[JAVA][Beginning Java 8 Games Development]

Chapter 5 ■ An Introduction to Game Design: Concepts, Multimedia, and Using Scene Builder
■ ■Tip I recommend that you use the PNG digital imaging format for your Java 8 games. This is a professional
image-compositing format, and your games will essentially be a real-time sprite-compositing engine, so you will need
to use PNG32 imagery.
PNG has two truecolor file versions: PNG24, which cannot be used in image compositing, and PNG32, which
carries an alpha channel used to define transparency.
I recommend PNG for your games because it has a decent image compression algorithm and because it is a
lossless image format. This means that PNG has great image quality as well as reasonable levels of data compression
efficiency, which will make your game distribution file smaller. The real power of the PNG32 format lies in its ability to
composite with other game imagery, using transparency and antialiasing (via its alpha channel).
Digital Image Resolution and Aspect Ratio: Defining Image Size and Shape
As you probably know, digital imagery is made up of 2D (two-dimensional) arrays of pixels (“pixel” stands for picture
[pix] element [el]). The sharpness of an image is expressed by its resolution, which is the number of pixels in the image
width (or W, sometimes referred to as the x axis) and height (or H, sometimes referred to as the y axis) dimensions.
The more pixels an image has, the higher its resolution. This is similar to how digital cameras work, as the more
megapixels in an image capture device (called a camera CCD), the higher the image quality that can be achieved.
To find the total number of image pixels, multiply the width pixels by the height pixels. For instance, a wide video
graphics array (VGA) 800 × 480 image contains 384,000 pixels, which is exactly three-eighths of a megabyte. This is
how you would find the size of your image, both in terms of kilobytes (or megabytes) used and height and width on
the display screen.
The shape of a digital image asset is specified using the image aspect ratio. Aspect ratio is the width:height ratio
for the digital image and defines the square (1:1 aspect ratio) or rectangular (also known as widescreen) digital image
shape. Displays featuring a 2:1 (widescreen) aspect ratio, such as 2,160 × 1,080 resolution, are now available.
A 1:1 aspect ratio display (or image) is always perfectly square, as is a 2:2 or 3:3 aspect ratio image. You might
see this aspect ratio on a smart watch, for instance. It is important to note that it is the ratio between these two width
and height (x and y) variables that defines the shape of an image or screen, not the actual numbers themselves.
An aspect ratio should always be expressed as the smallest pair of numbers that can be achieved (reduced)
on either side of the colon. If you paid attention in high school while you were learning about the lowest common
denominator, then an aspect ratio will be very easy for you to calculate. I usually do aspect ratio calculation by
continuing to divide each side of the colon by two. For example, if you take the SXGA 1,280 × 1,024 resolution, half of
1,280 × 1,024 is 640 × 512, and half of 640 × 512 is 320 × 256; half of 320 × 256 is 160 × 128, half of that again is 80 × 64,
half of that is 40 × 32, and half of that is 20 × 16; half of 20 × 16 is 10 × 8, and half of that gives you the 5 × 4 aspect ratio
for SXGA, which would be signified by using a colon between the two numbers, as in a 5:4 aspect ratio.
Digital Image Color Theory and Color Depth: Defining Precise Image Pixel Colors
The color values for each digital image pixel can be defined by the amount of three different colors, red, green, and
blue (RGB), which are present in different amounts in every pixel. Consumer electronics display screens leverage
additive colors, in which wavelengths of light for each RGB color channel are added together creating 16.8 million
different color values. Additive color is used in liquid crystal display (LCD), light-emitting diode (LED), and organic
light-emitting diode (OLED) displays. It is the opposite of subtractive color, which is used in printing. To show you the
different results, under a subtractive color model, mixing red with green (inks) will yield purple colors, whereas in an
additive color model, mixing red with green (light) creates a vibrant yellow coloration. Additive color can provide a
much broader spectrum of colors than subtractive color.
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