Bilateral Filter

实验报告

专业：软件工程________
姓名：陈锰____________
学号：3170105197______
日期：2018/12/16_______

课程名称：____图像信息处理___ 指导老师：____宋明黎____成绩：__________________
实验名称：___Bilateral Filter____

一、实验目的和要求

学习和认识图像的滤波和增强原理，加深对图像离散值中的一阶微分和二阶微分原理的理解，通过实践操作熟悉均值滤波、中值滤波、高斯滤波和拉普拉斯变换方法，进一步掌握空间滤波原理和技术。

二、实验内容和原理

三、实验结果

1.结果分析

Hermione_former

Hermione_later

2.源代码

#include
#include
#include
#define SIZE 5              //Define the size for the mask
#define OFFSET (SIZE / 2)   //Define the offset of the mask
#define SIGMA_S 20          //Define sigma_s for space domain
#define SIGMA_R 10          //Define sigma_r for range domain

double Wbf(double ** mask_s, double ** mask_r);  //Caculate the normalization coefficient
double ** Mask_S(double **mask, double sigma_s);  //Generate mask_s for space domain
double ** Mask_R(double **mask, double sigma_r, int x, int y);  //Generate mask_r for range domain
void BilateralFilter(CImage image, double ** mask_s, double ** mask_r);  //Implementation of Bilateral Filter
int main()
{
    CImage image;
    image.Load("testBMP.bmp");
    double ** mask_s = NULL, **mask_r = NULL;
    //Initialize mask_s, mask_r
    mask_s = (double**)malloc(SIZE * sizeof(double*));
    mask_r = (double**)malloc(SIZE * sizeof(double*));
    for (int i = 0; i < SIZE; i++)
    {
        mask_s[i] = (double*)malloc(SIZE * sizeof(double));
        mask_r[i] = (double*)malloc(SIZE * sizeof(double));
    }
    BilateralFilter(image, mask_s, mask_r);
    getchar();
    return 0;
}


double Gaussian(double sigma, double x)
{
    //Gaussian function without the constant coefficient
    return exp(-0.5 * x * x / (sigma * sigma));
}

double ** Mask_S(double **mask, double sigma_s)
{
    //Mask_S is obtained based on the position of pixels around the key pixel
    //Horizontal and vertical distance are considered alike
    for (int i = -OFFSET; i <= OFFSET; i++)
        for (int j = -OFFSET; j <= OFFSET; j++)
            mask[i + OFFSET][j + OFFSET] = Gaussian(sigma_s, i) * Gaussian(sigma_s, j);
    return mask;
}
double ** Mask_R(double **mask, double sigma_r, int x, int y)
{
    CImage Bmp;
    COLORREF color1, color2;
    int r, g, b;
    Bmp.Load("testBMP.bmp");
    //Get RGB value of the key piexl
    color1 = Bmp.GetPixel(x, y);
    r = GetRValue(color1);
    g = GetGValue(color1);
    b = GetBValue(color1);
    for (int i = -OFFSET; i <= OFFSET; i++)
        for (int j = -OFFSET; j <= OFFSET; j++)
        {
            //R,G,B channels are considered based on the difference value btween key pixel and others
            color2 = Bmp.GetPixel(x + i, y + j);
            //Caculate the difference value btween key pixel and others respectively
            int dR = r - GetRValue(color2);
            int dG = g - GetGValue(color2);
            int dB = b - GetBValue(color2);
            //Combine the effect of the three channels and mask_r is acquired
            mask[i + OFFSET][j + OFFSET] = Gaussian(sigma_r, dR) * Gaussian(sigma_r, dG) * Gaussian(sigma_r, dB);
        }
    return mask;
}

double Wbf(double ** mask_s, double ** mask_r)
{
    double wbf = 0;
    //Multiple each pair of elements in this two masks, the sum them up
    for (int i = 0; i < SIZE; i++)
        for (int j = 0; j < SIZE; j++)
            wbf += mask_s[i][j] * mask_r[i][j];
    return wbf;
}

//Implementation of weighted bilateral filter
void BilateralFilter(CImage image, double ** mask_s, double ** mask_r)
{
    printf("Waite a minute...");
    CImage bmp = image;
    //Get mask_s invoking Mask_S
    mask_s = Mask_S(mask_s, SIGMA_S);
    for (int i = OFFSET; i < bmp.GetWidth() - OFFSET; i++)
    {
        for (int j = OFFSET; j < bmp.GetHeight() - OFFSET; j++)
        {
            COLORREF color;
            double r = 0, g = 0, b = 0;
            //Get real time mask_r invoking Mask_R
            mask_r = Mask_R(mask_r, SIGMA_R, i, j);
            double w = Wbf(mask_s, mask_r);
            //Caculate the value of goal pixel with mask_s and mask_r
            for (int pi = -OFFSET; pi <= OFFSET; pi++)
                for (int pj = -OFFSET; pj <= OFFSET; pj++)
                {
                    color = image.GetPixel(i + pi, j + pj);
                    double k = mask_s[OFFSET + pi][OFFSET + pj] * mask_r[OFFSET + pi][OFFSET + pj];
                    r += k * GetRValue(color);
                    g += k * GetGValue(color);
                    b += k * GetBValue(color);
                }
            //Rearrange the value of RGB avoid overflow
            r = (int)(r / w + 0.5);
            g = (int)(g / w + 0.5);
            b = (int)(b / w + 0.5);
            r = r > 255 ? 255 : r;
            r = r < 0 ? 0 : r;
            g = g > 255 ? 255 : g;
            g = g < 0 ? 0 : g;
            b = b > 255 ? 255 : b;
            b = b < 0 ? 0 : b;
            //Set pixel
            bmp.SetPixelRGB(i, j, (BYTE)r, (BYTE)g, (BYTE)b);
        }
    }
    //Save the new image and a success prompt will be given on the console
    bmp.Save("BilateralFilter.bmp");
    printf("\nBilateral Filter Successful!\n");
}

List * GenerateGraph(int *hashTable, List *graph, int N)
{
int i, j;
List * p;
graph = (List )calloc(N, sizeof(struct list));
for(i = 0; i < N; i++)
if(hashTable[i] >= 0)
{
graph[i] = (List)malloc(sizeof(struct list));
graph[i]->Name = i;
graph[i]->Next = NULL;
}
for(i = 0; i < N; i++)
if(hashTable[i] >= 0 && hashTable[i] % N != i)
for(j = hashTable[i] % N; j != i; j = (j == N - 1 ? 0 : j + 1))
graph[j] = Insert(i, graph[j]);
return graph;
}

List Insert(int name, List L)
{
    int i;
    List p;
    p = (List)malloc(sizeof(struct list));
    p->Name = name;
    p->Next = NULL;
    if(L->Next == NULL)
        L->Next = p;
    else
    {
        p->Next = L->Next;
        L->Next = p;
    }
    return L;
}