Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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24-bit color value is literally just a 24-digit number, made up of zeros and ones, where the
first 8 bits are used for blue, the next 8 bits are used for green, and the last 8 bits are used
for red. If you raise 2 to the 24th power, you get the same answer as before: 16,777,216
possible colors. If you’ve ever used a control panel device to change your screen resolution,
you’ve probably seen 16.7 million colors—or just “millions of colors”—as a choice.
When I first got involved in computer graphics in 1992, it was common to have systems
that couldn’t handle 24-bit color, and you were forced to use either 16-bit or even 8-bit
color depths, which only permitted a range of 65,536 colors or 256 colors, respectively.
8-bit displays required fixed palettes composed of only 256 colors. 8-bit color is referred
to as indexed color, while 24-bit color is referred to as true color. Working in 8-bit color
space, we were forced to choose the 256 colors we wanted to use for a project, and it was
not easy to change the palette on the fly; it also didn’t help that Windows and Mac had
separate palettes. The web safe palette, which some of you might be familiar with, was one
such made-up palette. It only included 216 of the 256 colors common to both Mac and PC
platforms. These limited palettes led to pretty dithered images. Dithering occurs when colors
outside of the range of the palette need to be approximated, which is done through
the grouping of adjacent colors—optically mixing the necessary color. Dithering helps create
the illusion of a wider color gamut on an 8-bit system, but usually leads to pretty
grainy looking images.
Although contemporary monitors display 24 bits of information for each pixel, internally it
is possible to pack even more information into a pixel data structure. Photoshop, as an
example, supports 48-bit color, as do some scanners and digital cameras, allowing each
pixel to utilize 16 bits for each color component—that’s 65,536 unique values for each
red, green, and blue component, or a total of over 281 trillion (not a typo) different colors.
I know 281 trillion colors sounds bizarre, and nobody uses (or needs) all those colors,
but the additional color space supports an increased range of visual detail in areas like
shadows. Digital photographers especially benefit from the increased bit depth, as they
can combine numerous exposures into a single image, creating images with a higher
dynamic range than possible with traditional methods. 48-bit images are also utilized in 3D
as radiance maps for rendering composited images, in which a 3D, computer-generated
model is seamlessly blended into a photographic environment. The radiance maps work as
powerful sources of illumination in the rendering process.
Java’s BufferedImage class can handle 32 bits per pixel, and adds an additional 8-bit alpha
component to the RGB 24-bit structure. Alpha controls the translucency of the pixel, ranging
from 100 percent, which is opaque, to 0 percent, which is transparent. The integer data
type in Java and Processing is 32 bits in length, making it very convenient to store pixel values
as individual integers—holding red, blue, green, and alpha, commonly abbreviated as
RGBA. If your head isn’t spinning yet, you can see that, in spite of its complexity, the
BufferedImage class really handles a lot. And in spite of the complexity involved in using
it, coding graphics in Java would still be a lot scarier if you had to deal with all the mathematical
calculations and color transformations the BufferedImage class handles internally.
In contrast to using the BufferedImage class in Java, in Processing you can simply call two
or three functions to get some similar low-level access. Of course, you have less access and
flexibility than working in pure Java—but most of the stuff you really need or want to use
is available in Processing, so you really can have your cake and eat it too. As I mentioned
in earlier chapters, as you get deeper into graphics programming, Processing’s genius