These are all the possible values for the IG_ISIS_TAG_ORIENTATION, IG_ISIS_TAG_SCANORIENTATION and IG_ISIS_TAG_DATAORIENTATION tags.
IG_ISIS_ORIENTATION_PORT | Portrait (0°). |
IG_ISIS_ORIENTATION_LAND | Landscape (90° ccw). |
IG_ISIS_ORIENTATION_180 | Upside down portrait (180° ccw). |
IG_ISIS_ORIENTATION_270 | Upside down landscape (270° ccw). |
IG_ISIS_ORIENTATION_PORTM | Portrait mirrored. |
IG_ISIS_ORIENTATION_LANDM | Landscape mirrored. |
IG_ISIS_ORIENTATION_180M | Upside down portrait mirrored. |
IG_ISIS_ORIENTATION_270M | Upside down landscape mirrored. |