我为边缘（Sobel滤波器）编写了CS50 Pset4的以下代码
以下是CS50 Pset4问题描述的链接（仅边缘部分）：https://cs50.harvard.edu/x/2020/psets/4/filter/more/
我编写的代码显示了sobel滤镜图像，但是我的问题仅在于边框像素。
这是我的代码：
// Detect edges
void edges(int height, int width, RGBTRIPLE image[height][width])
{
RGBTRIPLE imgCopy[height][width];
float gxRed;
float gxGreen;
float gxBlue;
float gyRed;
float gyGreen;
float gyBlue;
float gRed;
float gGreen;
float gBlue;
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
imgCopy[h][w].rgbtRed = image[h][w].rgbtRed;
imgCopy[h][w].rgbtGreen = image[h][w].rgbtGreen;
imgCopy[h][w].rgbtBlue = image[h][w].rgbtBlue;
}
}
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
// Top left Corner
if (h == 0 && w == 0)
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = 2 * imgCopy[h][w + 1].rgbtRed + imgCopy[h + 1][w + 1].rgbtRed;
gxGreen = 2 * imgCopy[h][w + 1].rgbtGreen + imgCopy[h + 1][w + 1].rgbtGreen;
gxBlue = 2 * imgCopy[h][w + 1].rgbtBlue + imgCopy[h + 1][w + 1].rgbtBlue;
gyRed = 2 * imgCopy[h + 1][w].rgbtRed + imgCopy[h + 1][w + 1].rgbtRed ;
gyGreen = 2 * imgCopy[h + 1][w].rgbtGreen + imgCopy[h + 1][w + 1].rgbtGreen;
gyBlue = 2 * imgCopy[h + 1][w].rgbtBlue + imgCopy[h + 1][w + 1].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Top-right corner
else if ( h == 0 && w == width - 1 )
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = -2 * imgCopy[h][w - 1].rgbtRed + -1 * imgCopy[h + 1][w - 1].rgbtRed;
gxGreen = -2 * imgCopy[h][w - 1].rgbtGreen + -1 * imgCopy[h + 1][w - 1].rgbtGreen;
gxBlue = -2 * imgCopy[h][w - 1].rgbtBlue + -1 * imgCopy[h + 1][w - 1].rgbtBlue;
gyRed = 2 * imgCopy[h + 1][w].rgbtRed + imgCopy[h + 1][w - 1].rgbtRed;
gyGreen = 2 * imgCopy[h + 1][w].rgbtGreen + imgCopy[h + 1][w - 1].rgbtGreen;
gyBlue = 2 * imgCopy[h + 1][w].rgbtBlue + imgCopy[h + 1][w - 1].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Bottom left corner
else if (h == height - 1 && w == 0 )
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = 1 * imgCopy[h - 1][w + 1].rgbtRed + 2 * imgCopy[h][w + 1].rgbtRed;
gxGreen = 1 * imgCopy[h - 1][w + 1].rgbtGreen + 2 * imgCopy[h][w + 1].rgbtGreen;
gxBlue = 1 * imgCopy[h - 1][w + 1].rgbtBlue + 2 * imgCopy[h][w + 1].rgbtBlue;
gyRed = -1 * imgCopy[h - 1][w + 1].rgbtRed + -2 * imgCopy[h - 1][w].rgbtRed;
gyGreen = -1 * imgCopy[h - 1][w + 1].rgbtGreen + -2 * imgCopy[h - 1][w].rgbtGreen;
gyBlue = -1 * imgCopy[h - 1][w + 1].rgbtBlue + -2 * imgCopy[h - 1][w].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Bottom-right corner
else if ( h == height - 1 && w == width - 1 )
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = -1 * imgCopy[h - 1][w - 1].rgbtRed + -2 * imgCopy[h][w - 1].rgbtRed;
gxGreen = -1 * imgCopy[h - 1][w - 1].rgbtGreen + -2 * imgCopy[h][w - 1].rgbtGreen;
gxBlue = -1 * imgCopy[h - 1][w - 1].rgbtBlue + -2 * imgCopy[h][w - 1].rgbtBlue;
gyRed = -1 * imgCopy[h - 1][w - 1].rgbtRed + -2 * imgCopy[h - 1][w].rgbtRed;
