RFC 2083 (rfc2083) - Page 3 of 102

PNG (Portable Network Graphics) Specification Version 1

RFC 2083            PNG: Portable Network Graphics            March 1997


      9.5. Suggested palettes ....................................... 48
      9.6. Filter selection ......................................... 49
      9.7. Text chunk processing .................................... 49
      9.8. Use of private chunks .................................... 50
      9.9. Private type and method codes ............................ 51
   10. Recommendations for Decoders ................................. 51
      10.1. Error checking .......................................... 52
      10.2. Pixel dimensions ........................................ 52
      10.3. Truecolor image handling ................................ 52
      10.4. Sample depth rescaling .................................. 53
      10.5. Decoder gamma handling .................................. 54
      10.6. Decoder color handling .................................. 56
      10.7. Background color ........................................ 57
      10.8. Alpha channel processing ................................ 58
      10.9. Progressive display ..................................... 62
      10.10. Suggested-palette and histogram usage .................. 63
      10.11. Text chunk processing .................................. 64
   11. Glossary ..................................................... 65
   12. Appendix: Rationale .......................................... 69
      12.1. Why a new file format? .................................. 69
      12.2. Why these features? ..................................... 70
      12.3. Why not these features? ................................. 70
      12.4. Why not use format X? ................................... 72
      12.5. Byte order .............................................. 73
      12.6. Interlacing ............................................. 73
      12.7. Why gamma? .............................................. 73
      12.8. Non-premultiplied alpha ................................. 75
      12.9. Filtering ............................................... 75
      12.10. Text strings ........................................... 76
      12.11. PNG file signature ..................................... 77
      12.12. Chunk layout ........................................... 77
      12.13. Chunk naming conventions ............................... 78
      12.14. Palette histograms ..................................... 80
   13. Appendix: Gamma Tutorial ..................................... 81
   14. Appendix: Color Tutorial ..................................... 89
   15. Appendix: Sample CRC Code .................................... 94
   16. Appendix: Online Resources ................................... 96
   17. Appendix: Revision History ................................... 96
   18. References ................................................... 97
   19. Credits ......................................................100











Boutell, et. al.             Informational