Indexed Color

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Indexed Color

Indexed color is a method of reducing the number of colors used in a computer image by storing a table of colors that are used in the image and associating each pixel with an index into the table. This reduces the amount of memory required to store the image because only the index values need to be stored, instead of the full color values for each pixel.

What does Indexed Color Mean?

Indexed color is a computer graphics technique that uses a limited number of colors, called a palette, to represent a larger range of colors. Each color in the palette is assigned an index, and the image data stores the index of the color used for each Pixel. This approach allows for efficient storage and manipulation of images with a reduced file size compared to true color formats, which store the RGB or RGBA values for each pixel.

Indexed color images typically have a Color Depth of 8 bits per pixel, allowing for a palette of up to 256 colors. However, larger palettes are also possible, allowing for more nuanced color representations. By carefully selecting the colors in the palette, artists can create images with a wide range of tones and hues while maintaining a reasonable file size.

The key advantage of indexed color is its ability to reduce file sizes, making it suitable for applications where storage space is limited. This approach was particularly valuable in the early days of computing when memory and storage capacities were constrained. It is still widely used in applications such as:

  • Video games: Indexed color is commonly employed in video games to create pixel art and minimize file sizes, allowing for a responsive gaming experience with limited memory constraints.
  • Web graphics: In the early days of the internet, when bandwidth was limited, indexed color was frequently used for web graphics to reduce load times and improve User Experience.
  • Animation: Indexed color is also used in traditional animation to store and manipulate large images efficiently, facilitating the creation of complex and detailed animations.

History of Indexed Color

The concept of indexed color emerged in the early days of computing, when hardware limitations prevented the storage of full-color images. In the 1970s and 1980s, personal computers and video game consoles often used indexed color to display graphics efficiently.

The IBM PC introduced in 1981 featured a graphics Adapter that supported a 16-color palette with a limited resolution of 320×200 pixels. This standard became widely adopted and influenced the development of early video games and business software.

Throughout the 1980s and 1990s, indexed color continued to be used in various applications, including home computers, video game consoles, and early web graphics. As technology advanced, the number of colors supported by indexed color palettes increased, providing more flexibility for artists and designers.

In the late 1990s and early 2000s, true color formats such as RGB and RGBA gained popularity, offering a wider range of colors and eliminating the need for a predefined palette. However, indexed color remains an important technique for certain applications where file size and efficiency are essential considerations.