When I needed to open bitmaps for a DOS game I was making, I couldn't find a way. I needed to open them because it was easier to create and modify them with the available graphics editors like MS Paint. So I fiddled around with the bitmap files until the header made sense to me. I ought to have documented the information properly, but I didn't so I am giving you the code below. I may elaborate on the format later on but until then you'll have to make sense out of the following function ;-).

The following code has been written for Turbo C++ 3.0. You'll have to #include <graphics.h> and call initgraph() before calling the function since the function in the current form uses functions present in the graphics.h library provided by Turbo C++. You can port the code easily by changing all the graphics output functions. Fseek(), fopen() etc are standard C/C++ functions of course. I thank Rajeev Sharma for pointing out the error in the originally posted code.

/* Function to open and display a 16-color bitmap file * Written by Vineeth Kaimal * For Turbo C++ 3.0 * http://writeka.com/emage/bmp16_format.html * Please retain these comments if you use the code. */ int loadbitmap(char *filename) { FILE *ptr=NULL; //file handle to open bitmap file int width,height; //width and height of the bitmap unsigned long temp=0,i=0,j=0; //some variables i need unsigned long ww; ptr=fopen(filename,"rb"); //open the bitmap file if(!ptr) return 0; //if its not there return width=0;height=0; //initialise wisth and height to zero fseek(ptr,18,SEEK_SET); //got to offset 18 in file for(i=0x1;i<=0x10000;i*=0x100) //read the width { temp=fgetc(ptr); width+=(temp*i); } fseek(ptr,22,SEEK_SET); //go to offset 22 in file for(i=0x1;i<=0x10000;i*=0x100) //read the height { temp=fgetc(ptr); height+=(temp*i); } ww=width; //ww is the number of reads to make for each horizontal line if(ww%2) //ww has to be half of width - since each pixel is only 4 bits of information ww++;ww/=2; //just getting the correct value if(ww%4) //now - ww is stored as sets of 4 pixels each - i think !?! :so this is the adjustment made ww=(ww/4)*4+4; //if width is less than ww*2 we ignore what we read fseek(ptr,119,SEEK_SET); //Ok! offset 119 - lets read the pixels - //remember the bitmap is stroed up - side - down int ch,ch1,ch2; for(i=0;i<height;i++) for(j=0;j<ww;j++) { ch=fgetc(ptr); //each character read is 2 pixels - yes 4 bits per pixel - so 16 colors ch1=ch;ch2=ch; //find those colors using bitwise ops ch1=ch1&(0xf0);ch1=ch1>>4; // ~~ ch2=ch2&(0x0f); // ~~ if(j*2<width) //ok so put the first pixel read on screen putpixel((j)*2,(height-1-i),getcol(ch1)); if(j*2+1<width) //put the second pixel read on screen putpixel((j)*2+1,(height-1-i),getcol(ch2)); } fclose(ptr); //close the file handle return 1; } int getcol(int col) { switch(col) { case 0: return 0; //BLACK; case 1: return 4; //RED; case 2: return 2; //GREEN case 3: return 6; //BROWN case 4: return 1; //BLUE; case 5: return 5; //MAGENTA; case 6: return 3; //CYAN; case 7: return 7; //LIGHTGRAY; case 8: return 8; //DARKGRAY; case 9: return 12; //LIGHTRED; case 10:return 10; //LIGHTGREEN case 11:return 14; //YELLOW; case 12:return 9; //LIGHTBLUE; case 13:return 13; //LIGHTMAGENTA case 14:return 11; //LIGHTCYAN; case 15:return 15; //WHITE; } return col; } You would have noticed the function getcol(int). This is because the numbers used to represent Turbo C++ colors differ from that of the bitmap format.

Its pretty easy to make sense of the headers if you spend some time on it. You may find the 256 color header a bit more difficult but RGB is pretty simple. I'll add those too at a later date.

Your feedback/questions/requests are welcome.