The JPEG file format has included the ability to include photographic metadata such as shutterspeed, aperture, focal length, etc.

TIFF files, being very general, are well set up to include custom metadata.

I'd like my program, FractalWorks, to be able to include the settings for a fractal image in a JPEG and/or TIFF image of the file. Then, if a user opens the file in my app, I could recreate the original fractal from the settings in the file.

I've been looking into the EXIF spec. It looks like tags are pre-defined and reserved. That means I could not readily create my own tags.

I would like to use the same scheme for both JPEG and TIFF images, and would like for my extra metadata to be passed, unmodified, by well behaved image editing programs and web servers.

My current thinking is to use the user comment field. I would use ASCII for the user comment, and the first few characters of the comment would mark the comment as a FractalWorks comment. I would then include an application-specific URL for the plot. (FractalWorks already includes the ability to encode the settings needed to reproduce a fractal into a custom URL, which is ASCII.) ASCII isn't the most efficient way to encode plot settings, but it is easy to use and understand.

Have any of you other developers worked with image file metadata before? If so, can you suggest a better way?



Regards,

Duncan C