Lossy compression reduces a representation while permitting irreversible changes to the original. The encoder can map distinct inputs to the same output, so its decoder cannot recover both originals exactly. The useful question becomes how much storage is saved for an acceptable amount of distortion: mean squared error is one numerical criterion, but it does not by itself measure how noticeable a visual change is.
For example, storing the arithmetic mean of four grayscale pixels retains their average shade while discarding their arrangement. Blocks and both produce 50. The former has detail and the latter is uniform, yet the decoder receives the same value. Lossy block averaging makes this ambiguity, its bit saving and its mean squared error exact.
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Lossy compression is a data encoding method that reduces file size by permanently eliminating certain information, particularly redundant or less important data. This technique is commonly used in various media formats such as audio, video, and images, where a perfect reproduction of the original is not necessary for most applications. **Key Characteristics of Lossy Compression:** 1. **Data Loss:** Some data is lost during the compression process, which cannot be restored in its original form.
