July 2019
Intermediate to advanced
365 pages
8h 13m
Chinese
Content preview from Python机器学习手册：从数据预处理到深度学习
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138
｜
第
8
章
图像处理
8.7
提升对比度
问题描述
增强图像中像素间的对比度。
解决方案
直方图均衡是一种图像处理方法，它可以使图像中的物体和形状更加突出。对于灰度图
像，可以直接在图像上应用
OpenCV
的
equalizeHist
：
#
加载库
import cv2
import numpy as np
from matplotlib import pyplot as plt
#
加载图像
image = cv2.imread("images/plane_256x256.jpg", cv2.IMREAD_GRAYSCALE)
#
增强图像
image_enhanced = cv2.equalizeHist(image)
#
显示图像
plt.imshow(image_enhanced, cmap="gray"), plt.axis("off")
plt.show()
8.7
提升对比度
｜
139
但是如果对彩色图像进行增强操作，首先需要将其转换为
YUV
格式。其中
Y
表示亮度，
U
和
V
表示颜色。转换后，可以将
equalizeHist
方法应用于此图像，然后将其转换回
BGR
或
RGB
格式 ：
#
加载图像
image_bgr = cv2.imread("images/plane.jpg") ...
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