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  "title" : "Color table atom ('ctab')"
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# Color table atom ('ctab')

An atom that defines a list of preferred colors for displaying the movie on devices that support only 256 colors.

## Overview

Color table atoms define a list of preferred colors for displaying the movie on devices that support only 256 colors. The list may contain up to 256 colors. These optional atoms have a type value of `'ctab'`. The color table atom contains a Macintosh color table data structure.

The layout of a color table atom is as follows.

|Data field                                                                                     |Bytes   |
|-----------------------------------------------------------------------------------------------|--------|
|``doc://com.apple.qtff/documentation/quicktime-file-format/Color_table_atom/Size``             |4       |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Color_table_atom/Type``             |4       |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Color_table_atom/Color_table_seed`` |4       |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Color_table_atom/Color_table_flags``|2       |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Color_table_atom/Color_table_size`` |2       |
|``doc://com.apple.qtff/documentation/quicktime-file-format/Color_table_atom/Color_array``      |Variable|

## Topics

### Data fields

[`Size`](/documentation/quicktime-file-format/Color_table_atom/Size)

A 32-bit integer that specifies the number of bytes in this color table atom.

[`Type`](/documentation/quicktime-file-format/Color_table_atom/Type)

A 32-bit integer that identifies the atom type.

[`Color table seed`](/documentation/quicktime-file-format/Color_table_atom/Color_table_seed)

A 32-bit integer.

[`Color table flags`](/documentation/quicktime-file-format/Color_table_atom/Color_table_flags)

A 16-bit integer.

[`Color table size`](/documentation/quicktime-file-format/Color_table_atom/Color_table_size)

A 16-bit integer that indicates the number of colors in the following color array.

[`Color array`](/documentation/quicktime-file-format/Color_table_atom/Color_array)

An array of colors.


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