use 256 shades of grey

mandelbrot.c

@@ -2,12 +2,15 @@
 #include <complex.h>
 #include <stdbool.h>
 
+/* The maximum iteration count. */
+const int max_it = 170;
+
 /* Compute the out-coloring based on the iteration counter. */
 Uint32 outcolor(int it) {
-  return 0x00010001 * it;
+  return 0x00010001 * ((it * 0xff) / max_it);
 }
 
-/* Compute the in-coloring. */
+/* "Compute" the in-coloring. */
 Uint32 incolor() {
   return 0x00000000; /* black */
 }
@@ -28,7 +31,6 @@ void drawmandelbrot(SDL_Surface *surface) {
     bool diverges = false;
     float complex z = 0;
     int it;
-    const int max_it = 170;
     for (it = 1; it <= max_it; it++) {
       /* z = z² + c */
       z = cpowf(z, 2) + c;