Modified fit function to precalculate the distances of pixels to the nearest centroid

reduced_palette.py

class KMeansReducedPalette:
    # ... omitted

    def fit(self, image):
        image_cpy = image.copy()
        self.source_pixels = self._preprocess(image_cpy)
        self.kmeans.fit(self.source_pixels)

        self.centroid_nearest_pixels = []

        for ci in range(self.num_colors):
            pixels_ci = self.source_pixels[self.kmeans.labels_ == ci]
            distances_ci = np.sqrt(np.sum(np.square(
                pixels_ci - self.kmeans.cluster_centers_[ci]), axis=1))
            pixels_ci = pixels_ci[np.argsort(distances_ci)]

            self.centroid_nearest_pixels.append(pixels_ci)

    # ... omitted