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我想能夠比較2個圖像（相同格式）並對這些圖像執行比特級比較。 1）爲標題創建結構.2）打開文件並從SOI標記的圖像數據偏移處開始讀取內容.3）將相應值存儲在3d數組或向量數組中.4）進行元素明智的比較，返回結果。我已經成功地使用fread（）爲bmp做了這個工作，並且使用了一個3d數組作爲容器，並使用可以分配和釋放內存的方法（但是bmp是未壓縮的圖像）。不知何故，這個過程對jpeg和tiff來說似乎要困難得多。即使理解了這兩種格式的標題格式，我的代碼卻說它不能讀取元素[45] [24]的顏色。我看過其他幾個選項，比如libjpeg和CImg，但我希望在跳入新圖書館之前獲得觀點。jpeg和tiff像素值提取
我對BMP代碼如下： ...喀嚓...
unsigned char*** create3dArray(FILE **fptr1,int height,int width,int depth)
{
unsigned char*** databuff = new unsigned char **[height];
// Allocate an array for each element of the first array
for(int x = 0; x < height; ++x)
{
databuff[x] = new unsigned char *[width];
// Allocate an array of integers for each element of this array
for(int y = 0; y < width; ++y)
{
databuff[x][y] = new unsigned char[depth];
// Specify an initial value (if desired)
for(int z = 0; z < depth; ++z)
{
databuff[x][y][z] = -1;
}
}
}
if ((sizeof(fheader) != 14) || (sizeof(iheader) != 40))
{
printf("Header structs are not properly packed\n");
return 0;
}
if (fread(&fheader, sizeof(fheader), 1, *fptr1) != 1)
{
printf("Couldn't read fheader.\n");
return 0;
}
if (fread(&iheader, sizeof(iheader), 1, *fptr1) != 1)
{
printf("Couldn't read iheader.\n");
return 0;
}
// uncomment to get an idea of what the headers look like.
if ((iheader.height != height) || (iheader.width != width) || (iheader.bits != 24))
{
printf("This only works for 512x512 24-color bitmaps\n");
return 0;
}
if (fheader.offset != 54) {
printf("This only works if the offset is equal to 54\n");
return 0;
}
for (int i = 0; i < iheader.height; i++) {
for (int j = 0; j < iheader.width; j++) {
if (fread(&databuff[i][j][0], 3, 1, *fptr1) != 1){
printf("Couldn't read colors for element [%d][%d]\n", i, j);
return 0;
}
}
}
return databuff;
}
template <typename Tx>
void destroy3dArray(Tx*** myArray)
{
delete[] **myArray;
delete[] *myArray;
delete[] myArray;
}
int main()
{
FILE *fptr1,*fptr2; // two file pointers one for each file.
int count=0;
float total_bits=0;
float ber=0; //variable for bit error rate
int width,height,depth;
cout<<"Please enter height of the image "<<endl;
cin>>height;
cout<<"Please enter width of the image "<<endl;
cin>>width;
cout<<"Please enter depth of the image. The max depth can be 3 for RGB values"<<endl;
cin>>depth;
char *filename = "lena512.bmp";
char *filename2 = "lena512_2.bmp";
//std::string trueBinaryDataInString[512][512][3];
if ((fptr1 = fopen(filename, "r")) == NULL) {
printf("Coulsn't open file %s for reading.\n", filename);
return 1;
}
unsigned char*** trueArray = create3dArray(&fptr1,height,width,depth);
for(int i=0;i<height;i++)
{
//std::cout << "Row " << i << std::endl;
for(int j=0;j<width;j++)
{
for(int k=0;k<depth;k++)
{
total_bits += ToBinary(trueArray[i][j][k]).length();
}
//std::cout<<endl;
}
//std::cout<<endl;
}
std::cout << total_bits<<endl;
//createAnddestroy3dArray<unsigned char> MyArray;
if ((fptr2 = fopen(filename2, "r")) == NULL) {
printf("Coulsn't open file %s for reading.\n", filename2);
return 1;
}
unsigned char*** trueArray2 = create3dArray(&fptr2,height,width,depth);
/*for(int i=0;i<512;i++)
{
std::cout << "Row " << i << std::endl;
for(int j=0;j<512;j++)
{
for(int k=0;k<3;k++)
{
std::cout<<" "<<ToBinary(trueArray2[i][j][k]);
}
std::cout<<endl;
}
std::cout<<endl;
}
*/
/******** BIT Error Rate Calculation ******/
for(int i=0;i<height;i++)
{
for(int j=0;j<width;j++)
{
for(int k=0;k<depth;k++)
{
if(ToBinary(trueArray[i][j][k])!= ToBinary(trueArray2[i][j][k]))
{
std::cout<<ToBinary(trueArray[i][j][k])<< " " <<ToBinary(trueArray2[i] [j][k])<<endl;
count++;
}
else
continue;
}
}
}
ber = (count/total_bits)*100;
std::cout<<"Bit Error Rate (BER) = "<<ber<<endl;
destroy3dArray<unsigned char>(trueArray); //Deallocating memory for array 1
destroy3dArray<unsigned char>(trueArray2); //Deallocating memory for array 2
return 0;
}
所以我必須首先將這些文件格式轉換成bmp的。如先載入jpg，然後將其保存爲bmp，然後使用這些文件。如果是，那麼狀態的改變是否會影響任何標題信息？ – user1227372 2012-07-12 21:23:27
不一定要重新保存到.BMP中，這也是可能的。答案中提到的庫允許您在內存中加載和解壓縮，而不保存到中間文件中。這些庫還允許您訪問原始文件的元數據，以備需要時使用。 – 2012-07-12 22:21:34