What Is Compression?

Compression can be found in a multitude of files. This includes images, audio files, videos, documents and more. Depending on the file, Compression works in different ways. Compression in general, however, is the reduction of data which causes the file to use fewer bits than the original file. There are two major types of Compression: lossy and lossless Compression. While lossless Compression removes bits by identifying statistical redundancy, leaving the general information of the file untouched, lossy Compression removes unnecessary or not as important information. Thus, lossy Compression is visible (image, video) or audible (audio) in the resulting files when compared to the original representation.

When checking your file for secret or hidden information, there might be various representations of Compression available. In some instances, it can express that no Compression was applied to the file in question by either having the value “none” or “uncompressed” or something along that line. If Compression was applied to the file, the value usually states the Compression method used, such as “JPEG”, “H264” or others available for the respective file format.