[JAVA][Beginning Java 8 Games Development]

Chapter 5 ■ An Introduction to Game Design: Concepts, Multimedia, and Using Scene Builder
Masking can be done for you automatically, using professional blue screen (or green screen) backdrops, along
with computer software that can automatically extract those exact color values to create a mask, which is turned into
alpha channel (transparency) information (data). Masking can also be done manually, using digital image software,
via one of the algorithmic selection tools, in conjunction with various sharpening and blur algorithms.
You will learn a lot about this work process over the course of this book, using common open-source software
packages, such as GIMP. Masking can be a complex and involved work process. This chapter is intended to expose you
to foundational knowledge that will underlie the processes you undertake while working through the book.
A key consideration in the masking process is getting smooth, sharp edges around a masked object
(subject matter). This is so that when you place a masked object (in this case, a game sprite) into (over) new
background imagery, it looks as if it were photographed there in the first place. The key to doing this successfully lies
in your selection work process, which entails using digital image software selection tools, such as the scissors tool in
GIMP, or the magic wand tool in Photoshop, in the proper fashion. Choosing the correct work process is critical!
For instance, if there are areas of uniform color around the object that you wish to mask (maybe you shot it
against a blue screen), you will use a magic wand tool with a proper threshold setting to select everything except your
object. Then, you invert the selection, which will give you a selection set containing the object. Often, the correct
work process requires approaching something in reverse. Other selection tools contain complex algorithms that
can look at color changes between pixels. These can be useful for edge detection, which you can use for other
selection methods.
Smoothing Digital Image Composites: Using Antialiasing to Smooth Image Edges
Antialiasing is a popular digital image–compositing technique, in which two adjacent colors in a digital image are
blended together along the edge that borders the two color areas. This tricks the viewer’s eye into seeing a smoother
(less jagged) edge when the image is zoomed out, thereby eliminating what has come to be called image jaggies.
Antialiasing provides an impressive result by using averaged color values (a color range that is a portion of the way
between the two colors coming together), with just a few colored pixels along the edge that needs to be smoothed.
Let’s take a look at an example to see what I am talking about. Figure 5-2 shows what appears to be a razor-sharp
red circle on one layer, overlaying a yellow fill color on a background layer. I zoomed into the red circle’s edge and
then made another screenshot, placing it to the right of the zoomed-out circle. This screenshot reveals a range of
antialiasing color values (yellow-orange, to orange, to red-orange) right on the edge bordering the red and yellow
colors, where the circle meets the background.
Figure 5-2. A red circle composited on a yellow background (left) and a zoomed-in view (right) showing antialiasing
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