why PI shows pictures "upside down" comparing to other packages like Maxim where picture will be show in its normal way with the Head raised UP?
Because by default, PI uses the "professional convention" for FITS image coordinates: vertical coordinates grow from bottom to top, and the origin of coordinates is the bottom left corner. This is the convention used by virtually all professional observatories (HST, CAHA, IAC, ESO, Gemini, ...) and CCD cameras.
The "amateur convention" is just the opposite: vertical coordinates grow from top to bottom and the origin is at the top left corner, just as in the rest of image formats.
Of course you can change the default FITS orientation:
- Open the Format Explorer window.
- Double click on the FITS item of the left column
- On the FITS Format Preferences dialog, select the "Upper left corner - up-bottom" option for
Coordinate origin, in the
Miscellaneous Options group box.
PI will remember your selection and will apply it to read and write FITS images.
