Excellent, thanks...

It will be interesting to look at the code changes to see how you did it ...

Certainly, would be useful if you could modify the JFIF header as well ...
This would enable me to normalise the resolution in all possible places
to ensure that there is no possible chance of an app seeing the image the wrong size...
Not a huge priority though....initially I will just normalise the 'other' resolution values to the current value of the JFIF header..

May I take this opportunity to say what an excellent piece of work this is...
It must of taken you quite some time to amass the specific knowledge of all the supported data