Processing: Creative Coding and Computational Art

PROCESSING: CREATIVE CODING AND COMPUTATIONAL ART
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blend() and filter()
There are two other powerful Photoshop-esque imaging functions in Processing’s toolbox:
blend() and filter(). These functions each do so much that they could easily have been
divided into a bunch of separate functions. They’re built upon some very low-level
coding—mostly using bitwise operations—and were developed as a group effort, with
considerable contributions by Karsten Schmidt (a.k.a. toxi) (www.toxi.co.uk/) and Mario
Klingemann (www.quasimondo.com/). If you’d like to take a look at the actual source
code implementation (to better appreciate toxi and Klingemann’s efforts), check out
Processing’s PImage class at http://dev.processing.org/source/index.cgi/trunk/
processing/core/src/processing/core/PImage.java?view=markup.
I do, however, have some (small) misgivings about these functions being included in
Processing, as they so deeply encapsulate very low-level processing, and—not unlike
Photoshop—can become easy targets for fast, uninformed effects. In this sense, I feel their
ease of use and power actually have the potential to limit creativity. For example, here’s a
sketch that uses the filter function to invert an image (see Figure 10-36). Please remember
to add an image into your data directory for all the examples prior to using loadImage(),
as in the previous examples.
// INVERT Filter
// image should be 600 x 400 pixels
size(600, 400);
background(255);
PImage img = loadImage("view.jpg");
image(img,0,0);
filter(INVERT);
Figure 10-36. INVERT Filter sketch