Crop Step Function

[ell-bogat]

Describe your changes

Adds a new step function l3_to_l4.crop() to crop data and update relevant header values.

• Can accept any data level.
• Can handle 2D or 3D Image data, but if data is 3D we assume it is a stack of images and only crop the last two indices.
• kwarg sizexy is the desired data shape in xy order. Currently required to be even. If a single value is provided we assume a square data shape. Defaults to 60 (a little bigger than the dark hole region).
• kwarg centerxy is the pixel location to center the cropping on, should be the intersection of 4 pixels since we want an even data shape. Raises a warning if the provided center is not a half-integer, and centers on the nearest pixel intersection. Defaults to the star location in the extension header ("STARLOCX"/"STARLOCY") and will raise an exception if no value is provided but the location is missing from the header.
• Updates axis sizes and various pixel locations that may be in the headers, but we'll need to make sure this function gets updated if new relevant header keywords get added.

Possible future additions (low priority):

• Add option to crop to an odd data shape centered on a pixel
• Add capability to handle regions outside the FOV by padding with nans.

Example:
Input dataset with a square "PSF" at the position of "STARLOCX/Y" in the header:

cropped_dataset = crop(input_dataset) automatically crops to 60 pixels around "STARLOCX/Y":

Type of change

• New feature (non-breaking change which adds functionality)

Reference any relevant issues (don't forget the #)

Issue #261: Need a step function to crop data

Checklist before requesting a review

• I have linted my code
• I have verified that all unit tests pass in a clean environment and added new unit tests, as needed
• I have verified that all docstrings are properly formatted and added new documentation, as needed

[maxwellmb]

Some quick change requests/comments

[maxwellmb]

Thanks for the changes!

[maxwellmb]

I think we should make use the FSAMNAME keyword to define the crop region. I'm not sure what the header keyword value we want is, but the definition is "easily understand PAM configuration.", as seen on this page.