On Debian 10, I followed the instructions to build gpg4win but got an error when running:
```
$ ./autogen.sh --build-w32
...
configure: convert is missing
configure: error:
***
*** Required tools not found. Please consult the above messages
*** and install them before running configure again.
***
Prior to this step, I installed all the packages listed under Basic Requirements. However, it appears that imagemagick (which contains convert) was not included.
Adding imagemagick to the build requirements resolved the issue.
```
Fix available here: https://github.com/drichardson/gpg4win/commits/fix-convert-missing