pertbanking/Bitmap

C++ header file for representing bitmap images as a matrix of RGB pixels

C++ Bitmap header files

Getting Started

1. Clone this repository onto your development environment
2. Copy bitmap.h and bitmap.cpp to your project directory
3. In your C++ program file, include the header file with #include "bitmap.h"
4. Declare your variables of type Bitmap or Pixel.

See the guides for the Bitmap and Pixel data types below.

Pixel

Represents a single Pixel in the image. A Pixel has red, green, and blue components that are mixed to form a color. Each of these values can range from 0 to 255.

By default, a pixel is black with 0 red, 0 green, and 0 blue. There is an overloaded constructor that takes three integer arguments for the red, green, and blue components.

Each component is mutable using the member variables red green and blue. They should have values between 0 and 255 but this class does not validate the component values as long as they are assigned integers.

Example of use

Pixel purpleDot;

purpleDot.red = 255;
purpleDot.green = 0;
purpleDot.blue = 255;

Bitmap

Represents a bitmap where a grid of pixels (in row-major order) describes the color of each pixel within the image. Limited to Windows BMP formatted images with no compression and 24 bit color depth.

Functions

open

void open(std::string)

Opens a file as its name is provided and reads pixel-by-pixel the colors into a matrix of RGB pixels. Any errors will cout but will result in an empty matrix (with no rows and no columns).

parameter: name of the filename to be opened and read as a matrix of pixels

save

void save(std::string)

Saves the current image, represented by the matrix of pixels, as a Windows BMP file with the name provided by the parameter. File extension is not forced but should be .bmp. Any errors will cout and will NOT attempt to save the file.

isImage

bool isImage()

Validates whether or not the current matrix of pixels represents a proper image with non-zero-size rows and consistent non-zero-size columns for each row. In addition, each pixel in the matrix is validated to have red, green, and blue components with values between 0 and 255

return: boolean value of whether or not the matrix is a valid image

toPixelMatrix

std::vector <std::vector <Pixel> > toPixelMatrix()

Provides a vector of vector of pixels representing the bitmap

return: the bitmap image, represented by a matrix of RGB pixels

fromPixelMatrix

void fromPixelMatrix(const std::vector <std::vector <Pixel> > &)

Overwrites the current bitmap with that represented by a matrix of pixels. Does not validate that the new matrix of pixels is a proper image.

parameter: a matrix of pixels to represent a bitmap

Example of use

#include <vector>
#include "bitmap.h"

using namespace std;

int main()
{
  Bitmap image;
  vector <vector <Pixel> > bmp;
  Pixel rgb;

  //read a file example.bmp and convert it to a pixel matrix
  image.open("example.bmp");

  //verify that the file opened was a valid image
  bool validBmp = image.isImage();

  if( validBmp == true )
  {
    bmp = image.toPixelMatrix();
  

    //take all the redness out of the top-left pixel
    rgb = bmp[0][0];
    rgb.red = 0; 

    //put changed image back into matrix, update the bitmap and save it
    bmp[0][0] = rgb;
    image.fromPixelMatrix(bmp);
    image.save("example.bmp");
  }
  return 0;
}