視覺影像比較

當執行影像處理任務 (例如曝光處理、濾波和還原) 時，影像比較特別有用。

此範例示範如何輕鬆地使用各種方法比較兩個影像。

import matplotlib.pyplot as plt
from matplotlib.gridspec import GridSpec

from skimage import data, transform, exposure
from skimage.util import compare_images


img1 = data.coins()
img1_equalized = exposure.equalize_hist(img1)
img2 = transform.rotate(img1, 2)


comp_equalized = compare_images(img1, img1_equalized, method='checkerboard')
diff_rotated = compare_images(img1, img2, method='diff')
blend_rotated = compare_images(img1, img2, method='blend')

棋盤格

checkerboard 方法會交替來自第一個和第二個影像的圖塊。

fig = plt.figure(figsize=(8, 9))

gs = GridSpec(3, 2)
ax0 = fig.add_subplot(gs[0, 0])
ax1 = fig.add_subplot(gs[0, 1])
ax2 = fig.add_subplot(gs[1:, :])

ax0.imshow(img1, cmap='gray')
ax0.set_title('Original')
ax1.imshow(img1_equalized, cmap='gray')
ax1.set_title('Equalized')
ax2.imshow(comp_equalized, cmap='gray')
ax2.set_title('Checkerboard comparison')

for a in (ax0, ax1, ax2):
    a.set_axis_off()

fig.tight_layout()

差異

diff 方法會計算兩個影像之間的絕對差異。

fig = plt.figure(figsize=(8, 9))

gs = GridSpec(3, 2)
ax0 = fig.add_subplot(gs[0, 0])
ax1 = fig.add_subplot(gs[0, 1])
ax2 = fig.add_subplot(gs[1:, :])

ax0.imshow(img1, cmap='gray')
ax0.set_title('Original')
ax1.imshow(img2, cmap='gray')
ax1.set_title('Rotated')
ax2.imshow(diff_rotated, cmap='gray')
ax2.set_title('Diff comparison')

for a in (ax0, ax1, ax2):
    a.set_axis_off()

fig.tight_layout()

混合

blend 是兩個影像平均的結果。

fig = plt.figure(figsize=(8, 9))

gs = GridSpec(3, 2)
ax0 = fig.add_subplot(gs[0, 0])
ax1 = fig.add_subplot(gs[0, 1])
ax2 = fig.add_subplot(gs[1:, :])

ax0.imshow(img1, cmap='gray')
ax0.set_title('Original')
ax1.imshow(img2, cmap='gray')
ax1.set_title('Rotated')
ax2.imshow(blend_rotated, cmap='gray')
ax2.set_title('Blend comparison')

for a in (ax0, ax1, ax2):
    a.set_axis_off()

fig.tight_layout()

plt.show()