 
    int ledBrightness[GRID_SIZE_X]; // RGB intensity
    float dLedBrightness = 1.0 / (GRID_SIZE_X - 1);
+   float dLightness = 1.0 / (GRID_SIZE_X + 1); // Will drop lightness = 0 (black) and 1 (white), since that results in
+                                               // an entire row/column being all the same (fully off or fully on).
    float lightness[GRID_SIZE_X]; // HSL
    float saturation[GRID_SIZE_X]; // HSL
    
-   ledBrightness[0] = 0;
+   ledBrightness[0]               = 0;
    ledBrightness[GRID_SIZE_X - 1] = 255;
 
-   saturation[0] = lightness[0] = 0;
-   saturation[GRID_SIZE_X - 1] = lightness[GRID_SIZE_X - 1] = 1;
+   saturation[0]                  = 0;
+   saturation[GRID_SIZE_X - 1]    = 1;
 
    float v;
 

      v = i * dLedBrightness;   // Linear
      saturation[i] = v;
      v = pow( v, exponent);    // Non-linear
      lightness[i] = v;
      ledBrightness[i] = v * 256; // Don't need to constrain; won't get close to 255.
   }

   // // Debug:
   // for (i = 0; i < GRID_SIZE_X; i++)

      strip.show();
      delay( run < 3 ? 5000 : 20000); // Delay longer for HSL part of run
   }

   // Since we skipped "black" and "white", show a checkerboard of those.

   clearStrip();
   c = Color( 255, 255, 255);
   for (i = 0; i < 25; i += 2)
      strip.setPixelColor( i, c);
   strip.show();
   delay( 5000);

   // for (run = 0; run < 3; run++)
   // {
   //    for (y = 0; y < 5; y++)
