H JPEG Support

Contents

• H.1 Introduction
• H.2 Required support

H.1 Introduction

This appendix is normative.

This appendix specifies the JPEG support required by SVG Tiny 1.2 implementations. The required support is targeted at specifying a level of functionality known to be compatibly supported within the industry and without licensing issues.

In general when people refer to JPEG [JPEG], they actually mean JPEG compressed images within the JFIF [JFIF] file format. JFIF was created by the Independent JPEG Group (IJG) for storing a single JPEG-compressed image in a file.

H.2 Required support

SVG Viewers are required to support JPEG images stored in a JFIF file [JFIF]. Other transport or storage mechanisms may be supported.

The following coding processes defined by the JPEG specification [JPEG], in Table 1, section 4.11, must be supported:

• Baseline process
• Extended DCT-based processes (with the exception of arithmetic coding).

The following statements also apply:

• 8-bit samples must be supported. 12-bit samples may be supported ([JPEG], section 4.7).
• Support for the DNL Marker ([JPEG], section 3.2) is not required.
• Support for non-integer sampling ratios is not required ([JPEG], section A.1.1).

The following encoding processes are not required, but may be supported:

• Complete Extended DCT-based processes
• Lossless Processes
• Hierarchical Processes

SVG Tiny 1.2 user agents should convert Y,Cb,Cr values compressed in the JPEG image to RGB as defined in the JFIF specification [JFIF] and may assume, in the absence of a color profile, that the RGB values are sRGB.