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Over the past couple of columns, we've looked
at selections and masks – what they are and how they work. This
week, we'll explore creating and editing masks by working with
the various tools and commands that allow you to take advantage
of all 256 levels of "masked." To start,
let's create a practice file that we'll use throughout these
exercises. (It will be easier to follow these exercises if you
first open the Preferences> Units & Rulers, and set the Ruler
unit of measure to pixels.) Open a new Photoshop document, 350
pixels by 350 pixels, 72 pixels per inch, RGB color mode, filled
with white. In the Layers palette, click on the New Layer
button. Now open the color palette and change your foreground
color to R:255, G:255, B:0. Use the Paint Bucket to fill the new
layer with this yellow. Next, use Filter> Noise> Add Noise. Use
the settings 150%, Uniform, and make sure that Monochromatic is
checked. Your image and Layers palette should look like those
pictured here.
Next, pop up to the History palette and click on
the New Snapshot button at the bottom of the palette to create
Snapshot 1. We'll be starting over regularly during these
exercises ... but there's no need to got all the way back to a
blank file. The History palette should look like this:
For the first exercise, select the elliptical
marquee tool in the Toolbox. In the Options Bar (Photoshop 6) or
the Options palette (Photoshop 5 & 5.5), set Feather to 0 and
uncheck the anti-alias option. Elect the Constrained Aspect
Ratio option and make sure that it is set to Height 1, Width 1.
Drag a circular selection. With the rulers
visible, I dragged from 50,50 to 300,300. You don't need to be
precise – any circular selection that covers a large area of the
canvas is fine. Now press Q on the keyboard or click the Quick
Mask Mode button at the bottom of the Toolbox. In Quick Mask
mode, the image should look like this:
You see that the selection has defined a mask.
The mask has crisp, sharp edges, as seen by the definite break
between the red overlay and the unprotected area of the image. A
close-up:
If you zoomed in, return to 100% zoom. Exit
Quick Mask mode by pressing Q on the keyboard or clicking the
Standard Mode button in the Toolbox. Use the command Select>
Deselect or press Command-D (Mac) or Control-D (Win). Go to the
Options Bar or palette and add feathering to the Elliptical
Marquee. Type in 25 (or, if your unit of measure for the rulers
is not pixels, type in 25 px). Drag the same circular marquee as
in the previous example. Again, enter Quick Mask mode. Your new
mask should appear similar to that shown here:
We'll zoom in to 500% again. Compare the earlier
zoom with this one. Notice, first, that rather than a sharp,
clean division between masked and unmasked, the red overlay
fades. Looking at the rulers visible in each image, you'll see
that the same area of the canvas is shown.
If we return to 100% view, exit Quick Mask mode,
and hit Delete, the selection's feathering (shown in the mask as
the gradual fade) results in partial deletion of some pixels.
Now that the relationship between selections and
masks has been reinforced, let's make some masks from scratch.
In the History palette, click on Snapshot 1 to return the image
to the state seen above in the first figure. (You should have
two layers, one filled with yellow with added noise.)
Enter Quick Mask mode. Press D on the keyboard
or use the icon in the Toolbox to return your colors to black
and white. Select the Gradient tool and, in the Options Bar or
palette, choose a black-to-white linear gradient. Drag the
gradient from left to right. You'll create a mask similar to the
one shown by the red overlay here:
Exit Quick Mask mode and look at the resulting
selection. Observe that it seems to encompass only half of the
image. The pixels contained within the selection marquee are
selected at least 50% – whatever filter or command is applied
will be at least 50% effective on those pixels. Let's see what
happens when we hit Delete.
Note that, like the feathering seen earlier, the
deletion is only partially applied to some pixels.
Return to Snapshot 1 in the History palette and enter Quick Mask
mode again. Use the Lasso tool to drag a selection. With the
foreground color still set to black, use the Paint Bucket to
fill the selection. Drag the Eraser tool across the middle of
the selection. The mask may (or may not) look similar to this:
Exit Quick Mask mode and hit Delete. You'll get
an image comparable to this:
Again, click on Snapshot 1 in the History
palette and enter Quick Mask mode. Use the Paint Bucket to fill
the image with the red overlay. Apply the command Filter Render>
Clouds. Exit Quick Mask mode and hit Delete. Your clouds are
likely to differ from these, but the general idea is the same –
the filter was applied to the mask, changing the way in which
the mask created a selection.
Snapshot 1; Quick Mask mode – back to our
original test image. Use the Paint Bucket to fill the image with
a mask. Next, Filter> Noise> Add Noise. The settings should
still be those we used earlier. Click OK. Filter> Blur> Motion
Blur. Set the angle to 0 degrees and the distance to 9 pixels.
Click OK. Filter> Stylize> Emboss. The Angle can be 135 degrees,
the Height should be about 10 pixels, and the Amount can be set
to 300%. Click OK. Exit Quick Mask mode and hit Delete. Press
Command-H (Mac) or Control-H (Win) to hide the edges of the
selection to get a better look at the result.
Press Command-Z (Control-Z) to Undo. (Remember
that the selection edges are hidden but the selection remains
active.) Apply Filter> Blur> Motion Blur, using the settings
Angle: 34 degrees, Distance: 30 pixels. Notice that the areas
outside the selection borders are untouched, while the Motion
Blur has been applied with varying effect in the rest of the
image.
Return yet again to Snapshot 1 and enter Quick
Mask mode. Use the Paint Bucket, with the foreground color still
set to black, to fill the image. Filter> Stylize> Tiles is what
we'll use next. Set the number of tiles to 10, the maximum
offset to 10%, and elect to fill with the background color.
Click OK. Next, head for Filter> Sketch> Bas Relief. The setting
should be Detail: 7, Smoothness: 5, with the light coming from
the top left. Click OK. Exit Quick Mask mode. Choose Filter>
Pixelate> Crystallize. Pick a cell size of 50. Click OK.
Hide the edges with Command-H (Control-H), and
notice how, yet again, the mask has protected some areas, while
allowing the rest of the image to be filtered.
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