Python: PS 图像调整--亮度调整

本文用 Python 实现 PS 图像调整中的亮度调整,具体的算法原理和效果可以参考之前的博客:

http://blog.csdn.net/matrix_space/article/details/22991683

import matplotlib.pyplot as plt
from skimage import io file_name='D:/Image Processing/PS Algorithm/4.jpg';
img=io.imread(file_name) Increment = -10.0 img = img * 1.0
I = (img[:, :, 0] + img[:, :, 1] + img[:, :, 2])/3.0 + 0.001 mask_1 = I > 128.0 r = img [:, :, 0]
g = img [:, :, 1]
b = img [:, :, 2] rhs = (r*128.0 - (I - 128.0) * 256.0) / (256.0 - I)
ghs = (g*128.0 - (I - 128.0) * 256.0) / (256.0 - I)
bhs = (b*128.0 - (I - 128.0) * 256.0) / (256.0 - I) rhs = rhs * mask_1 + (r * 128.0 / I) * (1 - mask_1)
ghs = ghs * mask_1 + (g * 128.0 / I) * (1 - mask_1)
bhs = bhs * mask_1 + (b * 128.0 / I) * (1 - mask_1) I_new = I + Increment - 128.0 mask_2 = I_new > 0.0 R_new = rhs + (256.0-rhs) * I_new / 128.0
G_new = ghs + (256.0-ghs) * I_new / 128.0
B_new = bhs + (256.0-bhs) * I_new / 128.0 R_new = R_new * mask_2 + (rhs + rhs * I_new/128.0) * (1-mask_2)
G_new = G_new * mask_2 + (ghs + ghs * I_new/128.0) * (1-mask_2)
B_new = B_new * mask_2 + (bhs + bhs * I_new/128.0) * (1-mask_2) Img_out = img * 1.0 Img_out[:, :, 0] = R_new
Img_out[:, :, 1] = G_new
Img_out[:, :, 2] = B_new Img_out = Img_out/255.0 # 饱和处理
mask_1 = Img_out < 0
mask_2 = Img_out > 1 Img_out = Img_out * (1-mask_1)
Img_out = Img_out * (1-mask_2) + mask_2 plt.figure()
plt.imshow(img/255.0)
plt.axis('off') plt.figure(2)
plt.imshow(Img_out)
plt.axis('off') plt.figure(3)
plt.imshow(I/255.0, plt.cm.gray)
plt.axis('off') plt.show()
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