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obscure features of jpeg [ad9922f6]

Tags: computers, articles

1. Progessive JPEGs

  • contains data in a different order, lets the decoder produce a full-sized image from first chunk of file with low detail, then fill details in as image loads
  • originally made for web browsers over slow connections

2. Multi-Scan JPEGs

  • Regular JPEGs are single scan sequential: all data is stored from top to bottom, with colors and coefficients in full

  • Multi-scan stores this in a separate way, allows JPEGs to be scanned multiple times, each scan loading additional data

    • Means that first load can show sketch of image, second load can show colors, etc