RGB图像任意角度旋转

最新推荐文章于 2025-06-05 09:11:47 发布

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最新推荐文章于 2025-06-05 09:11:47 发布

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分类专栏： c++ 图像处理(opengl) 文章标签： rgb c++ 任意角度旋转

本文链接：https://blog.youkuaiyun.com/u011270282/article/details/41483905

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本文介绍了RGB图像在C++中进行任意角度旋转的数学推导及代码实现，包括坐标变换公式、边界点计算和旋转后的图像尺寸调整。提供了一个名为`Rotate`的函数，用于完成图像旋转操作。

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推导：

x = r cos(b);

y = r sin(b); _ _ _ _ _ _ _ _ (1)

x’ = r cos(a+b);

y’ = r sin(a+b); _ _ _ _ _ _ _ _ (2)

cos(a+b) = cos(a)cos(b)-sin(a)sin(b);

sin(a+b) = sin(a)cos(b)+cos(a)sin(b); _ _ _ _ _ _ _ _ (3)

将（3）代入（2）：

x’ = r cos(a)cos(b) - r sin(a)sin(b);

y’ = r sin(a)cos(b) + r cos(a)sin(b); _ _ _ _ _ _ _ _ (4)

将（1）代入（4）：

x’ = x cos(a) - y sin(a);

y’ = x sin(a) + y cos(a); _ _ _ _ _ _ _ _ (5)

根据（5）求对应源坐标：

x = x’ cos(a) + y’ sin(a);

y = -x’ sin(a) + y’ cos(a);

代码：

BYTE* Rotate(BYTE* pSrc,BYTE* pDest,int nWidth,int nHeight,int& nResW,int& nResH,double dAngel)
{
double cos_angle = cos(dAngel);
double sin_angle = sin(dAngel);

POINT p1={0,0};
POINT p2={nWidth,0};
POINT p3={0,nHeight};
POINT p4={nWidth,nHeight};
POINTF newP1,newP2,newP3,newP4, leftTop, rightTop, leftBottom, rightBottom;

newP1.x = (float)p1.x;
newP1.y = (float)p1.y;
newP2.x = (float)(p2.x*cos_angle - p2.y*sin_angle);
newP2.y = (float)(p2.x*sin_angle + p2.y*cos_angle);
newP3.x = (float)(p3.x*cos_angle - p3.y*sin_angle);
newP3.y = (float)(p3.x*sin_angle + p3.y*cos_angle);
newP4.x = (float)(p4.x*cos_angle - p4.y*sin_angle);
newP4.y = (float)(p4.x*sin_angle + p4.y*cos_angle);

leftTop.x = min(min(newP1.x,newP2.x),min(newP3.x,newP4.x));
leftTop.y = min(min(newP1.y,newP2.y),min(newP3.y,newP4.y));
rightBottom.x = max(max(newP1.x,newP2.x),max(newP3.x,newP4.x));
rightBottom.y = max(max(newP1.y,newP2.y),max(newP3.y,newP4.y));
leftBottom.x = leftTop.x;
leftBottom.y = rightBottom.y;
rightTop.x = rightBottom.x;
rightTop.y = leftTop.y;

nResW = (int) floor(0.5f + rightTop.x - leftTop.x);
nResH= (int) floor(0.5f + leftBottom.y - leftTop.y);

BYTE* pRet = new BYTE[nResW*nResH*3];

int nOldStride = nWidth*3;
int nNewStride = nResW*3;

int x,y,newX,newY,oldX,oldY;

for (y = (int)leftTop.y, newY = 0; y<=(int)leftBottom.y; y++,newY++)
{
int nNewPosY = newY*nNewStride;
for (x = (int)leftTop.x, newX = 0; x<=(int)rightTop.x; x++,newX++)
{
oldX = (int)(x*cos_angle + y*sin_angle + 0.5);
oldY = (int)(y*cos_angle - x*sin_angle + 0.5);

if(IsPointInside(oldX,oldY,nWidth,nHeight))
{
int nNewPosX = newX*3;

int nOldPos = oldY*nOldStride + oldX*3;

if (nOldPos >= 0)
{
pRet[nNewPosY + nNewPosX] = pSrc[nOldPos];
pRet[nNewPosY + nNewPosX + 1] = pSrc[nOldPos + 1];
pRet[nNewPosY + nNewPosX + 2] = pSrc[nOldPos + 2];
}
}

}
}
return pRet;
}