FITS Image Orientation
FITS format images are conventionally displayed with the row number increasing upward. If your FITS format image was saved from the camera upside down, with row number increasing downward, then it can be displayed correctly by setting a program option. Before opening an upside-down FITS image, check the Flip FITS Images option in the Open dialog options or in the Other page of the Mira Preferences dialog.
The comparison below shows row number increasing upward and downward. In both cases, Mira measures the same row position and calibrated world coordinate for a given object in the image.
In the conventional display orientation, row number increases upward.
In the unconventional display orientation, as shown below, row number increases downward.
Image Display Orientation, Image Coordinate System, Pixel Coordinate Definition