в hex и обратно

#define FILENAME "D:\\test\\test.png"
#define OUT_HEX_FILE "D:\\test\\HEX.txt"
#define OUTFILENAME "D:\\test\\OUT.txt"
 
 
 
void ToHEX(const char * InFile, const char * OutFile)
{
    const size_t SIZE = 4096;
    char buf[SIZE];
    size_t red_bytes;
    ifstream in(InFile, ios::binary);
    if (!in)
    {
        cerr << InFile << " can't be oppened." << endl;
        exit(1);
    }
    ofstream out(OutFile);
    in.read(buf, sizeof(buf));
    while ((red_bytes = in.gcount()) > 0)
    {
        for (int i = 0; i < red_bytes; ++i)
        {
            //  cout << hex << static_cast<int>(buf[i]);
            //  out << hex << cal(buf[i]) * 16 + cal(buf[i]);       //static_cast<int>(buf[i]);
            out << hex << static_cast<int>(buf[i]);
        }
        in.read(buf, in.gcount());
    }
 
    out.close();
    in.close();
 
 
void ToFile(const char * InFile, const char * OutFile)
{
 
    ifstream file(InFile, ios::binary | ios::out);
    if (file.is_open())
    {
        const size_t SIZE = 4096;
        char c_hex[SIZE];
 
        file.read(c_hex, sizeof(c_hex));
    
 
        string hex(c_hex);
        basic_string<uint8_t> bytes;
 
        for (size_t i = 0; i < sizeof(c_hex); i += 2) {
            uint16_t byte;
            string nextbyte = hex.substr(i, 2);
            istringstream(nextbyte) >> std::hex >> byte;
            bytes.push_back(static_cast<uint8_t>(byte));
        }
    
        string result(begin(bytes), end(bytes));
 
        ofstream output_file(OutFile, ios::binary | ios::out);
        if (output_file.is_open()) {
            output_file << result;
            output_file.close();
        }
        else {
            cout << "Error could not create file." << endl;
        }
    }
}