Question

I have found various code and libraries for editing Exif.

But they are only lossless when the image width and height is multiple of 16.

I am looking for a library (or even a way to do it myself) to edit just the Exif portion in a JPEG file (or add Exif data if it doesn’t exist yet), leaving the other data unmodified. Isn’t that possible?

So far I could only locate the Exif portion (starts with 0xFFE1) but I don’t understand how to read the data.

Answer 1

Here are the specifications for the Exif interchange format, if you plan to code your own library for editing tags.

http://www.exif.org/specifications.html

Here’s a library written in Perl that meets your needs that you may be able to learn from:

http://www.sno.phy.queensu.ca/~phil/exiftool/

Here’s a decent .NET library for Exif evaluation from The Code Project:

http://www.codeproject.com/KB/graphics/exiftagcol.aspx