在C++中,浮点型数据(float型)向uchar(unsigned char)强制类型转换是一种什么样的结果?

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#include <iostream>

int main()
{
	uchar a1 = 255;
	int level = 8;
	float scale = level / 256.0;
	
	double b1 = a1*scale;

	uchar b2 = (uchar)b1; //利用强制类型转换浮点型数据b1到unsigned char类型

	uchar b3 = a1*scale; //利用自动转换实现浮点型数据b1到unsigned char类型


	return 0;
}

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#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;

int main()
{
	Mat gray = imread("F:/material/images/2022/2022-06/0-255_level.bmp",0);
	if (gray.empty())
	{
		std::cout << "Error: Could not load image" << std::endl;
		return 0;
	}

	//imshow("Source Image", image);

	int level = 8;
	float scale = level/256.0;

	for (int i = 0; i < gray.rows; i++)
	{
		for (int j = 0; j < gray.cols; j++)
		{
			gray.at<uchar>(i, j) = gray.at<uchar>(i, j) * scale;
		}
	}

	std::cout << gray << std::endl;


	waitKey();
	return(0);
}

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gray.at<uchar>(i, j) = gray.at<uchar>(i, j) * scale;