15 Step 15
Now create a new layer above the “Paint” layer and name it “Color.” Use the Gradient Tool, open the Gradient picker in the Tool Options and pick: Blue, Red, and Yellow. Set it to Linear Gradient and fill the layer as shown below. Hold down the Alt key and click the line between the “Paint” and “Color” layers to define the “Paint” layer as a Clipping Mask. Set the “Color” layer Blending Mode to Difference.
