kai.strehl
==========

.. py:module:: kai.strehl


Functions
---------

.. autoapisummary::

   kai.strehl.calc_strehl
   kai.strehl.calc_strehl_single
   kai.strehl.calc_peak_flux_ratio
   kai.strehl.fit_gaussian2d
   kai.strehl.fwhm_to_stddev
   kai.strehl.stddev_to_fwhm


Module Contents
---------------

.. py:function:: calc_strehl(file_list, out_file, apersize=0.3, instrument=instruments.default_inst)

   
   Calculate the Strehl, FWHM, and RMS WFE for each image in a 
   list of files. The output is stored into the specified <out_file>
   text file. The FWHM (and Strehl) is calculated over the specified 
   aperture size using a 2D gaussian fit. The Strehl is estimated by
   using the star specified in the *.coo (one for each *.fits file) 
   file and taking the max pixel flux / wide-aperture flux and normalizing
   by the same on a diffraction-limited image. Note that the diffraction
   limited image comes from an external file. 

   The format of the *.coo file should be:
   xpix  ypix   # everything else

   The diffraction limited images come with the pipeline. For Keck, they are
   all obtained empirically using the NIRC2 camera and filters and they
   are sampled at 0.009952 arcsec / pixel. We will resample them as necessary.
   We will play fast and loose with them and use them for both NIRC2 and OSIRIS. 
   They will be resampled as needed.















   ..
       !! processed by numpydoc !!

.. py:function:: calc_strehl_single(img_file, radius, dl_peak_flux_ratio, instrument=instruments.default_inst)

.. py:function:: calc_peak_flux_ratio(img, coords, radius, skysub=True)

   
   img : 2D numpy array
       The image on which to calculate the flux ratio of the peak to a 
       wide-aperture.

   coords : list or numpy array, length = 2
       The x and y position of the source.

   radius : int
       The radius, in pixels, of the wide-aperture. 















   ..
       !! processed by numpydoc !!

.. py:function:: fit_gaussian2d(img, coords, boxsize, plot=False, fwhm_min=1.7, fwhm_max=30, pos_delta_max=1.7)

   
   Calculate the FWHM of an objected located at the pixel
   coordinates in the image. The FWHM will be estimated 
   from a cutout with the specified boxsize.


   :Parameters:

       **img** : ndarray, 2D
           The image where a star is located for calculating a FWHM.

       **coords** : len=2 ndarray
           The [x, y] pixel position of the star in the image. 

       **boxsize** : int
           The size of the box (on the side), in pixels.

       **fwhm_min** : float, optional
           The minimum allowed FWHM for constraining the fit (pixels).

       **fwhm_max** : float, optional
           The maximum allowed FWHM for constraining the fit (pixels).

       **pos_delta_max** : float, optional
           The maximum allowed positional offset for constraining the fit (pixels).
           This ensures that the fitter doesn't wonder off to a bad pixel.














   ..
       !! processed by numpydoc !!

.. py:function:: fwhm_to_stddev(fwhm)

.. py:function:: stddev_to_fwhm(stddev)