Let's Try GIMP! Lesson 7: Quick Mask & Colorize

Today we'll be working on selection using the Quick Mask tool. We discussed the layer mask back in Lesson 2, and this tool works similarly.

First, of course, I open my image of choice.

I then choose the Free Select tool (Toolbox-top row, third from the left, icon shaped like a lasso). By clicking and holding down the left mouse button and dragging the cursor, I can roughly select an area of the image; the boundary is represented by the dotted line.

Next, I use the tiny, almost-invisible icon in the bottom left corner of the screen (indicated above with a red arrow) to toggle the Quick Mask on. The Quick Mask will only turn on if you have already selected part of the image.

Whoa! The areas in red are the unselected part of the image. This makes it a lot easier to see, but, even better...

 ...There's another purpose to the mask: we can "paint" it to get a much more precise selection than any of the standard Select tools allow. (Note the selection of the Paintbrush tool.) The mask reacts only to Black and White.

Black paint increased the nonselected space; above, I'm using it to neaten up the edge of the pant leg and getting rid of the blank area next to it.
White increases the selected area; it's like erasing the "red" spaces. This allows you to correct if you make a mistake.

As you can see, by alternating between the two, I've successfully managed to get Kingpin's pants selected. Unfortunately, I can't do anything else while the Quick Mask is enabled, so it's back to the teeny little icon (remember?) to shut it off.

There. Back in Normal view, we can see the dotted selection lines and actually interact with the selection. Yay!

Because I'm paranoid, I'm going to copy the selection...

...and paste it as a new layer.

Kingpin has two pairs of pants now. He can certainly afford it.

Changing the color of those puppies was the whole point of this exercise, so I'm going to right-click and navigate the menus to the "Colorize" option.

Playing with the toggles makes the color shift. I want it to look a bit closer to grey than to purple.

Finally, I choose the Move tool (Toolbox, second row down, rightmost, looks like a blue cross with pointy ends). Clicking with the left mouse button and dragging, I tug the new pants over on top of the old ones until it all lines up.

And there we have it!