change black pixels to a random shade

src/screenmonitor.py

@@ -29,7 +29,8 @@ def capture_screenshot():
     for _ in range(black_pixels_count):
         x = random.randint(0, width - 1)
         y = random.randint(0, height - 1)
-        pixels[x, y] = (0, 0, 0)
+        shade = random.randint(0, 255)
+        pixels[x, y] = (shade, shade, shade)
 
     # Make 1% of the pixels copy themselves to their 8 neighbors
     for _ in range(neighbor_copy_pixels_count):