Multimedia Compression
Compression reduces data size for storage and transmission. Without it, multimedia is impractical.
Redundancy Types
Statistical (frequency), spatial (neighbouring pixels), temporal (consecutive frames), psychovisual/psychoacoustic (imperceptible info).
Lossless
RLE, Huffman coding, LZW (GIF, ZIP), arithmetic coding. Preserves all original data.
Lossy
Transform coding (DCT, wavelet), quantisation. Higher quantisation = smaller file = lower quality.
JPEG
RGB→YCbCr, chrominance subsampling, 8×8 DCT, quantisation, zigzag, Huffman coding. Quality 1-100.
MPEG
MPEG-1 (VCD), MPEG-2 (DVD), MPEG-4/H.264 (internet), MPEG-H/H.265 (next gen).
Metrics
Compression ratio, bit rate, PSNR, SSIM. Rate-distortion curves show quality-size trade-off.
Summary
Compression is essential for practical multimedia. Understanding lossless/lossy techniques and standards enables informed decisions.