gyGreen = -1 * imgCopy[h - 1][w - 1].rgbtGreen + -2 * imgCopy[h - 1][w].rgbtGreen;
gyBlue = -1 * imgCopy[h - 1][w - 1].rgbtBlue + -2 * imgCopy[h - 1][w].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Top border pixels
else if ( h == 0 && (w > 0 && w < width - 1) )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = -1 * imgCopy[h][w - 1].rgbtRed + 1 * imgCopy[h][w + 1].rgbtRed;
gxGreen = -1 * imgCopy[h][w - 1].rgbtGreen + 1 * imgCopy[h][w + 1].rgbtGreen;
gxBlue = -1 * imgCopy[h][w - 1].rgbtBlue + 1 * imgCopy[h][w + 1].rgbtBlue;
gyRed = 1 * imgCopy[h][w - 1].rgbtRed + 2 * imgCopy[h][w].rgbtRed + 1 * imgCopy[h][w + 1].rgbtRed;
gyGreen = 1 * imgCopy[h][w - 1].rgbtGreen + 2 * imgCopy[h][w].rgbtGreen + 1 * imgCopy[h][w + 1].rgbtGreen;
gyBlue = 1 * imgCopy[h][w - 1].rgbtBlue + 2 * imgCopy[h][w].rgbtBlue + 1 * imgCopy[h][w + 1].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Bottom border pixels
else if ( h == height - 1 && (w > 0 && w < width - 1) )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = -1 * imgCopy[h][w - 1].rgbtRed + 1 * imgCopy[h][w + 1].rgbtRed;
gxGreen = -1 * imgCopy[h][w - 1].rgbtGreen + 1 * imgCopy[h][w + 1].rgbtGreen;
gxBlue = -1 * imgCopy[h][w - 1].rgbtBlue + 1 * imgCopy[h][w + 1].rgbtBlue;
gyRed = -1 * imgCopy[h][w - 1].rgbtRed + -2 * imgCopy[h][w].rgbtRed + -1 * imgCopy[h][w + 1].rgbtRed;
gyGreen = -1 * imgCopy[h][w - 1].rgbtGreen + -2 * imgCopy[h][w].rgbtGreen + -1 * imgCopy[h][w + 1].rgbtGreen;
gyBlue = -1 * imgCopy[h][w - 1].rgbtBlue + -2 * imgCopy[h][w].rgbtBlue + -1 * imgCopy[h][w + 1].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Left-side border pixels
else if ( (h > 0 && h < height - 1) && w == 0 )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = 1 * imgCopy[h - 1][w].rgbtRed + 2 * imgCopy[h][w].rgbtRed + 1 * imgCopy[h + 1][w].rgbtRed;
gxGreen = 1 * imgCopy[h - 1][w].rgbtGreen + 2 * imgCopy[h][w].rgbtGreen + 1 * imgCopy[h + 1][w].rgbtGreen;
gxBlue = 1 * imgCopy[h - 1][w].rgbtBlue + 2 * imgCopy[h][w].rgbtBlue + 1 * imgCopy[h + 1][w].rgbtBlue;
gyRed = -1 * imgCopy[h - 1][w].rgbtRed + 1 * imgCopy[h + 1][w].rgbtRed;
gyGreen = -1 * imgCopy[h - 1][w].rgbtGreen + 1 * imgCopy[h + 1][w].rgbtGreen;
gyBlue = -1 * imgCopy[h - 1][w].rgbtBlue + 1 * imgCopy[h + 1][w].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Right-side border pixels
else if ( (h > 0 && h < height - 1) && w == width - 1 )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = -1 * imgCopy[h - 1][w].rgbtRed + -2 * imgCopy[h][w].rgbtRed + -1 * imgCopy[h + 1][w].rgbtRed;
gxGreen = -1 * imgCopy[h - 1][w].rgbtGreen + -2 * imgCopy[h][w].rgbtGreen + -1 * imgCopy[h + 1][w].rgbtGreen;
gxBlue = -1 * imgCopy[h - 1][w].rgbtBlue + -2 * imgCopy[h][w].rgbtBlue + -1 * imgCopy[h + 1][w].rgbtBlue;
gyRed = -1 * imgCopy[h - 1][w].rgbtRed + 1 * imgCopy[h + 1][w].rgbtRed;
