• Adobe Photoshop

  How can I use the Alpha Channel to make a mask?

  Posted by Milton Hockman on March 21, 2006 at 3:02 pm

  I am on PS 6.0

  I have a picture of a man in a background
  I want to cut him out of the background
  I do not want to delete the background that I cut out.
  I just want to mask it so if later i want to bring part of it back i can.
  I know i can create a mask on the layer and use the brush tool to paint out what I don’t want. But when i paint back on the background I have to guess where the edge of the man is.

  I thought there was a way to paint on the alpha channel itself to achieve this effect. A way that would show me Red where the mask is hiding what I don’t want to see.
  Then if i wanted to touch up the edge of the man, i could see through the Red to know where to paint.

  anyone know how to do this?

  Richard Harrington replied 20 years, 1 month ago 3 Members · 2 Replies
• 2 Replies

• 

  Isotrope

  March 24, 2006 at 8:58 pm

  Hi mr_gfx,
  since I’m not certain how you’re set-up is, I would suggest that you make a quick selection (Lasso, Ellipse, Rectangle,…) of a part that you want to keep.
  Now, press Q. You have just activated the QuickMask tool. Is the part you selected red? or is it the opposite?
  I find that some jobs are easier to work on with the Red on the outside, others with the Red on the inside. To revert to normal mode, just hit Q again.
  But how do I switch it? you might ask. Look at your main toolbar, right below the Front/Background letter, you’ll find it to the right (I am looking at CS2 but it is quite similar in 6, if I recall correctly). When you find the icon, double-click it. The options will appear. You can even change the Red to something else.

  Hope this helps,
  iso
• 

  Richard Harrington

  March 26, 2006 at 3:05 am

  Quick mask cannot be saved with document…

  Be sure to create a new channel in the channels palette (that’ll be the alpha)

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