Specifies image orientation units.

Values:

IG_ORIENT_TOP_LEFT	Image orientation is Row0=Top, Col0=Left (normal / portrait).
IG_ORIENT_TOP_RIGHT	Image orientation is Row0=Top, Col0=Right (flipped horizontally).
IG_ORIENT_BOTTOM_RIGHT	Image orientation is Row0=Bottom, Col0=Right (rotated by 180 degrees).
IG_ORIENT_BOTTOM_LEFT	Image orientation is Row0=Bottom, Col0=Left (flipped vertically).
IG_ORIENT_LEFT_TOP	Image orientation is Row0=Left, Col0=Top (rotated by 90 degrees counterclockwise and then flipped vertically).
IG_ORIENT_RIGHT_TOP	Image orientation is Row0=Right, Col0=Top (rotated by 90 degrees clockwise / landscape).
IG_ORIENT_RIGHT_BOTTOM	Image orientation is Row0=Right, Col0=Bottom (rotated by 90 degrees clockwise and then flipped vertically).
IG_ORIENT_LEFT_BOTTOM	Image orientation is Row0=Left, Col0=Bottom (rotated by 90 degrees counterclockwise / landscape).

Remarks:

There are 8 possible orientations. This enum labels them according to where the first row (row 0) and first col (col 0) of the image data is to be displayed. Regular images are displayed with row 0 at the top and column 0 at the left. This corresponds to IG_ORIENT_TOP_LEFT mode. The other orientations are combinations of flips and rotates. Portrait is usually IG_ORIENT_TOP_LEFT, and Landscape is either IG_ORIENT_RIGHT_TOP or IG_ORIENT_LEFT_BOTTOM.