Wavelet compression is a technique used to compress audio and video signals, which works best for high-contrast images and short audio. It uses wavelet transformations to gather information about the file, which can result in a lossless or lossy compressed file. The process involves treating the image as a series of wavelets, measuring pixel coefficients, and decomposing them by averaging adjacent pixels. The final size of the compressed file depends on the desired quality, and wavelet compression can use either lossless or lossy methods.
Wavelet compression is a technique used to compress video and audio signals. Works best for compressing high-contrast images and short audio. Because video and audio files are often very large, compression is important because it allows information to be shared over a network or sent by email faster than the uncompressed file could be. Wavelet compression uses a process called wavelet transformations to gather the necessary information about the file. The resulting file can be lossless, meaning it’s as good as the original, or lossy, meaning some information has been lost.
For example, to compress a photograph using wavelet compression, the entire image is treated as a series of wavelets. Wavelets are pixel-to-pixel changes measured by a single pixel’s deviation from zero. The distance of the deviation is recorded as a coefficient, an integer that measures some property or characteristic. In this case, the coefficient measures the color of the pixel. The process of measuring and recording pixel coefficients is called a wavelet transform.
At this stage of wavelet compression, no compression has occurred yet. The image has just been translated into a form that the computer can work with. Instead of a color image, the computer now has a series of numbers. The next step in wavelet compression is a process called decomposition.
During decomposition, the coefficients of adjacent pixels are averaged. Averaging produces a simplified version of the wave, reducing the description of the image. This process is repeated until the image is fully compressed. The more times you repeat the process, the smaller the data file can be and the faster the file will be transmitted.
The final size of the compressed file depends not only on the size of the original file, but also on the desired quality of the final product. Sometimes when a file is unzipped, information that the computer deems unnecessary is discarded to allow the file to shrink. This is known as lossy compression and results in a file that is not as good as the original.
Wavelet compression can also use a lossless method, where no information is thrown away. This results in a compressed file that, when decompressed, is exactly the same quality as the original file. The tradeoff is that a file compressed with a lossless method will be larger than one compressed with a lossy method.
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