JPEG Compression

  What is JPEG?

• "Joint Photographic Expert Group" -- an international standard in 1992.

• Works with colour and greyscale images, Many applications e.g., satellite, medical, ...

JPEG compression involves the following:

• Encoding (Fig 7.12)

  

  JPEG Encoding

• Decoding - Reverse the order for encoding

The Major Steps in JPEG Coding involve:

• DCT (Discrete Cosine Transformation)

• Quantization

• Zigzag Scan

• DPCM on DC component

• RLE on AC Components

• Entropy Coding

The DCT has already been introduced (Section 7.5.4) we now summarise the other steps.