conversion.c

#include <stdio.h>
#include <stdlib.h>
#include "header/function.h"

void convert_data(header *h, info_header *ih)
{
    unsigned int size = sizeof(header) + sizeof(info_header) + 256 * sizeof(color_table) + ih->width * ih->height * sizeof(greyscale);
    unsigned int data_offset = size - (ih->width * ih->height * sizeof(greyscale));
    h->file_size = size;          //changing file_size to contain the size of 8bit bmp file
    h->data_offset = data_offset; //new data_offset for 8bit bmp file
    ih->bpp = 8;
    ih->colors_used = 256;
}

unsigned char convert(rgb pic)
{
    return (pic.r * 0.299 + pic.g * 0.587 + pic.b * 0.114); //each component of the pixel is converted into a grayscale value
}

greyscale **RGBtoGrayscale(int height, int width, rgb **pic)
{
    greyscale **image = (greyscale **)malloc(height * sizeof(void *)); //image is a 2D array with its each element of type struct greyscale
    for (int i = 0; i < height; i++)
    {
        image[i] = (greyscale *)malloc(width * sizeof(greyscale)); //allocating memory for each row of 2D array image
    }
    for (int i = 0; i < height; i++)
        for (int j = 0; j < width; j++)
            image[i][j].value = convert(pic[i][j]); //calling convert function to change data of each pixel
    return image;
}

void get_ct(color_table ct[256]) //ct is a 1D array with its each element of the type struct color_table
{
    for (int i = 0; i < 256; i++)
    {
        ct[i].red = i;  //giving required values to red,green,blue of each struct
        ct[i].blue = i; //and reserved is set to zero for all elements of ct
        ct[i].green = i;
        ct[i].reserved = 0;
    }
}