image-dired-cmd-read-exif-data-options

image-dired-cmd-read-exif-data-options is a variable defined in `image-dired.el'.
Its value is

"%p -s -s -s -%t \"%f\""

Documentation:
Format of command used to read EXIF data.
Available options are %p which is replaced by
`image-dired-cmd-write-exif-data-program', %f which is replaced
by the image file name and %t which is replaced by the tag name.

You can customize this variable.