/PNG-extensions

Proposals for extending the (A)PNG specification

MIT LicenseMIT

Proposals for extending the (A)PNG specification

  • W3C PNG 1.2 (2003-11-10): Portable Network Graphics (PNG) Specification (Second Edition) = International Standard ISO/IEC 15948:2003 -- Portable Network Graphics (PNG): Functional specification

    • IDAT, IEND, IHDR, PLTE
    • bKGD, cHRM, gAMA, hIST, iCCP, iTXt, pHYs, sBIT, sPLT, sRGB, tEXt, tRNS, zTXt
    • Don't bother with the registration info provided in the W3C/ISO/IEC standard. png-group@w3.org is basically defunct and always has been. Proposals for new chunks or keywords effectively must be run directly through the PNG group mailing list.

  • PNG Extension Registry

    • fRAc, gIFg, gIFt, gIFx, oFFs, sCAL 1995-03-07 PNGEXT 1.2.0
    • pCAL 1997-01-28 PNGEXT 1.2.0
    • sTER 2006-04-15 PNGEXT 1.3.0
    • dSIG 2008-05-01 PNGEXT 1.4.0
    • The PNG Group has a long history of voting down almost every proposal for extension, often for technicalities or on principle grounds.

  • PNG mailing list archive at Sourceforge (incredibly user-hostile, like almost everything on SF.net)

  • PNG Group document repository (FTP) (often slow as fuck)

  • Animated PNG 1.0 currently hosted at Mozilla, hopefully soon being moved to WhatWG or W3C, not endorsed by PNG Group

    • acTL: Animation control chunk
    • fcTL: Frame control chunk
    • fdAT: Frame data chunk