gyGreen = -1 * imgCopy[h - 1][w].rgbtGreen + 1 * imgCopy[h + 1][w].rgbtGreen;
gyBlue = -1 * imgCopy[h - 1][w].rgbtBlue + 1 * imgCopy[h + 1][w].rgbtBlue;
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Middle 3x3 pixels
else
{
gxRed = (float)((-1 * imgCopy[h - 1][w - 1].rgbtRed) + (0 * imgCopy[h - 1][w].rgbtRed) + (1 * imgCopy[h - 1][w + 1].rgbtRed) +
(-2 * imgCopy[h][w - 1].rgbtRed) + (0 * imgCopy[h][w].rgbtRed) + (2 * imgCopy[h][w + 1].rgbtRed) +
(-1 * imgCopy[h + 1][w - 1].rgbtRed) + (0 * imgCopy[h + 1][w].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed));
gxGreen = (float)((-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (0 * imgCopy[h - 1][w].rgbtGreen) + (1 * imgCopy[h - 1][w + 1].rgbtGreen) +
(-2 * imgCopy[h][w - 1].rgbtGreen) + (0 * imgCopy[h][w].rgbtGreen) + (2 * imgCopy[h][w + 1].rgbtGreen) +
(-1 * imgCopy[h + 1][w - 1].rgbtGreen) + (0 * imgCopy[h + 1][w].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen));
gxBlue = (float)((-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (0 * imgCopy[h - 1][w].rgbtBlue) + (1 * imgCopy[h - 1][w + 1].rgbtBlue) +
(-2 * imgCopy[h][w - 1].rgbtBlue) + (0 * imgCopy[h][w].rgbtBlue) + (2 * imgCopy[h][w + 1].rgbtBlue) +
(-1 * imgCopy[h + 1][w - 1].rgbtBlue) + (0 * imgCopy[h + 1][w].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue));
gyRed = (float)((-1 * imgCopy[h - 1][w - 1].rgbtRed) + (-2 * imgCopy[h - 1][w].rgbtRed) + (-1 * imgCopy[h - 1][w + 1].rgbtRed) +
(0 * imgCopy[h][w - 1].rgbtRed) + (0 * imgCopy[h][w].rgbtRed) + (0 * imgCopy[h][w + 1].rgbtRed) +
(1 * imgCopy[h + 1][w - 1].rgbtRed) + (2 * imgCopy[h + 1][w].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed));
gyGreen = (float)((-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (-2 * imgCopy[h - 1][w].rgbtGreen) + (-1 * imgCopy[h - 1][w + 1].rgbtGreen) +
(0 * imgCopy[h][w - 1].rgbtGreen) + (0 * imgCopy[h][w].rgbtGreen) + (0 * imgCopy[h][w + 1].rgbtGreen) +
(1 * imgCopy[h + 1][w - 1].rgbtGreen) + (2 * imgCopy[h + 1][w].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen));
gyBlue = (float)((-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (-2 * imgCopy[h - 1][w].rgbtBlue) + (-1 * imgCopy[h - 1][w + 1].rgbtBlue) +
(0 * imgCopy[h][w - 1].rgbtBlue) + (0 * imgCopy[h][w].rgbtBlue) + (0 * imgCopy[h][w + 1].rgbtBlue) +
(1 * imgCopy[h + 1][w - 1].rgbtBlue) + (2 * imgCopy[h + 1][w].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue));
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if(gRed > 255)
{
gRed = 255;
}
if(gGreen > 255)
{
gGreen = 255;
}
if(gBlue > 255)
{
gBlue = 255;
}
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
}
}
return;
}
这些是我运行（check50）检查我的代码时收到的错误消息：
:)边缘正确过滤了中间像素（此部分正确）
:(边缘正确过滤边缘上的像素 应该是“ 213228255 \ n”，而不是“ 57103174 \ n”
:)边缘正确过滤了角落中的像素。 （这部分是正确的）
:(边缘正确过滤3x3图像 应该是“ 76117255 \ n21 ...”，而不是“ 76117255 \ n57 ...”
:(边缘正确过滤4x4图像 应该是“ 76117255 \ n21 ...”，而不是“ 76117255 \ n57 ...”
