highlights.

Because HDR extends dynamic range into shadows as well as highlights, you can bring detail out of dark areas as well as light areas. Blending operations give more photographic results if linear blending is enabled (see “To enable linear blending” on page 66). You can create lights in 3D space or apply one of the 32-bpc blur effects, such as Fast Blur, Gaussian Blur, Channel Blur, Directional Blur, and Box Blur, to HDR footage. You can also apply blending modes to create interesting interactions between layers.
You can use the HDR Compander effect to compress the dynamic range of HDR footage. In this way, you can use tools that don’t support HDR, such as 8-bpc and 16-bit effects.When you’re done, use the HDR Compander to undo the dynamic range compression. The HDR Highlight Compression effect lets you compress the highlight values in an HDR image so that they fall within the value range of a low dynamic range image.
To expand the range of luma levels Some file format modules convert 8-bpc luma from certain hardware, such as cameras, to RGB levels within the range of 16 to 235. In 8-bpcmode,After Effects works with RGB levels from 0 to 255. If blacks or whites appear either crushed or faded, there may be a luma range mismatch that you can correct by expanding the range of luma levels.
You can expand the range of the luma levels to 0 to 255without having to apply a Levels effect. Luma expansion also
works with 16-bpc footage and projects.

Note:

In 32-bpc projects, After Effects can generate over-range values that let you work with whiter-than-white, or overbright
values.

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