Working with masks in Photoshop

A reader asks:

In a Photoshop class I am taking I'm told to do the following: "What we want to do is leave the "hard" edge in the middle, but soften out the other areas. To do this, we will work with a soft brush at a flow of around 30-50%. Adjusting the flow is important; it will determine how smooth the transition will be. Switch back and forth between white and black (X key) to blend, but leave the hard edges of the dune, as adjusting them will give you a double shadow (not desirable). We'll be painting in the area circled in black to smooth the edges. After completing our masking, we will revert to the standard mode and add the resulting selection as a Curves adjustment layer."

I think I got the Quick Mask but then what?

Good Question:
When using the paint brush tool to "draw a mask" you use the paint brush tool to apply the mask to certain areas of your image that you want to either hide or reveal. Another use of the mask allows (or prevents) an effect, filter or adjustment to have an effect on portions of the image and not others.

This tool has four major settings. Flow is one of them. When you are working with masks, white and black become more symbolic. 100% white = 100% transparent mask, whereas 100% Black = 100% Opaque mask. Shades of gray = the continuum between transparent and opaque "coverings over the portion of the image."

Opacity:
You'll notice that the brush tool has two settings "Opacity" and "Flow". In a mask mode, the opacity will either load Bk, Wh, or gray into the brush. You can also load these shades into the brush using the color palettes on the bottom of the tool bar on the left side of the screen. If you want to swap the foreground color with the background all yo have to do is click "x" on the keyboard and they'll switch places. This is particularly helpful if you want to use Bk AND a shade of gray, for example. You can set these to shades into your foreground/background palette and toggle between them.

Flow:
The other setting for the Brush tool is "Flow". In it's most practical way of looking at it, this controls how feathered the edge will be when you paint with a 100% soft brush.

-E!