chore: improve colour smoothing

src/mandelbrot.rs

@@ -126,7 +126,7 @@ impl Mandelbrot {
         }
 
         if num_iters < max_iterations {
-            (num_iters as f64) - z.norm() / 2f64.ln()
+            (num_iters as f64 + 1.0) - z.norm().ln().ln() / 2f64.ln()
         } else {
             num_iters as f64
         }