YUV420相关问题

[baiux]

需要实现的功能：将一张yuv420格式的图片，以（x，y）为圆心，r为半径的圆外所有像素点设置成黑色的。圆内保持不变。
（以下代码新建一个yuv图片，圆内的像素颜色默认，圆外rgb黑色）
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include<iostream>
#include <math.h>

//背景色
#define R 0
#define G 0
#define B 0

#define Y 0.299*R + 0.587*G + 0.114*B
#define U -0.1687*R - 0.3313*G + 0.5*B + 128
#define V 0.5*R - 0.4187*G - 0.0813*B + 128

int main()
{
int width = 256;
int height = 256;

FILE *fp=fopen("F:/yuv/256x256.yuv","wb");

unsigned char *pic = (unsigned char *)malloc(width*height*3/2);

memset(pic, 0, width*height*3/2);

//圆心 半径
double centerHX = 128;
double centerWY = 128;
float radius = 50.0;

for(int i = 0; i < height; i++)
{
for(int j = 0; j < width; j++)
{
float nLength = 0.0;
nLength = sqrt(pow(centerHX - i, 2) + pow(centerWY - j, 2));
if(nLength > radius)
{
pic[i*width + j]=Y;
pic[width*height + i*(width/4) + j/4] = U;
pic[width*height*5/4 + i*(width/4) + j/4] = V;
}
}
}

fwrite(pic,width*height*3/2,1,fp);
fclose(fp);
free(pic);

return 0;
}
编译通过，得到的结果确不对，有没有大神帮忙看下，问题出现在什么地方？？？

[baiux]

[baiux]

引用 2 楼 hefashion0190 的回复:

根据https://en.wikipedia.org/wiki/YUV 公式

size.total = size.width * size.height;
y = yuv[position.y * size.width + position.x];
u = yuv[(position.y / 2) * (size.width / 2) + (position.x / 2) + size.total];
v = yuv[(position.y / 2) * (size.width / 2) + (position.x / 2) + size.total + (size.total / 4)];

代码修改成:

					pic[j * width + i] = Y;
					pic[(j / 2) * (width / 2) + i / 2 + width * height] = U;
					pic[(j / 2) * (width / 2) + i / 2 + width * height + width * height / 4] = V;

非常感谢~不过我还要理解一下

[FoolCarpe]

根据https://en.wikipedia.org/wiki/YUV 公式

size.total = size.width * size.height;
y = yuv[position.y * size.width + position.x];
u = yuv[(position.y / 2) * (size.width / 2) + (position.x / 2) + size.total];
v = yuv[(position.y / 2) * (size.width / 2) + (position.x / 2) + size.total + (size.total / 4)];

代码修改成:

					pic[j * width + i] = Y;
					pic[(j / 2) * (width / 2) + i / 2 + width * height] = U;
					pic[(j / 2) * (width / 2) + i / 2 + width * height + width * height / 4] = V;