Principles of Digital Image Compression
For black and white images, each pixel is represented by one bit. These images are sometimes referred to as bi-level, binary, or bi-tonal images.
For gray scale images, each pixel is represented by a luminance (or intensity) level. For pictorial images, typical gray scale images are represented by 256 gray levels, or 8 bits. For document images, 4–7 bits are usually sufficient.
Color images have multiple components. Each pixel of a color image can be represented by luminance and chrominance components. For instance, the NTSC (National Television Systems Committee) transmission system uses the luminance Y, and two chrominances I and Q to represent color. The CCITT H.261 and MPEG standards use the luminance Y and two chrominances C B and C R to represent color.
KeywordsCompression Ratio Image Compression Document Image Gray Scale Image Compression Algorithm
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