Source code for ivadomed.maths

import numpy as np
import os
import scipy

[docs]def rescale_values_array(arr, minv=0.0, maxv=1.0, dtype=np.float32): """Rescale the values of numpy array `arr` to be from `minv` to `maxv`. Args: arr (ndarry): Array whose values will be rescaled. minv (float): Minimum value of the output array. maxv (float): Maximum value of the output array. dtype (type): Cast array to this type before performing the rescaling. """ if dtype is not None: arr = arr.astype(dtype) mina = np.min(arr) maxa = np.max(arr) if mina == maxa: return arr * minv norm = (arr - mina) / (maxa - mina) # normalize the array first return (norm * (maxv - minv)) + minv # rescale by minv and maxv, which is the normalized array by default
[docs]def gaussian_kernel(kernlen=10): """ Create a 2D gaussian kernel with user-defined size. Args: kernlen (int): size of kernel Returns: ndarray: a 2D array of size (kernlen,kernlen) """ x = np.linspace(-1, 1, kernlen + 1) kern1d = np.diff(scipy.stats.norm.cdf(x)) kern2d = np.outer(kern1d, kern1d) return rescale_values_array(kern2d / kern2d.sum())
[docs]def heatmap_generation(image, kernel_size): """ Generate heatmap from image containing sing voxel label using convolution with gaussian kernel Args: image (ndarray): 2D array containing single voxel label kernel_size (int): size of gaussian kernel Returns: ndarray: 2D array heatmap matching the label. """ kernel = gaussian_kernel(kernel_size) map = scipy.signal.convolve(image, kernel, mode='same') return rescale_values_array(map)