图像压缩后得到的灰度图

Question

我正在使用 K 均值聚类算法执行图像压缩。压缩后得到的图像是灰度图像，如何得到与原始图像质量相当的彩色图像？

import os
from skimage import io
from sklearn.cluster import  MiniBatchKMeans
import numpy as np

algorithm = "full"
for f in os.listdir('.'):
    if f.endswith('.png'):
        image = io.imread(f)
        rows = image.shape[0]
        cols = image.shape[1]

        image = image.reshape(image.shape[0] * image.shape[1], image.shape[2])
        kmeans = MiniBatchKMeans(n_clusters=128, n_init=10, max_iter=200)
        kmeans.fit(image)

        clusters = np.asarray(kmeans.cluster_centers_, dtype=np.uint8)
        labels = np.asarray(kmeans.labels_, dtype=np.uint8)
        labels = labels.reshape(rows, cols);

        #  np.save('codebook'+f+'.npy', clusters)
        io.imsave('compressed_' + f , labels);

Answer 1

您可以通过 Numpy 的 broadcasting 高效地将 labels 转换为彩色图像 clusters[labels]。

演示

from skimage import io
from sklearn.cluster import MiniBatchKMeans
import numpy as np
import matplotlib.pyplot as plt

image = io.imread('https://i.stack.imgur.com/LkU1i.jpg')
rows = image.shape[0]
cols = image.shape[1]

pixels = image.reshape(image.shape[0] * image.shape[1], image.shape[2])
kmeans = MiniBatchKMeans(n_clusters=128, n_init=10, max_iter=200)
kmeans.fit(pixels)

clusters = np.asarray(kmeans.cluster_centers_, dtype=np.uint8)
labels = np.asarray(kmeans.labels_, dtype=np.uint8).reshape(rows, cols)

colored = clusters[labels]

d = {'Image': image, 'Labels': labels, 'Colored': colored}

fig, ax = plt.subplots(1, 3)

for i, name in enumerate(d):
    cmap = 'gray' if d[name].ndim == 2 else 'jet'
    ax[i].imshow(d[name], cmap=cmap)
    ax[i].axis('off')
    ax[i].set_title(name)

plt.show(fig)

图像压缩后得到的灰度图

Grayscale image obtained after image compression

python

image-compression

k-means

lossy-compression

scikit-image

演示