IMAGING GLOSSARY8-bit image (digital imaging)
An image where each pixel has 8-bits of information. An 8-bit pixel contains
one of 256 possible values.
There are two common types of 8-bit images: gray scale and indexed color.
In a gray-scale image, each pixel takes one of 256 shades of gray and the
shades are linearly distributed from 0 (black) to 256 (white). An 8-bit
gray-scale image does not require a palette but may have one.
An indexed color image is always a palette image. Each pixel is used as
an index to the palette. These images can have up to 256 different colors.
This includes hues as well as shades. Indexed 8-bit images are good for low
color resolution images that do not need processing. They are 3 times
smaller than full-color RGB images, but because the pixel values are not
linear, many image-processing algorithms cannot work with them. They must be
promoted to 24-bit for image processing.
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