Which compression preserves all original data?

Which compression preserves all original data?

• A. Lossless
• B. Lossy
• C. Pixel
• D. Metadata

Answer: (A)

Compression can be lossless or lossy. The one that preserves every bit of the original data is lossless compression, because it reduces file size without discarding information, so you can reconstruct the exact original file from the compressed form. Lossless methods, like PNG for images or ZIP for files, keep all data intact. Lossy compression, on the other hand, drops some information to achieve higher compression, so the decompressed data is not exactly the same as the original. Pixel and Metadata aren’t compression methods themselves—Pixel refers to image elements, and Metadata is extra information about the data—so they don’t describe a way to guarantee exact restoration. So the option that preserves all original data is lossless.

Compression can be lossless or lossy. The one that preserves every bit of the original data is lossless compression, because it reduces file size without discarding information, so you can reconstruct the exact original file from the compressed form. Lossless methods, like PNG for images or ZIP for files, keep all data intact. Lossy compression, on the other hand, drops some information to achieve higher compression, so the decompressed data is not exactly the same as the original. Pixel and Metadata aren’t compression methods themselves—Pixel refers to image elements, and Metadata is extra information about the data—so they don’t describe a way to guarantee exact restoration. So the option that preserves all original data is lossless.