Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
%d gives the directory component of the input file, as it appears on the command line or whatever. If there is no directory component, we get a warning.
I think it is a bug/mistake to say " unknown image property "%d".
Seems to me that it should not give that error message, but simply return an empty result. That is, since there was no formal directory in the filename, the directory is properly an empty string value.