prtools.pixel_kernel#

pixel_kernel(shape, oversample=1, fftshift=True)[source]#

2D pixel MTF filter kernel

This function returns a normalized 2D sinc function sized to represent the transfer function of an idealized square pixel.

Parameters:

  • shape (int or tuple of int) – Shape of the kernel

  • oversample (float, optional) – Oversampling factor to represent in the kernel. Default is 1.

  • fftshift (bool, optional) – If True (default), the kernel is FFT-shifted before it is returned.

Return type:

ndarray

See also

fftconv(), pixelate(), sinc()

Examples

>>> pixel_mtf = prtools.pixel_kernel((256,256), 1)
>>> plt.imshow(pixel_mtf, cmap='gray', vmin=0)
../_images/prtools-pixel_kernel-1.png

Note this is functionally equivalent to

>>> r = np.fft.fftfreq(256)
>>> c = np.fft.fftfreq(256)
>>> pixel_mtf = np.fft.fftshift(np.abs(prtools.sinc(r, c)))
>>> plt.imshow(pixel_mtf, cmap='gray', vmin=0)
../_images/prtools-pixel_kernel-2.png