Angle Measurement Definition

Different image formats are displayed with their origin in different relative locations in the image window. The convention for FITS format is to display the image with the origin in the lower left corner but other formats display the origin in the upper left corner. This means that angles are measured differently in FITS format and other formats. The convention for graphics software is to measure positive angle going clockwise from the positive x axis but it may be different for a FITS image that does have or does not have a World Coordinate System Calibration. Therefore, to accommodate all conventions, angle measurements follow a different sense when measured in different format images:


Related Topics

Image Display Orientation, Pixel Coordinate Definition, Subpixel Coordinate Definition, World Coordinate System