Thread: reading bitmap into array

I have a question regarding reading a bitmap image into an array. I understand that usually the first 54 bytes of the bitmap is for the header information, and basically I need to be able to read the whole image into the array, alter the non-header parts to encrypt the image and and write the array back out into a new bitmap image. I'm not sure how to extract the height and width information nor how the reading of the bytes to an array works.

For example, I have

Code:

typedef struct {
  char* data;
  char* header;
  int height;
  int width;
  int size;
} Bitmap;

and I want to be able to do this

Code:

/* The following function takes a file name and an address of
   a character array and read the file of characters into the
   array. Array and size are passed by their addresses
   Reads the BMP image from a file to an array
*/
void readImage(char* infile, Bitmap *bitmap){
  FILE * input = fopen(infile, "br");

}

Currently I'm a little clueless and have only gotten as far as opening the file in binary, can anyone give me a few hints as to how I go about this? Thanks a lot in advance.