The Power of Gray - The Photoshop: Professional Retouching and Compositing Tips, Tricks, and Techniques - page 140

Figure 2.67
3. Adjust Brightness to 70% and click OK.
Now in Photoshop we can see that the lens flare has been added, but we can also
see the additional Photoshop flares ( Figure 2.68 ) . Depending on the look you are
after, you may not like to see these, but using 50% gray we are able to remove
them.