jindingwang / cbmp

C library for reading, manipulating, and saving BMP images.

C BMP

C Library to read, manipulate, and save BMP images.

Image must be a valid BMP format with 24 or 32 bit pixel data.

Usage

In order to use the library, move cbmp.c and cbmp.h into your project. Link the cbmp.c file when compiling and include the cbmp.h file at the top of the file you are using it in.

Example

This example reads a BMP image and applies an invert to the pixels. It then saves the inverted image to a new file.

#include <stdlib.h>
#include <stdio.h>
#include "cbmp.h"

int main(int argc, char** argv)
{

    if (argc != 3)
    {
        fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
        exit(1);
    }

    // Read image into BMP struct
    BMP* bmp = bopen(argv[1]);

    unsigned int x, y, width, height;
    unsigned char r, g, b;

    // Gets image width in pixels
    width = get_width(bmp);

    // Gets image height in pixels
    height = get_height(bmp);

    for (x = 0; x < width; x++)
    {
        for (y = 0; y < height; y++)
        {
            // Gets pixel rgb values at point (x, y)
            get_pixel_rgb(bmp, x, y, &r, &g, &b);

            // Sets pixel rgb values at point (x, y)
            set_pixel_rgb(bmp, x, y, 255 - r, 255 - g, 255 - b);
        }
    }

    // Write bmp contents to file
    bwrite(bmp, argv[2]);

    // Free memory
    bclose(bmp);

    return 0;
}

Full API

// Reads a BMP image and returns a poiner to a BMP struct
BMP* bopen(char* file_path);

// Returns a deep copy of the BMP passed
BMP* b_deep_copy(BMP* to_copy);

// Takes a BMP pointer and returns the image width in pixels
int get_width(BMP* bmp);

// Takes a BMP pointer and returns the image height in pixels
int get_height(BMP* bmp);

// Takes a BMP pointer and returns the image depth in bytes
unsigned int get_depth(BMP* bmp);

// Takes a BMP pointer, (x, y), and sets the values of rgb pointers
void get_pixel_rgb(BMP* bmp, int x, int y, unsigned char* r, unsigned char* g, unsigned char* b);

// Takes a BMP pointer, (x, y), and rgb values and updates the pixel color
void set_pixel_rgb(BMP* bmp, int x, int y, unsigned char r, unsigned char g, unsigned char b);

// Writes the contents of the BMP pointer to the given file path
void bwrite(BMP* bmp, char* file_name);

// Frees all memory allocated for the BMP pointer
void bclose(BMP* bmp);

Testing

In order to run tests, create a build directory and enter it:

mkdir build
cd build

Generate Makefiles with cmake:

cmake ..

Build executable:

make

Run the tests executable:

./tests