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Project Proposal: Dynamic Adaptive JPEG

Team C:

R09922028 施承志

R09922071 劉俊緯

R09922091 張庭與

R09944021 鍾起鳴

Idea Origin

JPEG codec divides image into 8x8 blocks for encoding. However, real-world images often constains large blocks with few details. If we can design a codec which takes image detail into consider, it could improve the compression rate of an real-life image.

Base Idea

  • Modify JPEG so that it can divide image into coding blocks of different sizes based on local image detail.

Challenge

Encoding

  • An additional table for block division records.
  • Larger DC difference between larger blocks

Encoder

  • Image detail recognition
  • DCT for different block sizes
  • Different quantisation

Decoder

  • DCT for different block sizes

Expected effect

  • Higher compression ratio (i.e. smaller image size) for general images
  • Not much more computational costs
  • Not much worse in special cases