Run Length Encoding
Computer Science: OCR A Level, topic 3.1.2
Run Length Encoding
One compression algorithm you need to learn is run length encoding (RLE).
Run length encoding
- Run length encoding (RLE) is a form of lossless compression that replaces repeating sequences of 0s and 1s with more efficient representations.
- Each repeating string will be replaced by a code which represents the character and the amount of times it is to be repeated.
In images
- In images, adjacent pixels are likely to have similar but slightly different colours.
- Image compression algorithms can group these pixels together and replace them with a single 'average' colour. This is a lossy process.
- The RLE algorithm can then be applied to the new image.
- While the step using RLE is still lossless, the grouping of pixels beforehand makes the whole process lossy.
Test yourself on Run Length Encoding
Why is run length encoding difficult in images?
What type of compression is run-length encoding?