Photoshop Tutorials -- More Advanced Masking Techniques made simple
More Advanced Masking Techniques with Photoshop
This Photoshop tutorial builds on the previous one that you can read here. If you haven't read that tutorial you can still follow along, but it would be best if you start out with a selection saved as a channel. If you're not sure what that's all about head back to the previous tutorial... for the rest of you, let's get started.
NOTE: This Photoshop lesson was created using Adobe Photoshop CS2, but the same results can be achieved in just about any version of Adobe Photoshop.
If you followed the previous tutorial you should have something like what you see in figure 21.1. That is, you should have an image that contains a channel with your saved selection that was created using Photoshop's quick mask.
Now that you have created and saved your selection you can do a number of things with your image using that selection. For example, you could copy and paste the selected area back into the original photograph. Doing so with the photo of the flamingoes would mean that I could introduce many 'new' birds into the picture (pardon the pun). Before we play around with the image and its mask, though, let's have a little more fun playing with the newly created channel.
Note that the channel contains a grayscale representation of your selection. Where the channel is white, the corresponding area of your photo would be selected if you created a selection from the channel. Parts of the channel that are black would not be selected. You can see then that the channel in figure 21.1 holds the required info to create a pretty good selection around the foremost flamingo in the photo.
Okay, but I said "grayscale", so what if there was some gray in the channel along with the black & white, you ask. Good question. Let's use 50% gray as an example. First I'll copy the channel that has my saved selection in it. To do so I simply dragged-n-dropped the channel in the Channels palette (choose Window, Channels to open the Channels palette) onto the Create new channel icon which can be found along the bottom of the palette (it resembles a small page with the corner turned in). Having done so, I can now work without worrying about the original channel getting accidentally (and irrevocably) toasted.
With the new copy of the channel active, I filled the white area with 50% gray. To do so < I clicked the Foreground color swatch in the toolbar and set the color to 50% gray. I then selected the Paint Bucket tool and clicked in the white area.
Next I created a selection from the channel by clicking the Load Channel as Selection icon in the bottom-left corner of the channels palette.
With the selection made, I activated the Layers palette and selected the Background layer (for now, it's the only layer in the image). I then chose Edit, Copy and I then activated an image that already has a copied selection of the flamingo (created using a selection made from the original channel) and chose Edit, Paste to paste in the newly copied bird (see figure 21.2).
You can see that the new copy (on the right in figure 21.2) is a ghost of the original. Actually, it's 50% as opaque as the original. What happened? The 50% gray is what happened. With the area filled in with gray instead of pure white, the bird was only 50% selected. You can, in fact, see the text right through the bird.
So what does this mean in real-world Photoshop terms? Well, it means that you could, for example, run a Gaussian Blur filter on the channel and soften the edges (which will become a mix of the black and the white, i.e. gray values). This would be similar to "feathering" a selection. but you have much more control applying the blur to the channel. You could, for example, make a selection within the channel and apply the blur only to that portion of the selection... selective feathering, if you will.
Expanding and Contracting:
Another trick that you can do with the channel containing your saved selection is to modify it such that the selected area (the white portions of the channel) expands or contracts. This is a fairly cool, high-level trick that uses the Maximum and Minimum filters. If you're going to follow along with a channel that you've created, make sure that you do so on a duplicate by copying the channel as I outlined above.
To contract the white area, (what will later become your selection) make sure that the channel you want to work on is active and then select the entire channel by choosing Select, All, and then choose Filters, Other, Minimum...
Doing so will open the Minimum dialog box. The Minimum dialog box has only one control... a slider. That slider will indicate, in pixels how much you're contracting the selection.
Figure 21.3 shows the original selection and a selection that was contracted by 2 pixels and subsequently had a 5 pixel Gaussian Blur applied to soften the edges.
You can expand the white area the same way by choosing Filter, Other, Maximum. Each pixel you set on the slider will expand the white area by the same distance. You can expand (or contract, for that matter) between 1 and 100 pixels.
Other Tricks You Can Try:
I mentioned earlier that you could select a portion of the channel and work on just that area. But you can do many things, you could, for example, use the Blur or Smudge tools (see figure 21.4) to soften areas of the channel. The result will be a very tailored selection. Don't be afraid to play around and explore what can be done with the channels you've created.
That's it for now... The next tutorial demonstrates how to adjust the exposure of a portion of a digital image using a mask as part of the technique. In the meantime be sure to check out some of our other Photoshop tutorials.
Everyone loves a quickie, especially if the quickies are free Quick Tip Videos for Photoshop. Our "Quickies" are short, web-based videos (approx. 2 minutes, or less) that highlight some neat trick or time-saving tip for Adobe Photoshop. Go ahead and check them out... you know you want to :)
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