I tend to think that there is no way to modify the resolution on a JP2 header on Windows although I found that on Linux, there are such a tool and using ChatGPT, it gave me the name of jp2modify, tool that I was not able to find. So could you tell me whether this information is held in the JP2 header ? And if the answer is yes, which Windows tool could do the job ?
I have been using several tools (IrfanView, ImageMagick) on Windows (my target platform) to specify the actual resolution of a JP2 image. ImageMagick identify does not provide resolution information in verbose mode (-format provides a value of 72 ppi).
The resolution information of a JP2 image can be stored in the JP2 header. The header of a JP2 file contains various metadata about the image modifying this information directly within the JP2 header is not a straightforward task on Windows
Regarding Windows tools for modifying JP2 image resolution, it's worth noting that ImageMagick, which you mentioned, does support JP2 format.
If you're specifically looking for a Windows tool that can modify the resolution information in the JP2 header, I'm not aware of any dedicated software for this purpose. However, you may try using more specialized JP2 manipulation tools or libraries like Kakadu or OpenJPEG, which provide more advanced functionality for working with JP2 images.