改变图像部分的亮度和对比度(Changing brightness and contrast of portion of an image)

 给定图像，我想改变图像部分的亮度/对比度。 
 
 我在这里使用一个例子来改变整个图像的亮度/对比度： 
 
RNG rng(cv::getTickCount());
float min_alpha = 0.1;
float max_alpha = 2.0;
float alpha = rng.uniform(min_alpha, max_alpha);
float beta = -2.0;
image.convertTo(new_image, -1, alpha, beta);
 
 有没有办法只在图像的子区域上执行此操作而无需在for循环中迭代整个图像？ 

Given an image, I'd like to change the brightness/contrast on portion of an image. 
 
I'm using an example here to change the brightness/contrast of the whole image:
 
RNG rng(cv::getTickCount());
float min_alpha = 0.1;
float max_alpha = 2.0;
float alpha = rng.uniform(min_alpha, max_alpha);
float beta = -2.0;
image.convertTo(new_image, -1, alpha, beta);
 
Is there a way to do this only on a subregion of an image without having to iterate through the entire image on a for loop?

原文：https://stackoverflow.com/questions/43853560