【OpenCV学习】图像装载函数的模拟加载24BPP的BMP文件

作者：gnuhpc
出处：http://www.cnblogs.com/gnuhpc/

/*
文中出现的注释若为三项注释，则依次为：
Offset      Size     Purpose 
*/
#include <iostream>
#include <cstdio>
#include <cstdlib>

#include <cv.h>
#include <highgui.h>

using namespace std;

/*****[自己画图用的构造体]*****/
struct Image {
    unsigned long sizeX;
    unsigned long sizeY;
    char *data;
};
typedef struct Image Image;


/****[BMP图像导入]**************/
int ImageLoad(char *filename, Image *image)
{
    FILE *file;
    unsigned long size;
    unsigned long i;
    unsigned short int planes;
    unsigned short int bpp;
    
    char temp;
    
    
    if ((file = fopen(filename, "rb"))==NULL)//读入文件
    {
        printf("File Not Found : %s/n",filename);
        return 0;
    }
    
    fseek(file, 18, SEEK_CUR);//直接跳到宽度信息读取部分
    
    /*读取宽度信息：18     4     the bitmap width in pixels (signed integer).*/
    if ((i = (unsigned long)fread(&image->sizeX, 4, 1, file)) != 1) {
        printf("Error reading width from %s./n", filename);
        return 0;
    }
    
    /*读取高度信息:22     4     the bitmap height in pixels (signed integer).*/
    if ((i = (unsigned long)fread(&image->sizeY, 4, 1, file)) != 1) {
        printf("Error reading height from %s./n", filename);
        return 0;
    }
    
    size = image->sizeX * image->sizeY * 3;//三通道
    /*读取色彩平面个数（必须为1）
    26     2     the number of color planes being used. Must be set to 1.*/
    if ((fread(&planes, 2, 1, file)) != 1) {
        printf("Error reading planes from %s./n", filename);
        return 0;
    }
    if (planes != 1) {
        printf("Planes from %s is not 1: %u/n", filename, planes);
        return 0;
    }
    
    /*读取像素深度
    28     2     the number of bits per pixel, which is the color depth of the image. 
    Typical values are 1, 4, 8, 16, 24 and 32.*/
    if ((i = (unsigned long)fread(&bpp, 2, 1, file)) != 1) {
        printf("Error reading bpp from %s./n", filename);
        return 0;
    }
    if (bpp != 24) {
        printf("Bpp from %s is not 24: %u/n", filename, bpp);
        return 0;
    }
    
    fseek(file, 24, SEEK_CUR);
    
    image->data = (char *) malloc(size);
    if (image->data == NULL) {
        printf("Error allocating memory for color-corrected image data");
        return 0;
    }
    
    if ((i = (unsigned long)fread(image->data, size, 1, file)) != 1) {
        printf("Error reading image data from %s./n", filename);
        return 0;
    }
    
    for (i=0;i<size;i+=3) {
        temp = image->data[i];
        image->data[i] = image->data[i+2];
        image->data[i+2] = temp;
    }//RGB<->BGR
    
    return 1;
}


/*****[准备装载图像]******************/
IplImage *imgA;
CvSize window_size;

void LoadImage()
{
    
    Image *image1;
    
    image1 = (Image *) malloc(sizeof(Image));
    if (image1 == NULL) {
        printf("Error allocating space for image");
        return ;
    }
    
    if (!ImageLoad("test2.bmp", image1)) 
    { 
        return ;
    }
    
    window_size.width = image1->sizeX;
    window_size.height= image1->sizeY;
    imgA = cvCreateImage(window_size,IPL_DEPTH_8U,3);
    imgA->imageData = image1->data;
    
    free(image1);
    
    cvCvtColor(imgA, imgA, CV_RGB2BGR);
    cvFlip(imgA,NULL,0);
    
}




int main( int argc, char **argv)
{
    
    LoadImage();
    cvNamedWindow("MY FUNCTION",CV_WINDOW_AUTOSIZE);
    cvShowImage("MY FUNCTION",imgA);
    
    
    /*OpenCV*/
    IplImage *imgB = cvLoadImage( "test2.bmp", CV_LOAD_IMAGE_ANYDEPTH | CV_LOAD_IMAGE_ANYCOLOR);
    if(imgB ==NULL)
    {
        cout<<"Can't Load Image ." << endl;
        exit(0);
    }
    cvNamedWindow("OpenCV FUNC",CV_WINDOW_AUTOSIZE);
    cvShowImage("OpenCV FUNC",imgB);

    
    cvWaitKey(0);
    
    free(imgA->imageData);
    cvReleaseImage( & imgA);
    cvReleaseImage( & imgB);
    cvDestroyAllWindows();
    
    return 0;
}

作者：gnuhpc
出处：http://www.cnblogs.com/gnuhpc/