fix: add vignette and other filter logic to helpers.c

Author: saumya1317

helpers.c

@@ -9,12 +9,21 @@ int max(int a,int b){
     return b;
 }
 void grayscale(int height, int width, RGBTRIPLE image[height][width]){
-    return;
-    
-// Convert image to grayscale
-
+   
+    for(int i = 0; i < height; i++){
+        for(int j = 0; j < width; j++){
+            int red = image[i][j].rgbtRed;
+            int green = image[i][j].rgbtGreen;
+            int blue = image[i][j].rgbtBlue;
+            int avg = (red + green + blue) / 3;
+            image[i][j].rgbtRed = avg;
+            image[i][j].rgbtGreen = avg;
+            image[i][j].rgbtBlue = avg;
+        }
+    }
 }
 
+
 void invert(int height, int width, RGBTRIPLE image[height][width]){
     for(int i = 0; i<height; i++){
         for(int j = 0; j<width; j++){
@@ -66,4 +75,23 @@ void blur(int height, int width, RGBTRIPLE image[height][width]){
 
 // Blur image
 
+}
+void vignette(int height, int width, RGBTRIPLE image[height][width]){
+    float cx = width / 2.0; //  center of the image
+    float cy= height / 2.0;
+    float max_dis= sqrt(cx * cx + cy * cy);
+    for(int i = 0; i < height; i++){
+    for(int j = 0; j < width; j++){
+            float disx = j - cx;
+            float disy = i - cy;
+            float dist= sqrt(disx * disx + disy * disy);
+            //  (0.0 = dark, 1.0 = og)
+            float vig = 1.0 - (dist/ max_dis);
+            if(vig< 0.0) vig = 0.0;
+            if(vig > 1.0) vig = 1.0;
+            image[i][j].rgbtRed = (int)(image[i][j].rgbtRed * vig);
+            image[i][j].rgbtGreen = (int)(image[i][j].rgbtGreen * vig);
+            image[i][j].rgbtBlue = (int)(image[i][j].rgbtBlue * vig);
+        }
+    }
 }