Overview:

bgsub provides a quick, interactive way to perform column-based background subtraction as well as row-based ramping on FITS files.

How to use:

Dragging the mouse with the left button in the main window defines a 'normal' region which the program uses to establish background levels to be subtracted. Every column is treated separately, with the averages in that column within the normal region being considered the background level for that particular column. The graph below the main window shows intensities within the 'normal' region. For a similar graph of vertical intensities, drag the right mouse button to define a second, vertically-oriented region, and a graph will appear to the left of the window displaying this information. Vertical ramping is performed by entering numbers into the text fields at the bottom right and pressing enter. The 'next' and 'previous' buttons go forward or backwards through the FITS files in the selected directory. 'save' saves the modified FITS image into the 'corrected' directory inside the 'bgsub' directory, and advances to the next frame if there is one.