From 9aa34b343853e5c5b66df388988e3651ba0ef92b Mon Sep 17 00:00:00 2001 From: Lou Quillio Date: Thu, 14 Jun 2012 15:59:26 -0700 Subject: [PATCH] Manually number "chapters," as chapter numbers are used in the narrative. modified: doc/webp-lossless-bitstream-spec.txt Change-Id: Ice662960ff988a6ff577a8ca5a594e14ba69d4de --- doc/webp-lossless-bitstream-spec.txt | 40 ++++++++++++++-------------- 1 file changed, 20 insertions(+), 20 deletions(-) diff --git a/doc/webp-lossless-bitstream-spec.txt b/doc/webp-lossless-bitstream-spec.txt index 6e5a2e25..3fd0b6d1 100644 --- a/doc/webp-lossless-bitstream-spec.txt +++ b/doc/webp-lossless-bitstream-spec.txt @@ -18,15 +18,15 @@ _2012-06-08_ Abstract -------- -WebP lossless is an image format for lossless compression -of ARGB images. The lossless format stores and restores the pixel -values exactly, including the color values for zero alpha pixels. The +WebP lossless is an image format for lossless compression of ARGB +images. The lossless format stores and restores the pixel values +exactly, including the color values for zero alpha pixels. The format uses subresolution images, recursively embedded into the format -itself, for storing statistical data about the images, such as the -used entropy codes, spatial predictors, color space conversion, and -color table. LZ77, Huffman coding, and a color cache are used for -compression of the bulk data. Decoding speeds faster than PNG have -been demonstrated, as well as 25 % denser compression than what can be +itself, for storing statistical data about the images, such as the used +entropy codes, spatial predictors, color space conversion, and color +table. LZ77, Huffman coding, and a color cache are used for compression +of the bulk data. Decoding speeds faster than PNG have been +demonstrated, as well as 25 % denser compression than what can be achieved using today's PNG format. @@ -93,8 +93,8 @@ scan-line order the next row. -Introduction ------------- +1 Introduction +-------------- This document describes the compressed data representation of a WebP lossless image. It is intended as a detailed reference for WebP lossless @@ -138,8 +138,8 @@ in the bitstream contains the required data to apply the respective inverse transforms. -RIFF Header ------------ +2 RIFF Header +------------- The beginning of the header has the RIFF container. This consist of the following 21 bytes: @@ -170,8 +170,8 @@ The 14-bit dynamics for image size limit the maximum size of a WebP lossless image to 16384✕16384 pixels. -Transformations ---------------- +3 Transformations +----------------- Transformations are reversible manipulations of the image data that can reduce the remaining symbolic entropy by modeling spatial and color @@ -595,8 +595,8 @@ The values are packed into the green component as follows: significant bits of the green value at x / 8. -Image Data ----------- +4 Image Data +------------ Image data is an array of pixel values in scan-line order. We use image data in five different roles: The main role, an auxiliary role related @@ -762,8 +762,8 @@ by inserting every pixel, be it produced by backward referencing or as literals, into the cache in the order they appear in the stream. -Entropy Code ------------- +5 Entropy Code +-------------- ### Huffman coding @@ -944,8 +944,8 @@ length of the Huffman code: * k = 4, length = 40. -Overall Structure of the Format -------------------------------- +6 Overall Structure of the Format +--------------------------------- Below there is a eagles-eye-view into the format in Backus-Naur form. It does not cover all details. End-of-image EOI is only implicitly coded