Question

I am opening a 3.5 MB file in C reading it into an unsigned char array Image data which I have initialized as follows:

unsigned char *** Imagedata;
Imagedata = new unsigned char**[1278];
for(int i=0; i<1278; i++){
    Imagedata[i]= new unsigned char*[968];
    for(int j=0; j<968; j++){
        Imagedata[i][j]= new unsigned char[3];
    }
}

Now i open the file and read it into the array as:

ifstream ifile;
ifile.open("abcde.raw", ios::in|ios::binary);
for(int i=0; i<1278; i++){
    for(int j=0; j<968; j++){
        for(int k=0; k<3; k++){
            ifile>>Imagedata[i][j][k];
        }
    }
}
ifile.close();

The next step is to just rewrite the bytes into a new file.. which i call rawfile.. I have tried to achieve it like this:

ofstream myfile;
myfile.open("rawfile.raw", ios::out|ios::binary);
for(int i=0; i<1278; i++){
    for(int j=0; j<968; j++){
        myfile.write((char *)Imagedata[i][j],3*sizeof(unsigned char));
    }
}
myfile.close();

It somehow doesn seem to work.. the image file that i get is garbage.. what could be the problem?

Answer 1

ifile>>Imagedata[i][j][k];

This is formatted input, it eats ‘whitespace’ characters even though you specified ios::binary. Use

Imagedata[i][j][k] = ifile.get();

Even better, allocate one big chunk of memory for the whole file and read it by one read call. What you do now is allocating a pointer for each pixel, which is very wasteful especially for 64-bit systems.