Write small bmp on console via C++ - c++

Question

I'm trying to read painted 16x16 bmp, but there is no 1 pixel = 3 bits (RGB). Even if first 4-5 lines is white and the rest is black the document is still full of 255 255 255 for each pixel.
In my case I need to show this image in console by analyzing RGB layers of each pixel but have a lot of trouble with it.
int main()
{
FILE* f = fopen("image.bmp", "rb");
unsigned char info[54];
fread(info, sizeof(unsigned char), 54, f); // read the 54-byte header
// extract image height and width from header
int width = *(int*)&info[18];
int height = *(int*)&info[22];
int size = 3 * width * height;
unsigned char * data = new unsigned char[size]; // allocate 3 bytes per pixel
fread(data, sizeof(unsigned char), size, f); // read the rest of the data at once
fclose(f);
for (int i = 0; i < size; i += 3)
{
unsigned char tmp = data[i];
data[i] = data[i + 2];
data[i + 2] = tmp;
}
unsigned int * byteData = new unsigned int[size];
for (int i = 0; i <= size; i++)
{
byteData[i] = (int) data[i];
}
for (int i = 0; i <= size / 3; i++)
{
cout << i << ".\t" << byteData[i] << "\t" << byteData[i + 1] << "\t" << byteData[i + 2] << endl;
}
cout << endl;
cout << "=======================" << endl;
for (int j = 0; j < width; j++)
{
cout << j + 1 << ".\t";
for (int i = 0; i < height; i++)
{
//if ((int)data[j * width + i] >= 100 && (int)data[j * width + i + 1] >= 100 && (int)data[j * width + i + 2] >= 100)
if (((int) data[j * width + i] + (int) data[j * width + i + 1] + (int) data[j * width + i + 2]) / 3 <= 170)
cout << " ";
else cout << "*";
}
cout << endl;
}
getchar();
return 0;
}
As I think problem with byte sequenses and reading memory frome garbage, but if you could explain where is leak?

Answer 1

The solution is next: bmp should be created with 24 bpp and top-down row order.
Correct code is for 16x16 bitmap:
#include <iostream>
using namespace std;
unsigned char* readBMP(char* filename);
int main()
{
unsigned char * data = readBMP("winLogo.bmp");
int size = 16*16*3;
unsigned int * byteData = new unsigned int[size];
for (int i = 0; i <= size; i++)
{
byteData[i] = (int)data[i];
}
int k = 0;
//uncomment to write a line of RGB values
//for (int i = 0; i < size; i += 3)
//{
// cout << k+1 << ".\t" << byteData[i] << "\t" << byteData[i + 1] << "\t" << byteData[i + 2] << endl;
// k++;
//}
for (int i = 0; i < size; i+= 3)
{
if (i % 16*3 == 0)
{
cout << endl << (i/(16*3))+1 << ".\t";
}
else {};
if (byteData[i] >= 200 && byteData[i + 1] >= 200 && byteData[i + 2] >= 200)
cout << " ";
else
cout << "#";
}
getchar();
return 0;
}
unsigned char* readBMP(char* filename)
{
int i;
FILE* f = fopen(filename, "rb");
unsigned char info[54];
fread(info, sizeof(unsigned char), 54, f); // read the 54-byte header
// extract image height and width from header
int width = *(int*)&info[18];
int height = *(int*)&info[22];
int size = -3 * width * height;
unsigned char* data = new unsigned char[size]; // allocate 3 bytes per pixel
fread(data, sizeof(unsigned char), size, f); // read the rest of the data at once
fclose(f);
//BGR -> RGB
for (i = 0; i < size; i += 3)
{
unsigned char tmp = data[i];
data[i] = data[i + 2];
data[i + 2] = tmp;
}
return data;
}