Where can I get free JPEG / JFIF / EXIF ​​/ etc specifications?

Question

I want to make a tool for myself (and possibly others, if it works out well) for checking or modifying low-level JPEG files. Similar to TweakPNG , but for JPEG. So far, I have not found any tool that does this.

To do this, I need to read all the relevant specifications. Unfortunately, the official quite expensive , so I'm looking for alternative sources. Is there anything you can recommend that cover as much land as possible?

Answer 1

To answer my own question:

• Part 1 can be downloaded from page W3, and a correction (which contains only patent information) from the ITU page . Direct links: Part 1 , Correction .
• Part 2 I can’t find, but, apparently, it includes only test cases for the compliance of the application of part 1. Useful, but not necessary.
• Part 3 and its amendment detail some extensions and are again available at ITU . Direct links: Part 3 , Amendment .
• Part 4 is also available at ITU , and the details ... I'm not sure yet. Or a few more extensions and the SPIFF file format (I've never heard of this before); or methods for registering new extensions. Maybe both. Anyway, direct link: part 4 .
• Part 5 ... oh wait, there are only 4 parts! But there is a JFIF specification. This one is a little hairy. Obviously this is in version 1.02, and was developed in the good old '92, but this is pretty unofficial. ISO is still working on formalizing it, but in the meantime, ECMA has already done this by simply reformatting it to their typical specification style. In any case, the two things should be the same, as I understand it. You can find them on the W3 and ECMA pages . Direct links: Original , ECMA style .
• Part 6 (I like imaginary parts!) Will be the EXIF ​​standard. According to Wikipedia, it has never been standardized, but everyone adheres to the unofficial JEIDA / CIPA standard. Wikipedia also had a direct link to the latest specification (2010!): EXIF 2.3

It’s good that these are people! Happy JPEG!