The Conversion tab in the File Formats dialog defines how files should be loaded.
1.Choose Tools | File Formats 
(Beyond Compare | File Formats on macOS) to open the File Formats dialog.
2.Select a picture format.
3.Click the Conversion tab.
4.Choose a Conversion method. When using External program methods, you will need to specify a conversion program with the appropriate path and command-line switches in the Loading edit box.
In order to support filenames with extended characters, make sure to choose the appropriate filename encoding (Unicode or ANSI). The following variables will be replaced with the indicated information:
%s source file
%t target file
%o original file
Conversion programs are only considered successful if they return a zero exit code and generate a nonempty file.