答案 0 :(得分：0)
更新：我在代码中添加了单独的功能，以消除重复的代码并使代码更短。
好的，我解决了。长时间盯着它。我注意到边界像素应包含Gx矩阵的2行或2列（而不只是Gx，Gy矩阵的1行或1列）。在那个3x3矩阵中，您将得到一个假想的3像素，该像素等于零，因为它在该图像的边界之外。
无论如何，这里还是我完整的正确代码，以防万一有人也为此代码而苦恼。
还有其他人解决了这个问题，但是他们的代码对我来说还不够清楚。遗憾的是，由于我的帐户是新帐户，我没有足够的声誉积分来评论该帖子并向他们提出一些问题。
void findG();
float gxRed, gxGreen, gxBlue;
float gyRed, gyGreen, gyBlue;
float gRed, gGreen, gBlue;
// Detect edges
void edges(int height, int width, RGBTRIPLE image[height][width])
{
RGBTRIPLE imgCopy[height][width];
// Making a copy of image
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
imgCopy[h][w].rgbtRed = image[h][w].rgbtRed;
imgCopy[h][w].rgbtGreen = image[h][w].rgbtGreen;
imgCopy[h][w].rgbtBlue = image[h][w].rgbtBlue;
}
}
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width; w++)
{
// Top left Corner
if (h == 0 && w == 0)
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = 2 * imgCopy[h][w + 1].rgbtRed + imgCopy[h + 1][w + 1].rgbtRed;
gxGreen = 2 * imgCopy[h][w + 1].rgbtGreen + imgCopy[h + 1][w + 1].rgbtGreen;
gxBlue = 2 * imgCopy[h][w + 1].rgbtBlue + imgCopy[h + 1][w + 1].rgbtBlue;
gyRed = 2 * imgCopy[h + 1][w].rgbtRed + imgCopy[h + 1][w + 1].rgbtRed ;
gyGreen = 2 * imgCopy[h + 1][w].rgbtGreen + imgCopy[h + 1][w + 1].rgbtGreen;
gyBlue = 2 * imgCopy[h + 1][w].rgbtBlue + imgCopy[h + 1][w + 1].rgbtBlue;
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Top-right corner
else if ( h == 0 && w == width - 1 )
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = -2 * imgCopy[h][w - 1].rgbtRed + -1 * imgCopy[h + 1][w - 1].rgbtRed;
gxGreen = -2 * imgCopy[h][w - 1].rgbtGreen + -1 * imgCopy[h + 1][w - 1].rgbtGreen;
gxBlue = -2 * imgCopy[h][w - 1].rgbtBlue + -1 * imgCopy[h + 1][w - 1].rgbtBlue;
gyRed = 2 * imgCopy[h + 1][w].rgbtRed + imgCopy[h + 1][w - 1].rgbtRed;
gyGreen = 2 * imgCopy[h + 1][w].rgbtGreen + imgCopy[h + 1][w - 1].rgbtGreen;
gyBlue = 2 * imgCopy[h + 1][w].rgbtBlue + imgCopy[h + 1][w - 1].rgbtBlue;
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Bottom left corner
else if (h == height - 1 && w == 0 )
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = 1 * imgCopy[h - 1][w + 1].rgbtRed + 2 * imgCopy[h][w + 1].rgbtRed;
gxGreen = 1 * imgCopy[h - 1][w + 1].rgbtGreen + 2 * imgCopy[h][w + 1].rgbtGreen;
gxBlue = 1 * imgCopy[h - 1][w + 1].rgbtBlue + 2 * imgCopy[h][w + 1].rgbtBlue;
gyRed = -1 * imgCopy[h - 1][w + 1].rgbtRed + -2 * imgCopy[h - 1][w].rgbtRed;
gyGreen = -1 * imgCopy[h - 1][w + 1].rgbtGreen + -2 * imgCopy[h - 1][w].rgbtGreen;
gyBlue = -1 * imgCopy[h - 1][w + 1].rgbtBlue + -2 * imgCopy[h - 1][w].rgbtBlue;
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Bottom-right corner
else if ( h == height - 1 && w == width - 1 )
{
// For Gx and Gy values imagine a 3x3 matrix at the corner and any pixel outside the corner is considered to be equal zero
//(The corner pixels does not equal 0 you treat the corner pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = -1 * imgCopy[h - 1][w - 1].rgbtRed + -2 * imgCopy[h][w - 1].rgbtRed;
gxGreen = -1 * imgCopy[h - 1][w - 1].rgbtGreen + -2 * imgCopy[h][w - 1].rgbtGreen;
gxBlue = -1 * imgCopy[h - 1][w - 1].rgbtBlue + -2 * imgCopy[h][w - 1].rgbtBlue;
gyRed = -1 * imgCopy[h - 1][w - 1].rgbtRed + -2 * imgCopy[h - 1][w].rgbtRed;
gyGreen = -1 * imgCopy[h - 1][w - 1].rgbtGreen + -2 * imgCopy[h - 1][w].rgbtGreen;
gyBlue = -1 * imgCopy[h - 1][w - 1].rgbtBlue + -2 * imgCopy[h - 1][w].rgbtBlue;
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Top border pixels
else if ( h == 0 && (w > 0 && w < width - 1) )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero.
