#computer color is broken

Sometimes when blurring colors in Photoshop, such as green and red, the transparent edges turn into this ugly dark sludge. This happens because your gamma is not turned on in your Color Settings. Here is an example: 

Check out how in gamma, the edges fade into a yellow instead of a blackish color. Nice, huh? Just go to Edit>Color Settings, check the box with ‘Blend RGB Colors Using Gamma”, and you’re good to go!