read image in 2d array C++ and save it - c++

Question

#include <iostream>
#include <fstream> // for file I/O
#define WIDTH 128
#define HEIGHT 128
#include <cmath>
using namespace std;
typedef unsigned char unchar;
class MImage
{
///////////////////////////////////////////////////////////////////////////////////////read
public:
void readimage()
{
imageData = new unchar*[HEIGHT]; // create new array size: height of image.
for (int i = 0; i < HEIGHT; i++)
{
imageData[i] = new unchar[WIDTH]; //create matrix.
}
//image I/O
pInFile = new ifstream;
pInFile->open("L.bmp", ios::in | ios::binary); // open fileName and read as binary.
pInFile->read(reinterpret_cast<char*>(imageHeaderData), 1078); //read bmp header data into array.
for (int i = 0; i < HEIGHT; i++)
{
pInFile->read(reinterpret_cast<char*>(imageData[i]), WIDTH); //read row into each array entry.
}
pInFile->close(); //close stream.
}
public:
void write()
{
//smoothFilter();
pOutFile = new ofstream;
pOutFile->open("output.bmp", ios::out | ios::binary);
pOutFile->write(reinterpret_cast<char*>(imageHeaderData), 1078); //write header data onto output
for (int i = 0; i < HEIGHT; i++)
{
pOutFile->write(reinterpret_cast<char*>(imageData[i]), WIDTH); // write new image data.
}
pOutFile->close(); //close stream
}
public:
ifstream* pInFile;
ofstream* pOutFile;
unchar imageHeaderData[1078]; //.bmp header data with offset 1078. unchar** imageData;
};
int main()
{
MImage abc;
abc.readimage();
abc.write();
return 0;
}
I am unable to read image in a 2d array so that i could do some processing on it. i have used the code above but saved file is giving error.
what i am doing is first reading a .bmp file 128x128 then saving it in an other .bmp file. but when i try to open output file it gives error "file is corrupted or large in size"

Answer 1

Hope it helps ;)
I skipped error checking but you should add it to the final code. For writing a .bmp image, wirte BITMAPFILEHEADER first, then BITMAPINFOHEADER and at the end the actual raw data
FILE* filePtr;
int error;
unsigned int count;
BITMAPFILEHEADER bitmapFileHeader;
BITMAPINFOHEADER bitmapInfoHeader;
int imageSize;
unsigned char* bitmapImage;
// Open the height map file in binary.
error = fopen_s(&filePtr, filename, "rb");
// Read in the file header.
count = fread(&bitmapFileHeader, sizeof(BITMAPFILEHEADER), 1, filePtr);
// Read in the bitmap info header.
count = fread(&bitmapInfoHeader, sizeof(BITMAPINFOHEADER), 1, filePtr);
// Save the dimensions of the terrain.
Width= bitmapInfoHeader.biWidth;
Height= bitmapInfoHeader.biHeight;
// Calculate the size of the bitmap image data.
imageSize = Width* Height* 3;
// Allocate memory for the bitmap image data.
bitmapImage = new unsigned char[imageSize];
// Move to the beginning of the bitmap data.
fseek(filePtr, bitmapFileHeader.bfOffBits, SEEK_SET);
// Read in the bitmap image data.
count = fread(bitmapImage, 1, imageSize, filePtr);
// Close the file.
error = fclose(filePtr);
Don't forget to delete bitmapImage or use std::vector instead