These are all the possible values for the IG_ISIS_TAG_FILLORDER tag.
IG_ISIS_FILLORDER_MSBLEFT | Pixels are arranged within a byte such that pixels with lower column values are stored in the higher-order bits of the byte. The first bit of the first byte corresponds to the first pixel on an uncompressed binary page. |
IG_ISIS_FILLORDER_MSBRIGHT | Pixels are arranged within a byte such that pixels with lower column values are stored in the lower order bits of the byte. The last bit of the first byte corresponds to the first pixel on an uncompressed binary page. |