Save a 24 bit bitmap's pixel data to File in BMP format

Introduction

This tip is about saving a 24 bit bmp image to a file given the raw bitmap bits containing drawing data in pixels and the width and height of the image.

The code

// szPathName : Specifies the pathname
// lpBits	 : Specifies the bitmap bits
// w	: Specifies the image width
// h	: Specifies the image height

bool SaveImage(char* szPathName, void* lpBits, int w, int h)

{ 

//Create a new file for writing

FILE *pFile = fopen(szPathName, "wb");

if(pFile == NULL)

{ 

return false;

}

BITMAPINFOHEADER BMIH;

BMIH.biSize = sizeof(BITMAPINFOHEADER);

BMIH.biSizeImage = w * h * 3;

// Create the bitmap for this OpenGL context

BMIH.biSize = sizeof(BITMAPINFOHEADER);

BMIH.biWidth = w;

BMIH.biHeight = h;

BMIH.biPlanes = 1;

BMIH.biBitCount = 24;

BMIH.biCompression = BI_RGB;

BMIH.biSizeImage = w * h* 3; 

BITMAPFILEHEADER bmfh;

int nBitsOffset = sizeof(BITMAPFILEHEADER) + BMIH.biSize; 

LONG lImageSize = BMIH.biSizeImage;

LONG lFileSize = nBitsOffset + lImageSize;

bmfh.bfType = 'B'+('M'<<8);

bmfh.bfOffBits = nBitsOffset;

bmfh.bfSize = lFileSize;

bmfh.bfReserved1 = bmfh.bfReserved2 = 0;

//Write the bitmap file header

UINT nWrittenFileHeaderSize = fwrite(&bmfh, 1, 

sizeof(BITMAPFILEHEADER), pFile);

//And then the bitmap info header

UINT nWrittenInfoHeaderSize = fwrite(&BMIH, 

1, sizeof(BITMAPINFOHEADER), pFile);

//Finally, write the image data itself 

//-- the data represents our drawing

UINT nWrittenDIBDataSize = 

fwrite(lpBits, 1, lImageSize, pFile);

fclose(pFile);

 

return true;



}

History

Tip uploaded : 16th March, 2012