topic 1.3 compression```

why do we compress files

to save storage space and reduce the time taken to transmit data, less bandwidth used to download

what is lossless file compression

original data is preserved used when all data the data is needed

what is lossy compression

original data is lost and file cannot be reconstructed - lowers resolution

what happens when u compress a sound file

reduce amplitude range, consecutive sounds group together

what happens when you compress an image (lossy)

reduces bit depth, number of colours and resolution

what happens when you compress images (lossless)

RLE replaces sequences of the same colour pixel with colour code and number of identical pixels

what is run length encoding

identifies groups of repeated characters and replaces them with a copy of the character and the number of times it occurs.

what are limitations of RLE

there. may not be many sequences of the same colour, so it would be 1 which adds to file size.