Harvard CS50 filters

helpers.c

#include "helpers.h"
#include <stdio.h>
#include <math.h>

// Convert image to grayscale
void grayscale(int height, int width, RGBTRIPLE image[height][width])
{
    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            int avg = (image[i][j].rgbtRed + image[i][j].rgbtBlue + image[i][j].rgbtGreen) / 3;
            image[i][j].rgbtRed = avg;
            image[i][j].rgbtBlue = avg;
            image[i][j].rgbtGreen = avg;
        }
    }
    return;
}

// Convert image to sepia
void sepia(int height, int width, RGBTRIPLE image[height][width])
{
    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            float sepiaRed = .393 * image[i][j].rgbtRed + .769 * image[i][j].rgbtGreen + .189 * image[i][j].rgbtBlue;
            float sepiaGreen = .349 * image[i][j].rgbtRed + .686 * image[i][j].rgbtGreen + .168 * image[i][j].rgbtBlue;
            float sepiaBlue = .272 * image[i][j].rgbtRed + .534 * image[i][j].rgbtGreen + .131 * image[i][j].rgbtBlue;

            image[i][j].rgbtRed = (int) (sepiaRed <= 255) ? sepiaRed : 255;
            image[i][j].rgbtBlue = (int) (sepiaBlue <= 255) ? sepiaBlue : 255;
            image[i][j].rgbtGreen = (int) (sepiaGreen <= 255) ? sepiaGreen : 255;
        }
    }
    return;
}

// Reflect image horizontally
void reflect(int height, int width, RGBTRIPLE image[height][width])
{

    for (int i = 0; i < height; i++) {
        for (int j = 0; j < width / 2; j++) {
            int tempRed = image[i][j].rgbtRed;
            int tempBlue = image[i][j].rgbtBlue;
            int tempGreen = image[i][j].rgbtGreen;

            image[i][j].rgbtRed = image[i][width - 1 - j].rgbtRed;
            image[i][width - 1 - j].rgbtRed = tempRed;

            image[i][j].rgbtGreen = image[i][width - 1 - j].rgbtGreen;
            image[i][width - 1 - j].rgbtGreen = tempGreen;

            image[i][j].rgbtBlue = image[i][width - 1 - j].rgbtBlue;
            image[i][width - 1 - j].rgbtBlue = tempBlue;

        }
    }

    return;
}

// Blur image
void blur(int height, int width, RGBTRIPLE image[height][width])
{
    RGBTRIPLE ogImage[height][width];
    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            ogImage[i][j] = image[i][j];
        }
    }

    for (int i = 0, red, green, blue, counter; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            red = green = blue = counter = 0;

            if (i >= 0 && j >= 0)
            {
                red += ogImage[i][j].rgbtRed;
                green += ogImage[i][j].rgbtGreen;
                blue += ogImage[i][j].rgbtBlue;
                counter++;
            }
            if (i >= 0 && j - 1 >= 0)
            {
                red += ogImage[i][j-1].rgbtRed;
                green += ogImage[i][j-1].rgbtGreen;
                blue += ogImage[i][j-1].rgbtBlue;
                counter++;
            }
            if ((i >= 0 && j + 1 >= 0) && (i >= 0 && j + 1 < width))
            {
                red += ogImage[i][j+1].rgbtRed;
                green += ogImage[i][j+1].rgbtGreen;
                blue += ogImage[i][j+1].rgbtBlue;
                counter++;
            }
            if (i - 1 >= 0 && j >= 0)
            {
                red += ogImage[i-1][j].rgbtRed;
                green += ogImage[i-1][j].rgbtGreen;
                blue += ogImage[i-1][j].rgbtBlue;
                counter++;
            }
            if (i - 1 >= 0 && j - 1 >= 0)
            {
                red += ogImage[i-1][j-1].rgbtRed;
                green += ogImage[i-1][j-1].rgbtGreen;
                blue += ogImage[i-1][j-1].rgbtBlue;
                counter++;
            }
            if ((i - 1 >= 0 && j + 1 >= 0) && (i - 1 >= 0 && j + 1 < width))
            {
                red += ogImage[i-1][j+1].rgbtRed;
                green += ogImage[i-1][j+1].rgbtGreen;
                blue += ogImage[i-1][j+1].rgbtBlue;
                counter++;
            }
            if ((i + 1 >= 0 && j >= 0) && (i + 1 < height && j >= 0))
            {
                red += ogImage[i+1][j].rgbtRed;
                green += ogImage[i+1][j].rgbtGreen;
                blue += ogImage[i+1][j].rgbtBlue;
                counter++;
            }
            if ((i + 1 >= 0 && j - 1 >= 0) && (i + 1 < height && j - 1 >= 0))
            {
                red += ogImage[i+1][j-1].rgbtRed;
                green += ogImage[i+1][j-1].rgbtGreen;
                blue += ogImage[i+1][j-1].rgbtBlue;
                counter++;
            }
            if ((i + 1 >= 0 && j + 1 >= 0) && (i + 1 < height && j + 1 < width))
            {
                red += ogImage[i+1][j+1].rgbtRed;
                green += ogImage[i+1][j+1].rgbtGreen;
                blue += ogImage[i+1][j+1].rgbtBlue;
                counter++;
            }

            image[i][j].rgbtRed = round(red / (counter * 1.0));
            image[i][j].rgbtGreen = round(green / (counter * 1.0));
            image[i][j].rgbtBlue = round(blue / (counter * 1.0));
        }
    }

    return;
}

can u please tell me what is this this for filter less or more??