optional_depends  "%JPEG"                                              \
                  "--enable-jpeg"                                      \
                  "--disable-jpeg"                                     \
                  "for JPEG usage (required for JPEG compression)"

optional_depends  "zlib"                                               \
                  "--enable-zlib"                                      \
                  "--disable-zlib"                                     \
                  "for Zlib usage (required for Deflate compression)"

optional_depends  "jbigkit"                                            \
                  "--enable-jbig"                                      \
                  "--disable-jbig"                                     \
                  "for JBIG-KIT usage (required for JBIG compression)"