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = (-2 * imgCopy[h][w - 1].rgbtRed) + (2 * imgCopy[h][w + 1].rgbtRed) + (-1 * imgCopy[h + 1][w - 1].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed) ;
gxGreen = (-2 * imgCopy[h][w - 1].rgbtGreen) + (2 * imgCopy[h][w + 1].rgbtGreen) + (-1 * imgCopy[h + 1][w - 1].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen) ;
gxBlue = (-2 * imgCopy[h][w - 1].rgbtBlue) + (2 * imgCopy[h][w + 1].rgbtBlue) + (-1 * imgCopy[h + 1][w - 1].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue) ;
gyRed = (1 * imgCopy[h + 1][w - 1].rgbtRed) + (2 * imgCopy[h + 1][w].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed);
gyGreen = (1 * imgCopy[h + 1][w - 1].rgbtGreen) + (2 * imgCopy[h + 1][w].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen);
gyBlue = (1 * imgCopy[h + 1][w - 1].rgbtBlue) + (2 * imgCopy[h + 1][w].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue);
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Bottom border pixels
else if ( h == height - 1 && (w > 0 && w < width - 1) )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = (-2 * imgCopy[h][w - 1].rgbtRed) + (2 * imgCopy[h][w + 1].rgbtRed) + (-1 * imgCopy[h - 1][w - 1].rgbtRed) + (1 * imgCopy[h - 1][w + 1].rgbtRed) ;
gxGreen = (-2 * imgCopy[h][w - 1].rgbtGreen) + (2 * imgCopy[h][w + 1].rgbtGreen) + (-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (1 * imgCopy[h - 1][w + 1].rgbtGreen) ;
gxBlue = (-2 * imgCopy[h][w - 1].rgbtBlue) + (2 * imgCopy[h][w + 1].rgbtBlue) + (-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (1 * imgCopy[h - 1][w + 1].rgbtBlue) ;
gyRed = (-1 * imgCopy[h - 1][w - 1].rgbtRed) + (-2 * imgCopy[h - 1][w].rgbtRed) + (-1 * imgCopy[h - 1][w + 1].rgbtRed);
gyGreen = (-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (-2 * imgCopy[h - 1][w].rgbtGreen) + (-1 * imgCopy[h - 1][w + 1].rgbtGreen);
gyBlue = (-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (-2 * imgCopy[h - 1][w].rgbtBlue) + (-1 * imgCopy[h - 1][w + 1].rgbtBlue);
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Left-side border pixels
else if ( (h > 0 && h < height - 1) && w == 0 )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = (1 * imgCopy[h - 1][w + 1].rgbtRed) + (2 * imgCopy[h][w + 1].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed);
gxGreen = (1 * imgCopy[h - 1][w + 1].rgbtGreen) + (2 * imgCopy[h][w + 1].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen);
gxBlue = (1 * imgCopy[h - 1][w + 1].rgbtBlue) + (2 * imgCopy[h][w + 1].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue);
gyRed = (-2 * imgCopy[h - 1][w].rgbtRed) + (2 * imgCopy[h + 1][w].rgbtRed) + (-1 * imgCopy[h - 1][w + 1].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed);
gyGreen = (-2 * imgCopy[h - 1][w].rgbtGreen) + (2 * imgCopy[h + 1][w].rgbtGreen) + (-1 * imgCopy[h - 1][w + 1].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen);
gyBlue = (-2 * imgCopy[h - 1][w].rgbtBlue) + (2 * imgCopy[h + 1][w].rgbtBlue) + (-1 * imgCopy[h - 1][w + 1].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue);
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Right-side border pixels
else if ( (h > 0 && h < height - 1) && w == width - 1 )
{
// For Gx and Gy values imagine a 3x3 matrix at the border and any pixel outside the border is considered to be equal zero
