The PNG Guide is an eBook based on Greg Roelofs' book, originally published by O'Reilly.


This section, added according to the requirements of paragraph 4.I of the GNU FDL, describes the history of the document, not of the PNG format. (It may be moved to a separate page if it grows too unwieldy for the Preface.)

Version 1

  • Title:   PNG: The Definitive Guide
  • Year:   1999
  • Author:   Greg Roelofs
  • Publisher:   O'Reilly & Associates

The first edition was published in softcover (paper) format in June 1999.

Version 2

This is the first online version of the book, released under the GNU Free Documentation License and published in July 2003. The original title and cover image are used with permission of the original publisher (O'Reilly and Associates). The complete text may be downloaded from

The principal change, obviously, is the fact that Version 2 is an electronic (HTML) edition rather than paper, intended to be read using any reasonably modern web browser. The original troff source was automatically converted by Lenny Muellner to HTML, which was then modified as follows:

  1. Filenames and all internal HTML references (chapters, subsections, table numbers, figure numbers) were off by one in the auto-conversion; fixed.
  2. Expanded table of contents and navigation sections at the top of each chapter to include subsections, not just chapters or top-level sections; added inter-chapter navigation bars (previous/contents/next).
  3. Converted ``Parts'' from verbatim replications of multiple chapters to corresponding excerpts from the table of contents.
  4. Changed auto-converted ``text images'' back to plain text using Unicode and Latin-1 entities (gamma, mu, Delta, delta, right arrow, a-with-ring, etc.).
  5. Added cover page, title page, copyright page, dedication, list of tables, list of figures, pages for original color plates (including captions), and license page.
  6. Recreated index and linked page numbers to appropriate HTML anchors; added new entries.
  7. Converted GIFs (from auto-conversion) to PNGs; rebuilt inlined, shrunken, grayscale figures with original, color source images wherever possible; added links to full-scale source images where necessary.
  8. Converted four text-mode listings in Chapter 9 to tables and updated table references accordingly; added mention of PNG chapter in the Lossless Compression Handbook.
  9. Restored 99 lines of missing text(!) in Chapter 14 (lost in auto-conversion, apparently).
  10. Corrected all errata noted on both O'Reilly's and the author's web pages, as well as several others in the index and bibliography.
  11. Updated web links associated with the book or its author (particularly
  12. Reverted some O'Reillyisms (Gimp, frontend, backend) to original text (GIMP, front end [noun] or front-end [adjective], etc.).
  13. Cleaned up various bits of formatting.
  14. Added ``About'' and ``History'' sections to preface. These sections (together with some other additions) are in green text to distinguish them more easily from the original text.

As noted in the previous section, I intend to continue updating the HTML version, but this will probably be limited to fixing broken links and tying some of the sections more closely to appropriate pages on the PNG web site. Any such changes will be noted here in an ongoing changelog.

Last Update: 2010-Nov-26