fg_fitsub.py 文件源码

def open_image(infile):
    """
    Open the slice image and return its header and 2D image data.

    NOTE
    ----
    The input slice image may have following dimensions:
    * NAXIS=2: [Y, X]
    * NAXIS=3: [FREQ=1, Y, X]
    * NAXIS=4: [STOKES=1, FREQ=1, Y, X]

    NOTE
    ----
    Only open slice image that has only ONE frequency and ONE Stokes
    parameter.

    Returns
    -------
    header : `~astropy.io.fits.Header`
    image : 2D `~numpy.ndarray`
        The 2D [Y, X] image part of the slice image.
    """
    with fits.open(infile) as f:
        header = f[0].header
        data = f[0].data
    if data.ndim == 2:
        # NAXIS=2: [Y, X]
        image = data
    elif data.ndim == 3 and data.shape[0] == 1:
        # NAXIS=3: [FREQ=1, Y, X]
        image = data[0, :, :]
    elif data.ndim == 4 and data.shape[0] == 1 and data.shape[1] == 1:
        # NAXIS=4: [STOKES=1, FREQ=1, Y, X]
        image = data[0, 0, :, :]
    else:
        raise ValueError("Slice '{0}' has invalid dimensions: {1}".format(
            infile, data.shape))
    return (header, image)