Update index.js

index.js

@@ -280,7 +280,7 @@ cutButton.addEventListener('click', () => {
                 cutPixelData[offset] = 255;       // red
                 cutPixelData[offset + 1] = 255; // green
                 cutPixelData[offset + 2] = 255; // blue
-                cutPixelData[offset + 3] = 0; // alpha
+                cutPixelData[offset + 3] = 255; // alpha
                   
             }
             else {
@@ -288,7 +288,7 @@ cutButton.addEventListener('click', () => {
                 cutPixelData[offset] = 0;       // red
                 cutPixelData[offset + 1] = 0; // green
                 cutPixelData[offset + 2] = 0; // blue
-                cutPixelData[offset + 3] = 0; // alpha
+                cutPixelData[offset + 3] = 255; // alpha
             }
         }
         cutContext.putImageData(cutPixelData, 0, 0);