W3C

PNG Recommendation, Second Edition Errata

This version:
http://www.w3.org/2003/10/REC-PNG-20031110-errata
Last modified:
$Date: 2009/06/25 23:57:49 $
This document records known errors in the document:
http://www.w3.org/TR/2003/REC-PNG-20031110/
The latest version of the PNG specification is at:
http://www.w3.org/TR/PNG

Public comments on this W3C Recommendation are welcome. Please send them to the archived list png-group@w3.org .


Typographic error in description of tRNS

Category:
2. Corrections that do not affect conformance
Date:
2009 Jun 25
Reported by:
Glenn Randers-Pehrson
Status:
Proposed

Description

For the tRNS chunk, Colour type 2, a typographical error was introduced in the second edition of PNG: the blue and green channels were switched. The first edition of PNG had the correct order, Red, Green, Blue. This is the same order as is used throughout the specification, and implementations have silently corrected for the obvious error.

Change

In section 11.3.2.1 tRNS Transparency change:

Colour type 0
Grey sample value 2 bytes
Colour type 2
Red sample value 2 bytes
Blue sample value 2 bytes
Green sample value 2 bytes
Colour type 3
Alpha for palette index 0 1 byte
Alpha for palette index 1 1 byte
...etc... 1 byte

to:

Colour type 0
Grey sample value 2 bytes
Colour type 2
Red sample value 2 bytes
Green sample value 2 bytes
Blue sample value 2 bytes
Colour type 3
Alpha for palette index 0 1 byte
Alpha for palette index 1 1 byte
...etc... 1 byte

Chris Lilley