Simple image processing based on easyx (C language)

  Because this is the first article, I will first briefly explain how to achieve grayscale image. Graying a picture means converting a color image into a grayscale image. In the RGB model, one pixel of RGB is converted into a transitional color from black to white. The following are two methods for obtaining grayscale images.

1. Find the average value Y of the pixel RGB, and then assign this average value to the three components of R, G, and B.

 2. According to the formula Y = 0.3R + 0.59G + 0.11B, where Y is the gray value. (If you are interested in the source of the specific formula, you can check it)

Before the image is grayed out, here is a program that can check the RGB of a pixel. The function is to display the RGB value of that point by left-clicking the mouse.

#include <graphics.h>
#include <conio.h>
#include <stdio.h>

IMAGE img1;
int imagHight,imagWidth;

int main()
{
	BYTE R;
	BYTE G;
	BYTE B;         //读取像素点RGB
	MOUSEMSG m;		// 定义鼠标消息
	// 读取图片至绘图窗口
	loadimage(&img1, _T("D:\\testh.bmp"));//获取图片
	imagHight = img1.getheight();
	imagWidth = img1.getwidth();          //获取图片高度和宽度
	initgraph(imagWidth,imagHight, SHOWCONSOLE);//设置绘图窗口和图片一样大 并且显示控制台窗口
    putimage(0, 0, &img1);//显示图片
	while(1)
	{
		// 获取一条鼠标消息
		m = GetMouseMsg();
		switch(m.uMsg)
		{
			case WM_LBUTTONDOWN:
				//如果按下鼠标左键 
				R = GetRValue(getpixel(m.x,m.y));
				G = GetGValue(getpixel(m.x,m.y));
				B = GetBValue(getpixel(m.x,m.y));//获取RGB的三个分量值
				printf("X:%3d Y:%3d R:%3d G:%3d B:%3d \n",m.x,m.y,R,G,B);//打印像素点位置和对应的RGB值
				break;

			case WM_RBUTTONUP:
				return 0;	// 按鼠标右键退出程序
		}
	}
	closegraph();
}

Effect picture:

Now I give the first method grayscale program:

#include <graphics.h>
#include <conio.h>
#include <stdio.h>
int Gray[1500][1000]; //存储图像的灰度值数组
IMAGE img1;
int imagHight,imagWidth;
int main()
{
	int i,j;
	// 读取图片至绘图窗口
	loadimage(&img1, _T("D:\\testh.bmp"));
	imagHight = img1.getheight();
	imagWidth = img1.getwidth();
	initgraph(imagWidth,imagHight);
    putimage(0, 0, &img1);
	_getch();
	DWORD* pMem = GetImageBuffer();
	for(i = 0; i <imagHight; i++)
	{
		for(j=0;j<imagWidth;j++)
	  {
	     *pMem = BGR(*pMem);//获取正确的RGB 因为显存与内存rgb存储方式不同
	     Gray[i][j]  = (GetRValue(*pMem)+GetGValue(*pMem)+GetBValue(*pMem))/3;  //取RGB平均值
	     *pMem = RGB(Gray[i][j],Gray[i][j],Gray[i][j]);
	     pMem++;
		} 
	}
	FlushBatchDraw();
	_getch();
	closegraph();
}

Original and renderings:

The second method is to change the

Gray[i][j]  = (GetRValue(*pMem)+GetGValue(*pMem)+GetBValue(*pMem))/3;  //取RGB平均值

Replace with

Gray[i][j]  = GetRValue(*pMem)*0.3+GetGValue(*pMem)*0.59+GetBValue(*pMem)*0.11;

The effect chart is as follows:

 

 

The following are the RGB values ​​of pixels after the first method and the second method respectively.