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Manually number "chapters," as chapter numbers are used in the narrative.

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modified:   doc/webp-lossless-bitstream-spec.txt

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Lou Quillio 2012-06-14 15:59:26 -07:00
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doc/webp-lossless-bitstream-spec.txt
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@ -18,15 +18,15 @@ _2012-06-08_
Abstract Abstract
-------- --------
WebP lossless is an image format for lossless compression WebP lossless is an image format for lossless compression of ARGB
of ARGB images. The lossless format stores and restores the pixel images. The lossless format stores and restores the pixel values
values exactly, including the color values for zero alpha pixels. The exactly, including the color values for zero alpha pixels. The
format uses subresolution images, recursively embedded into the format format uses subresolution images, recursively embedded into the format
itself, for storing statistical data about the images, such as the itself, for storing statistical data about the images, such as the used
used entropy codes, spatial predictors, color space conversion, and entropy codes, spatial predictors, color space conversion, and color
color table. LZ77, Huffman coding, and a color cache are used for table. LZ77, Huffman coding, and a color cache are used for compression
compression of the bulk data. Decoding speeds faster than PNG have of the bulk data. Decoding speeds faster than PNG have been
been demonstrated, as well as 25 % denser compression than what can be demonstrated, as well as 25 % denser compression than what can be
achieved using today's PNG format. achieved using today's PNG format.
@ -93,8 +93,8 @@ scan-line order
the next row. the next row.
Introduction 1 Introduction
------------ --------------
This document describes the compressed data representation of a WebP This document describes the compressed data representation of a WebP
lossless image. It is intended as a detailed reference for WebP lossless 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. inverse transforms.
RIFF Header 2 RIFF Header
----------- -------------
The beginning of the header has the RIFF container. This consist of the The beginning of the header has the RIFF container. This consist of the
following 21 bytes: 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. lossless image to 16384✕16384 pixels.
Transformations 3 Transformations
--------------- -----------------
Transformations are reversible manipulations of the image data that can Transformations are reversible manipulations of the image data that can
reduce the remaining symbolic entropy by modeling spatial and color 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. 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 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 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. literals, into the cache in the order they appear in the stream.
Entropy Code 5 Entropy Code
------------ --------------
### Huffman coding ### Huffman coding
@ -944,8 +944,8 @@ length of the Huffman code:
* k = 4, length = 40. * 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 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 does not cover all details. End-of-image EOI is only implicitly coded