|Adobe Photoshop Basics|
We continue our lesson on selections with Quick Mask Mode and Alpha Channels. There's a reason we're discussing these two things together, because they are very similar to work with. Later, when you learn about layers, these same principles can be applied for working with layer masks and adjustment layers. (Continued below...)
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You can think of a mask or an alpha channel as a more visual way to represent a selection. Think back to earlier in this lesson when you used the feather command on a selection to create a soft vignette effect. You could use numeric values for the feathering amount, but there was no way to see the results of the feathering until you deleted the background.
Let's get an introduction to Quick Mask mode by creating a vignette effect a different way. Open an image and make an elliptical selection.
The Quick Mask buttons appear directly under the color palette on the toolbox. The shortcut key for Quick Mask is Q and this acts as a toggle to turn Quick Mask Mode on and off.
After making your elliptical selection, tap the Q key to switch to Quick Mask mode. The non-selected areas of the image are visible through a red screen.
The red shading indicates the masked (or non-selected areas). Now we want to feather the selection to create the vignette effect... but, what's this? The Select > Feather command is disabled. No fear... instead of feathering the selection, we can use the Gaussian Blur filter to get the same results. The difference is, we'll be able to see those results in real time.
Go to Filter > Blur > Gaussian Blur. You may need to click and drag in the small preview area to bring the edge of your image into view. However, if you click the preview check box, you can preview the changes in your actual image.
Since we went into Quick Mask mode before invoking the Gaussian Blur filter, the effects are only applied to our mask.
Now drag the Radius slider up to a range between 10-20 pixels and observe the Quick Mask.
OK the Gaussian Blur dialog.
Tap the Q key to exit Quick Mask mode.
Invert your selection.
Fill with white.
While this may seem like more steps than using the feather command, it's better because you can get a pretty good idea if your blur amount was right before making any drastic changes. With the feathering method it may take a few tries since it's basically guess work and you won't know if you guessed right until you fill the background.
That was the quick intro; there's actually a whole lot more you can do with Quick Mask. But first, let's explore some of the Quick Mask options.
If you double click either of the Quick Mask buttons on the toolbox, you can change the options.
If you prefer the colored area to represent the selection instead of the mask you can change that here. If the default red overlay color isn't working for your image, you can click the color square to change it to something that works better. And finally, you can adjust the opacity of the overlay color. Feel free to experiment with these options on your own.
Next > More Quick Mask Tricks