diff --git a/src/test_png.c b/src/test_png.c
index a713fdf..5f4cc50 100644
--- a/src/test_png.c
+++ b/src/test_png.c
@@ -1,4 +1,3 @@
-#include <stdio.h>
 #include "render.h"
 #include "write_png.h"
 
@@ -9,15 +8,66 @@ int angle_to_pixel_white(double *angle, double *rgb) {
   return 0;
 }
 
-int main(){
-  int W = 9;
-  int H = 9;
-  double w = 1;
-  System system = {W, H, w, angle_to_pixel_white};
-
-  double buffer[W*H*3];
-
-  render(&system, buffer, 10000, 1.0/256, 1e-1);
-  write_png("test_white.png", buffer, W, H);
+int test(double *thetaphi, double *rgb){
+  int i = floor(8.0*thetaphi[0]/PI);
+  int j = floor(8.0*(thetaphi[1]+PI)/PI);
+  int k = (i+j)&1;
+  int l = floor(2*thetaphi[1]/PI);
+  rgb[0] = k;
+  rgb[1] = k;
+  rgb[2] = k;
+  switch (l%4) {
+    case 1:
+      rgb[1] = rgb[2] = 0;
+      break;
+    case 2:
+      rgb[0] = rgb[2] = 0;
+      break;
+    case 3:
+      rgb[0] = rgb[1] = 0;
+      break;
+    default:
+      break;
+  }
+  return 0;
+}
+
+int test2(double *thetaphi, double *rgb){
+  double tantheta = tan(PI-thetaphi[0]);
+  int i = (int)floor(4*tantheta*cos(thetaphi[1]));
+  int j = (int)floor(4*tantheta*sin(thetaphi[1]));
+  int k = (i+j)&1;
+  rgb[0] = 1-k;
+  rgb[1] = 1-k;
+  rgb[2] = 1-k;
+  return 0;
+}
+
+int test3(double *thetaphi, double *rgb){
+  double x = sin(thetaphi[0])*sin(thetaphi[1]);
+  double y = sin(thetaphi[0])*cos(thetaphi[1]);
+  double z = cos(thetaphi[0]);
+  double theta1 = atan2(hypot(z, x), y);
+  double phi1 = atan2(-z, x);
+  int i = (int)floor(16*theta1/PI);
+  int j = (int)floor(16*phi1/PI);
+  int k = (i+j)&1;
+  rgb[0] = 1-k;
+  rgb[1] = 1-k;
+  rgb[2] = 1-k;
+  return 0;
+}
+
+int main(){
+  int W = 1600;
+  int H = 900;
+  double w = 2;
+  System system = {W, H, w, test};
+
+  double *buffer = malloc(sizeof(double)*W*H*3);
+
+  render(&system, buffer, 10000, 1.0/256, 1e-1);
+  write_png("test_1.png", buffer, W, H);
+  free(buffer);
   return 0;
 }