Merge pull request #27 from Satvik-Singh192/threshold-filter

feat: add threshold (black & white) filter with -t flag

Author: harshsankhla18

README.md

@@ -128,6 +128,22 @@ The vignette filter gives an image a cinematic look by gradually darkening its c
 
 If you apply this algorithm, your resulting image will have gently darkened corners and an undisturbed/sunnier center.
 
+### 6.) The Threshold Algorithm
+
+The “threshold” filter converts a colorful image into a pure black-and-white one based on pixel intensity.
+
+For each pixel, the intensity is calculated as the average of its red, green, and blue values:
+
+\[
+\text{intensity} = \frac{(R + G + B)}{3}
+\]
+
+If the intensity is **greater than or equal to 128**, the pixel is set to **white** (`R = G = B = 255`).
+Otherwise, it is set to **black** (`R = G = B = 0`).
+
+This results in a high-contrast, two-tone image where all intermediate shades are eliminated — essentially a hard binary “black-and-white” conversion.
+
+
 ---
 
 ### Usage

filter.c

@@ -7,7 +7,7 @@
 int main(int argc, char *argv[])
 {
     // Define allowable filters
-    char *filters = "bgrsiv";
+    char *filters = "bgrsivt";
 
 
     char filterArr[argc-3];
@@ -128,6 +128,9 @@ int main(int argc, char *argv[])
         case 'v':
             vignette(height, width, image);
             break;
+        case 't':
+            threshold(height, width, image);
+            break;
         default:
             printf("%c", &filterArr[i]);
             break;

helpers.c

@@ -171,3 +171,30 @@ void vignette(int height, int width, RGBTRIPLE image[height][width]){
         }
     }
 }
+
+//Threshold Filter(Black & White)
+void threshold(int height, int width, RGBTRIPLE image[height][width])
+{
+    for (int i = 0; i < height; i++)
+    {
+        for (int j = 0; j < width; j++)
+        {
+            int avg = round((image[i][j].rgbtRed +
+                             image[i][j].rgbtGreen +
+                             image[i][j].rgbtBlue) / 3.0);
+
+            if (avg >= 128)
+            {
+                image[i][j].rgbtRed = 255;
+                image[i][j].rgbtGreen = 255;
+                image[i][j].rgbtBlue = 255;
+            }
+            else
+            {
+                image[i][j].rgbtRed = 0;
+                image[i][j].rgbtGreen = 0;
+                image[i][j].rgbtBlue = 0;
+            }
+        }
+    }
+}

helpers.h

@@ -15,4 +15,7 @@ void reflect(int height, int width, RGBTRIPLE image[height][width]);
 // Blur image
 void blur(int height, int width, RGBTRIPLE image[height][width]);
 // Vignette image
-void vignette(int height, int width, RGBTRIPLE image[height][width]);
+void vignette(int height, int width, RGBTRIPLE image[height][width]);
+
+//Threshold Filter(Black & White)
+void threshold(int height, int width, RGBTRIPLE image[height][width]);