adapted box color to gamma correction

generators/thimblerig.py

@@ -105,7 +105,7 @@ class Box():
                 for y in range(self.size):
                     if x == 0 or x == self.size - 1 \
                        or y == 0 or y == self.size -1:
-                        color = (0.2, 0.2, 0.2)
+                        color = (0.6, 0.6, 0.6)
                     else:
                         color = colorsys.hsv_to_rgb(self.hue, 1, 1)
                     try: