Because we used a duplicate layer, we still have the color image in the background layer. We are going to paint on a layer mask to reveal the color in the background layer below. If you've followed any of my previous tutorials, you may already be familiar with layer masks. For those that aren't, here's a recap:
A layer mask lets you erase parts of a layer by painting on the mask. White reveals the layer, black blocks it completely, and shades of gray partially reveal it. Because our mask is currently all white, the entire grayscale layer is being revealed. We are going to block the grayscale layer and reveal the color of the apples from the background layer by painting on the layer mask with black. You can learn more about how masks work in my article, All About Grayscale Masks.
