Lesson G: Saving & Loading Selections

Selection to Channel

Some selections take a while to make, and sometimes we discover we need them again. Luckily there is a way to store them and bring them back to life.

• Reopen the document called “F G color range.psd.”

In that document, we made a precise selection of everything except the sky pixels and used that selection to make a masked adjustment. That mask can get us that selection again!

• Hold down the ⌘/Ctrl key and click on the adjustment layer’s mask. You’ve got marching ants again.

How? Photoshop covertly keeps track of mask pixels in the Channels panel. Let’s have a look.

• Click on the mask again with no keys held down. We have to be sure its layer is highlighted and the mask is targeted.
• Look at the Channels panel. If it’s not on screen, choose Window > Channels.

There’s an extra channel there beyond the color channels. We call those “alpha channels.” When a mask is targeted, Photoshop uses a channel to manage it. If you click the layer thumbnail rather than the mask’s, the RGB channel will be highlighted but the mask will be visible. Highlight a different layer and there’s no more alpha channel (unless that layer has a mask too).

These mask alpha channels come and go as their layers are and aren’t highlighted. You can store your own, less transient channels too.

• View the Layers panel and highlight the Background. Draw a selection with a marquee tool or the Lasso tool.
• Choose Select > Save Selection…. Note that you’re creating a new channel with a name of your choosing. Give it a name, then click OK.
• Deselect (⌘-D/Ctrl-D), then look at the Channels panel.

It doesn’t matter what layer is highlighted, this channel will always be available. So if you ever need that selection again, you can ⌘/Ctrl it. Go ahead, try it!

• Before moving on, be sure to click (just one regular click) on the RGB channel in case you’ve targeted some other.

What Quick Mask Really Is

• Make another selection with whatever tool you like. Then tap the Q key to access Quick Mask.

If you look at the Channels panel, you’d think you saved the selection as a channel, then highlighted both it and the RGB channel. When that is done, the channel’s black pixels are shown as a translucent color, usually red. The Quick Mask feature is like a fast, temporary version of this. Very fast (tapping a letter) and very temporary (tapping the letter again deletes the channel).

I usually use Quick Mask to view a complex selection and make sense of it. You could do other things. If you paint with white or black while in Quick Mask, you’re adding to or taking away from the selection (respectively)! That is, you can hit Q, B (for “Brush”), D (for “Default” colors), and maybe X (to “eXchange” those colors), then paint areas into or out of the selection, and then hit Q to get back to the normal world again.

This is pretty esoteric stuff these days, but I wanted to be the one to tell you about it. I didn’t want you hearing about this workflow on the street. We now “paint” selections in the Select and Mask workspace (there’s a Brush tool there).

Luminosity Masks

I want to give you a final tip involving channels. The objective here is to brighten the darker areas without blowing out the light ones. More precisely, we’re going to make an adjustment whose strength is inversely proportional to the image’s luminosity.

• Open “G luminosity mask.psd.”
• ⌘/Ctrl-click on each color channel, noticing that you get a selection each time.

That’s right, getting a selection from a channel isn’t limited to alpha channels. Where a channel is white, that area will be fully selected. Where it’s black, it’s not selected at all. Grays yield areas that are partially selected: the more that’s selected, the lighter the gray. Phrased differently, the selection is proportional to the luminosity of the channel.

• ⌘/Ctrl-click on the RGB channel. You now have a selection that is proportional to the luminosity of the image. That is, the snow is the most selected thing. We want the opposite.
• Choose Select > Inverse. Now the snow is the least selected stuff.
• Create a Curves adjustment by clicking its icon in the Adjustments panel. Move the white-point slider in (leftward), noting that the highlights don’t lose much at all. Push the middle of the curve up a bit, too, to give even more light to the metal fish, again without impacting the snowy parts of the image.
• Save, marvel a bit, then close the document.