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Last week, Alexandro Colorado emailed me asking
why Photoshop creates a mask when making shapes with the shape
tool. I told him that I would explain the reason why the best I
could.
First let's start out with what Photoshop vector
shapes are. They aren't really vector shapes at all. In fact
they are a solid fill of color with a mask or clipping path over
the top of the color to make it appear as a vector shape. The
mask can be edited just like a vector shape is in Illustrator or
Freehand, which makes it appear as though the shape is a vector.
Let's start with a simple shape. This is a
rabbit that ships in the Photoshop shapes palette. As you can
see, it looks like any other rabbit you've seen.
Now take a look at the layers palette. On the
layer with the rabbit you see two things - a color portion and a
vector mask portion. The color portion can be changed in real
time just like a vector program does. When you double click on
the layer color swatch, a color picker appears. When you select
a color the entire shape is instantly converted to that color.
This is much nicer that selecting and filling a shape as you
would traditionally with a raster shape, since it leaves no halo
or jaggy leftovers after a few fill changes.
Let's look at the image up close.
Now that we are zoomed in, you can see that
Photoshop is smoothing the image boundaries just as would happen
with any other rasterized image. A true vector program would
allow you to zoom in as close as you could and you would still
see a perfectly smooth line. So this really isn't a vector shape
at all- it only appears to be in the way that Photoshop let's
you manipulate it.
So in the above image I have simply messed
around with the paths on the shape. Photoshop updates the shape
according to my changes in real time. I am really altering the
mask, but it appears as though I am altering the shape itself.
You can see the path around the image easily here.
In the above image I have selected a new color
which Photoshop again updates in real time. This is a nice
feature that keeps one from having to do a select-fill. It also
preserves the edges of the image much better than it would
otherwise.
So to answer your question Alexandro, the mask
is created so you can manipulate the image before you rasterize
it. It creates a vector-like shape that can be manipulated in
real time without loss of clarity. This is a real time-saver and
it allows you the freedom to make changes easily. I hope this
answers all of your questions. Talk to you all soon. |