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subtract_overscan [2012/11/10 06:22] mjc created |
subtract_overscan [2025/07/03 01:03] (current) onken Update for v2 |
This will tell you about the pywifes.subtract_overscan function... | ** This was the beginning of an effort to document the options available for each step of the pipeline. For an up-to-date and complete implementation of this kind of documentation, please see the [[https://pywifes-pipeline.readthedocs.io/en/latest/index.html| ReadTheDocs site]].** |
| |
| ===== pywifes.subtract_overscan ===== |
| **Purpose:** to subtract overscan from raw WiFeS data. |
| |
| ==== Input Parameters ==== |
| <code> |
| def subtract_overscan(inimg, outimg, |
| data_hdu = 0, |
| detector_regions=None, |
| overscan_regions=None, |
| gain=None, |
| rdnoise=None): |
| </code> |
| |
| * ''inimg'' (//required//) - Input raw WiFeS image, including detector pixels plus overscan pixels. |
| * ''outimg'' (//required//) - Overscan-subtracted data including only 4k x 4k (or appropriate binned size) detector pixels. |
| * ''data_hdu'' - FITS extension in which image data is stored. Default value should be 0, but some data have been stored in data_hdu=1 for unknown reasons. |
| * ''detector_regions'' - Regions of the image data which corresponds to the actual detector. This is a list of length N of lists of length 4, where N is the number of amplifiers reading out the data and each amp is defined by a length 4 list of [xmin, xmax, ymin, ymax] in //unbinned// pixel values. Note these are //not// indexed in Python syntax, but instead are similar to the ''DETSEC'' header keyword syntax. If 'None' default values for given detector epoch are used. |
| * ''overscan_regions'' - Same as ''detector_regions'' but defining overscan regions for each amplifier. If 'None' default values for given detector epoch are used. |
| * ''gain'' - List of gain values of length N, where N is the number of amplifiers. If 'None' default values for given detector epoch are used. |
| * ''rdnoise'' - List of readout noise values of length N, where N is the number of amplifiers. If 'None' default values for given detector epoch are used. |
| |
| ==== Returns ==== |
| * (nothing) |
| |
| ==== Detailed Description ==== |
| This function subtracts overscan values from raw WiFeS frames (''inimg'') and saves output overscan-subtracted data in a new image (''outimg''). For each amplifier, the overscan value is determined as the median value of pixels in the defined overscan region (''overscan_regions''), then subtracted from all pixels values from the detector region for that amplifier (''detector_regions''). Users may input new values for the detector and overscan regions, as well as the gain (''gain'') and readout noise (''rdnoise'') values, but the default values should be determined automatically by calculating the detector epoch. |
| |
| ==== Calling Requirements ==== |
| Input should be raw WiFeS data. |
| |
| ==== Known Limitations ==== |
| None |