diff --git a/main.c b/main.c
index ca85578..08a1051 100644
--- a/main.c
+++ b/main.c
@@ -101,12 +101,13 @@ volatile uint16_t photoresistor_value = 0;
 /** photo-resistor voltage for the maximum brightness */
 #define PHOTORESISTOR_MAX 1.7
 /** factor to dim LED of the clock, depending on the ambient luminosity */
-float clock_brithtness = 0;
+float clock_brightness = 1;
 /** minimum LED brightness */
 #define BRIGHTNESS_MIN 0.2
 /** maximum LED brightness */
 #define BRIGHTNESS_MAX 1.0
-
+/** the factor to change the brightness */
+#define BRIGHTNESS_FACTOR 0.1
 
 int _write(int file, char *ptr, int len)
 {
@@ -236,11 +237,6 @@ static void clock_show_time(uint32_t time)
 	clock_leds[led_second*3+0] = 0xff-brightness_second;
 	//clock_leds[led_second*3+1] = 0; // clear other colors (minutes/hours indication)
 	//clock_leds[led_second*3+2] = 0; // clear other colors (minutes/hours indication)
-
-	// adjust brightness
-	for (uint16_t i=0; i<LENGTH(clock_leds); i++) {
-		clock_leds[i] *= clock_brithtness;
-	}
 }
 
 /** @brief set the LEDs
@@ -249,14 +245,8 @@ static void clock_show_time(uint32_t time)
  */
 static void clock_leds_set(void)
 {
-	static uint8_t clock_leds_old[WS2812B_LEDS*3] = {0}; // backup so to only set when value changed
 	for (uint16_t i=0; i<LENGTH(clock_leds)/3; i++) {
-		if (clock_leds[i*3+0]!=clock_leds_old[i*3+0] || clock_leds[i*3+1]!=clock_leds_old[i*3+1] || clock_leds[i*3+2]!=clock_leds_old[i*3+2]) { // only set when value changed (since this costs time)
-			clock_leds_old[i*3+0] = clock_leds[i*3+0]; // memorise change
-			clock_leds_old[i*3+1] = clock_leds[i*3+1]; // memorise change
-			clock_leds_old[i*3+2] = clock_leds[i*3+2]; // memorise change
-			ws2812b_set_rgb(i,gamma_correction_lut[clock_leds[i*3+0]],gamma_correction_lut[clock_leds[i*3+1]],gamma_correction_lut[clock_leds[i*3+2]]); // set new value (this costs time)
-		}
+		ws2812b_set_rgb(i,gamma_correction_lut[(uint8_t)(clock_leds[i*3+0]*clock_brightness)],gamma_correction_lut[(uint8_t)(clock_leds[i*3+1]*clock_brightness)],gamma_correction_lut[(uint8_t)(clock_leds[i*3+2]*clock_brightness)]); // set new value (this costs time)
 	}
 }
 
@@ -507,14 +497,16 @@ int main(void)
 			photoresistor_flag = false; // reset flag
 			action = true; // action has been performed
 			float photoresistor_voltage = photoresistor_value*1.2/ref_value; // calculate voltage from value
+			float new_clock_brightness = 0; // to calculate new brightness
 			if (photoresistor_voltage<PHOTORESISTOR_MAX) { // high ambient luminosity
-				clock_brithtness = BRIGHTNESS_MAX; // set highest brightness
+				new_clock_brightness = BRIGHTNESS_MAX; // set highest brightness
 			} else if (photoresistor_voltage>PHOTORESISTOR_MIN) { // low ambient luminosity
-				clock_brithtness = BRIGHTNESS_MIN; // set low brightness
+				new_clock_brightness = BRIGHTNESS_MIN; // set low brightness
 			} else { // intermediate ambient luminosity
-				clock_brithtness = BRIGHTNESS_MIN+(BRIGHTNESS_MAX-BRIGHTNESS_MIN)*(1-(photoresistor_voltage-PHOTORESISTOR_MAX)/(PHOTORESISTOR_MIN-PHOTORESISTOR_MAX)); // set variable brightness
+				new_clock_brightness = BRIGHTNESS_MIN+(BRIGHTNESS_MAX-BRIGHTNESS_MIN)*(1-(photoresistor_voltage-PHOTORESISTOR_MAX)/(PHOTORESISTOR_MIN-PHOTORESISTOR_MAX)); // set variable brightness
 			}
-			printf("%f, %f\n", photoresistor_voltage, clock_brithtness);
+			clock_brightness = clock_brightness*(1-BRIGHTNESS_FACTOR)+new_clock_brightness*BRIGHTNESS_FACTOR; // calculate new brightness based on factor
+			//printf("photo-resistor voltage: %f, clock brightness: %f\n", photoresistor_voltage, clock_brightness);
 		}
 		if (action) { // go to sleep if nothing had to be done, else recheck for activity
 			action = false;