在哪里可以获得JPEG/JFIF/EXIF/etc的免费规范? [英] Where can I get free specifications of JPEG/JFIF/EXIF/etc?

问题描述

我想为自己(或者如果结果不错的话，可以为他人)做一个工具，用于低级检查/修改JPEG文件.类似于 TweakPNG ，但适用于JPEG.到目前为止，我还没有找到能做到这一点的工具.

I want to make a tool for myself (and maybe others if it comes out good) for low level inspection/modification of JPEG files. Sort of like TweakPNG, but for JPEGs. So far I haven't found any tool that does this.

为此，我需要阅读所有相关规范.不幸的是，官方的是

In order to do that I need to read all the relevant specifications. Unfortunately the official ones are pretty costly, so I'm looking for alternate sources. Is there anything you can recommend which covers as much ground as possible?

推荐答案

要回答我自己的问题:

• 第1部分可以从 W3页面和勘误表(仅包含专利)中下载信息)来自 ITU页面.直接链接:第1部分， ITU再次获得.直接链接: ITU 获得，以及详细信息. ..我还不确定，什么.还有一些扩展名和SPIFF文件格式(以前从未听说过)；或注册新扩展名的方法.可能两者兼而有之.无论如何，直接链接: W3页面和原始，

• Part 1 can be downloaded from the W3 page and the corrigendum (which contains only patent information) from the ITU page. Direct links: Part 1, Corrigendum.
• Part 2 I cannot find, but apparently it only includes test cases for application compliance to part 1. Useful, but not necessary.
• Part 3 and its amendment detail some extensions and are again available from ITU. Direct links: Part 3, Amendment.
• Part 4 is available from ITU as well, and details... I'm not sure yet, what. Either some more extensions and a SPIFF file format (never heard of it before); or methods for registering new extensions. Possibly both. Anyway, direct link: Part 4.
• Part 5... oh, wait, there are only 4 parts! But there is a JFIF specification. That one's a bit hairy. Apparently it's at version 1.02, and was developed in good old '92, but that's pretty unofficial. ISO is still working on formalizing it, but in the meantime ECMA has already done so by simply reformatting it to their typical specification style. Anyways, the two things should be the same, as I understand. You can find them on the W3 page and ECMA page. Direct links: Original, ECMA style.
• Part 6 (I like imaginary parts!) would be the EXIF standard. Accoriding to wikipedia it's never been standardized, but everyone adheres to the unoffical standard by JEIDA/CIPA. Wikipedia also had this direct link to the latest version of the spec (2010!): EXIF 2.3

好吧，乡亲们！ JPEG格式！

Well, that's it folks! Happy JPEGging!

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