//(The border pixels does not equal 0 you treat the border pixel as a 3x3 matrix same as the middle pixels and get the Gx and Gy values for them)
gxRed = (-1 * imgCopy[h - 1][w - 1].rgbtRed) + (-2 * imgCopy[h][w - 1].rgbtRed) + (-1 * imgCopy[h + 1][w - 1].rgbtRed);
gxGreen = (-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (-2 * imgCopy[h][w - 1].rgbtGreen) + (-1 * imgCopy[h + 1][w - 1].rgbtGreen);
gxBlue = (-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (-2 * imgCopy[h][w - 1].rgbtBlue) + (-1 * imgCopy[h + 1][w - 1].rgbtBlue);
gyRed = (-1 * imgCopy[h - 1][w - 1].rgbtRed) + (-2 * imgCopy[h - 1][w].rgbtRed) + (1 * imgCopy[h + 1][w - 1].rgbtRed) + (2 * imgCopy[h + 1][w].rgbtRed);
gyGreen = (-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (-2 * imgCopy[h - 1][w].rgbtGreen) + (1 * imgCopy[h + 1][w - 1].rgbtGreen) + (2 * imgCopy[h + 1][w].rgbtGreen);
gyBlue = (-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (-2 * imgCopy[h - 1][w].rgbtBlue) + (1 * imgCopy[h + 1][w - 1].rgbtBlue) + (2 * imgCopy[h + 1][w].rgbtBlue);
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
// Middle 3x3 pixels
else
{
gxRed = (float)((-1 * imgCopy[h - 1][w - 1].rgbtRed) + (1 * imgCopy[h - 1][w + 1].rgbtRed) +
(-2 * imgCopy[h][w - 1].rgbtRed) + (2 * imgCopy[h][w + 1].rgbtRed) +
(-1 * imgCopy[h + 1][w - 1].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed));
gxGreen = (float)((-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (1 * imgCopy[h - 1][w + 1].rgbtGreen) +
(-2 * imgCopy[h][w - 1].rgbtGreen) + (2 * imgCopy[h][w + 1].rgbtGreen) +
(-1 * imgCopy[h + 1][w - 1].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen));
gxBlue = (float)((-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (1 * imgCopy[h - 1][w + 1].rgbtBlue) +
(-2 * imgCopy[h][w - 1].rgbtBlue) + (2 * imgCopy[h][w + 1].rgbtBlue) +
(-1 * imgCopy[h + 1][w - 1].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue));
gyRed = (float)((-1 * imgCopy[h - 1][w - 1].rgbtRed) + (-2 * imgCopy[h - 1][w].rgbtRed) + (-1 * imgCopy[h - 1][w + 1].rgbtRed) +
(1 * imgCopy[h + 1][w - 1].rgbtRed) + (2 * imgCopy[h + 1][w].rgbtRed) + (1 * imgCopy[h + 1][w + 1].rgbtRed));
gyGreen = (float)((-1 * imgCopy[h - 1][w - 1].rgbtGreen) + (-2 * imgCopy[h - 1][w].rgbtGreen) + (-1 * imgCopy[h - 1][w + 1].rgbtGreen) +
(1 * imgCopy[h + 1][w - 1].rgbtGreen) + (2 * imgCopy[h + 1][w].rgbtGreen) + (1 * imgCopy[h + 1][w + 1].rgbtGreen));
gyBlue = (float)((-1 * imgCopy[h - 1][w - 1].rgbtBlue) + (-2 * imgCopy[h - 1][w].rgbtBlue) + (-1 * imgCopy[h - 1][w + 1].rgbtBlue) +
(1 * imgCopy[h + 1][w - 1].rgbtBlue) + (2 * imgCopy[h + 1][w].rgbtBlue) + (1 * imgCopy[h + 1][w + 1].rgbtBlue));
findG(h,w);
image[h][w].rgbtRed = gRed;
image[h][w].rgbtGreen = gGreen;
image[h][w].rgbtBlue = gBlue;
}
}
}
return;
}
void findG(int h ,int w)
{
gRed = sqrt((gxRed * gxRed) + (gyRed * gyRed));
gGreen = sqrt((gxGreen * gxGreen) + (gyGreen * gyGreen));
gBlue = sqrt((gxBlue * gxBlue) + (gyBlue * gyBlue));
gRed = round(gRed);
gGreen = round(gGreen);
gBlue = round(gBlue);
if (gRed > 255)
{
gRed = 255;
}
if (gGreen > 255)
{
gGreen = 255;
}
if (gBlue > 255)
{
gBlue = 255;
}
return;
}
以下是运行时的结果（检查50）：
:)边缘正确过滤了中间像素
:)边缘正确过滤边缘上的像素
:)边缘正确过滤了角落的像素
:)边缘可以正确过滤3x3图像
:)边缘可以正确过滤4x4图像