def threshold_filter(a_img: ImageImpl, threshold: float) -> ImageImpl:
"""
Given a matrix image representation, apply treshold transformation
and return a binary matrix which follows this transformation:
F(img[i,j]):| max_pixel_value if img[i, j] >= threshold
| 0 else
:param a_img: matrix image representation
:param threshold: float between [0, max pixel value]
:return: transformed matrix
"""
# applies if element wise
a_img.array = a_img.array >= threshold
# transform a boolean matrix binary and scales
a_img.array = a_img.array.astype(int) * MAX_PIXEL_VALUE
return a_img
def median_filter_fast(a_img: ImageImpl, kernel_size: int) -> ImageImpl:
"""
Given an Image instance, apply the median filter using a square kernel of size
kernel_size.
:param a_img: Image instance
:param kernel_size: kernel size int
:return: transformed image
"""
# build kernel
kernel_size = int(kernel_size)
filtered = ndimage.median_filter(a_img.array, size=kernel_size)
a_img.array = filtered
return a_img