arduino fritzing led matrix shades of gray

gray.ino

int rowPins[8] = {
  9,22,18,12,15,11,7,8};         // matrix rows connected to the Arduino
int colPins[8] = {
  13,8,17,10,5,16,19,14};       // matrix columns connected to the Arduino

int image[8][8]={                              // the image displayed on the matrix : 1 = LED on, 0 = LED off
  
{1  , 1 , 1  , 1  , 1  , 1  , 1  , 1 },
{2  , 2 , 2  , 2  , 2  , 2  , 2  , 2 },
{3  , 3 , 3  , 3  , 3  , 3  , 3  , 3 },
{4  , 4 , 4  , 4  , 4  , 4  , 4  , 4 },
{6  , 6 , 6  , 6  , 6  , 6  , 6  , 6 },
{8  , 8 , 8  , 8  , 8  , 8  , 8  , 8 },
{10  , 10 , 10  , 10  , 10  , 10  , 10  , 10 },
{12  , 12 , 12  , 12  , 12  , 12  , 12  , 12 },

};                                         

void setup(){
  for (int i=0; i<8; i++){                       // all pins are declared as outputs 
    pinMode(rowPins[i],OUTPUT);
    pinMode(colPins[i],OUTPUT);
  }
}

unsigned int counter;
unsigned int ticker;

int mode = 0;

void loop(){
loop:
  counter++;

    if (counter % 100 == 0) {
     tick();
    }

  for (int y=0; y<8; y++){                       // rowwise 
    for (int x=0; x<8; x++){                     // check all entries of the array from left to right 
      digitalWrite(colPins[x], (counter % image[x][y] == 0) ? HIGH : LOW);           // switch on column pin
    }
    int pin = rowPins[y];
    digitalWrite(pin,LOW);                // switch the row pin to LOW (because it is the cathode of the LED; LOW means ON)
      delayMicroseconds(60);                      // stop the program for 100 milliseconds
    digitalWrite(pin,HIGH);               // switch the row pin to HIGH (this means OFF)
  }
  goto loop;

}

void tick() {
      for (int y=0; y<8; y++){                       // rowwise 
      for (int x=0; x<8; x++){                     // check all entries of the array from left to right 
        switch (mode) {
          case 0: image[x][y] = int((sin(x+y+counter)+1)*3)+1; break;
          case 1: image[x][y] = int((tan(y-x+counter)+1)*3)+1; break;
          case 2: image[x][y] = int((cos(y+counter)+1)*3)+1; break;
          case 3: image[x][y] = int((sin(x-y+counter)+1)*3)+1; break;
          case 4: image[x][y] = int((tan(x+counter)+1)*3)+1; break;
        }
      }
    }

    if (++ticker % 15 == 0 && ++mode > 4) {
      mode = 0;
    }

}