Custom Exif Tags

Question

I am using exiv2 to manipulate metadata in a jpeg file. I need to write more information related to image processing into the metadata. Is is possible to create Custom Exif

Answer 1

Based on my research EXIF tags are conformed to a standard set of tags as described here.

Within the standards document it states (in reference to EXIF tags),

A registration system is used for character codes to avoid duplication. When a character code is registered, a standard document is indicated in the reference column to indicate the character format specification. If a character code is used for which there is no clear specification like Shift-JIS in Japan, Undefined is designated.

Therefore its my understanding that there is a standard set of tags (the registered tags) otherwise when you query it using a tool such as exiftool it will show up as 'Undefined'.

So in order to have a tag that is recognizable by tools or other entities, you'd need to register your tag to become part of the standardized tags.