Learning Processing: A Beginner's Guide to Programming Images ...

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void setup() { size(320,240); video = new Capture(this, width, height, 30); // Create an empty image the same size as the video backgroundImage = createImage(video.width,video.height,RGB); } void draw() { // Capture video if (video.available()) { video.read(); } loadPixels(); video.loadPixels(); backgroundImage.loadPixels(); We are looking at the video’s pixels, the memorized backgroundImage’s pixels, as well as accessing the display pixels. So we must loadPixels() for all! // Draw the video image on the background image(video,0,0); // Begin loop to walk through every pixel for (int x = 0; x < video.width; x + + ) { for (int y = 0; y < video.height; y + + ) { int loc = x + y*video.width; // Step 1, what is the 1D pixel location color fgColor = video.pixels[loc]; // Step 2, what is the foreground color // Step 3, what is the background color color bgColor = backgroundImage.pixels[loc]; // Step 4, compare the foreground and background color float r1 = red(fgColor); float g1 = green(fgColor); float b1 = blue(fgColor); float r2 = red(bgColor); float g2 = green(bgColor); float b2 = blue(bgColor); float diff = dist(r1,g1,b1,r2,g2,b2); // Step 5, Is the foreground color different from the background color if (diff > threshold) { // If so, display the foreground color pixels[loc] = fgColor; } else { // If not, display green pixels[loc] = color(0,255,0); We could choose to replace the } background pixels with something } other than the color green! } updatePixels(); } Video 295 void mousePressed() { // Copying the current frame of video into the backgroundImage object // Note copy takes 5 arguments: // The source image // x,y,width, and height of region to be copied from the source // x,y,width, and height of copy destination backgroundImage.copy(video,0,0,video.width,video.height,0,0,video.width,video. height); backgroundImage.updatePixels(); }
296 Learning Processing When you ultimately get to running this example, step out of the frame, click the mouse to memorize the background without you in it, and then step back into the frame; you will see the result as seen in Figure 16.10. If this sketch does not seem to work for you at all, check and see what “ automatic ” features are enabled on your camera. For example, if your camera is set to automatically adjust brightness or white balance, you have a problem. Even though the background image is memorized, once the entire image becomes brighter or changes hue, this sketch will think all the pixels have changed and are therefore part of the foreground! For best results, disable all automatic features on your camera. 16.7 Exercise 16-6: Instead of replacing the background with green pixels, replace it with another image. What values work well for threshold and what values do not work at all? Try controlling the threshold variable with the mouse. Motion Detection Today is a happy day. Why? Because all of the work we did to learn how to remove the background from a video gets us motion detection for free. In the background removal example, we examined each pixel’s relationship to a stored background image. Motion in a video image occurs when a pixel color diff ers greatly from what it used to be one frame earlier. In other words, motion detection is exactly the same algorithm, only instead of saving a background image once, we save the previous frame of video constantly! Th e following example is identical to the background removal example with only one important change— the previous frame of video is always saved whenever a new frame is available. // Capture video if (video.available()) { // Save previous frame for motion detection!! prevFrame.copy(video,0,0,video.width,video.height,0,0,video.width,video.height); video.read(); } (Th e colors displayed are also changed to black and white and some of the variable names are diff erent, but these are trivial changes.)
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Learning Processing A Beginner’s
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Learning Processing A Beginner’s
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Contents Acknowledgments vii Introd
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Acknowledgments In the fall of 2001
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Introduction What is this book? Th
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Introduction xi While both of these
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Introduction xiii Th e book is desi
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Introduction xv Th is book’s web
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Introductory Exercise: Write instru
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Lesson One The Beginning 1 Pixels 2
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1 Pixels “ A journey of a thousan
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1.2 Simple Shapes Pixels 5 Th e vas
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0 1 2 3 4 5 6 7 8 9 fi g. 1.9 top l
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1.3 Pixels 9 Exercise 1-3: Reverse
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Example 1-2: noFill ( ) background(
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fi g. 1.19 Pixels 13 Exercise 1-5:
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colorMode(RGB,100); Pixels 15 Th e
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2 2.1 Processing “ Computers in t
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fi g. 2.2 Once you have opened the
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Let’s write a fi rst example ( se
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Line 9 fi g. 2.6 Processing is case
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fi g. 2.7 Processing 25 Processing
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Example 2-1: Zoog again size(200,20
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Processing 29 To see the applet wor
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3 3.1 Interaction “ Always rememb
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Let’s look at what will surely be
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3.3 Variation with the Mouse Intera
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Draw Zoog's eyes fill(0); ellipse(8
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3.4 Mouse Clicks and Key Presses In
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Draw Zoog's eyes fill(mo useX,0,mou
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Lesson Two Everything You Need to K
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4 4.1 Variables “ All of the book
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4.2 Variable Declaration and Initia
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A variable can also be initialized
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x = 5; x = a + b; x = y - 10 * 20;
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void draw() { // Draw the backgroun
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4.6 Random: Variety is the spice of
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4.7 Example 4-7: Filling variables
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5 5.1 Conditionals Conditionals 59
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Finally, for testing multiple condi
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Conditionals 63 It is worth pointin
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Conditionals 65 Getting into the ha
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Our fi rst instinct might be to wri
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5.5 Multiple Rollovers Conditionals
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Conditionals 71 We can then check t
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5.7 Conditionals 73 Exercise 5-8: E
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Reversing the Polarity of a Number
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One way to solve this problem is to
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Display the square fill(0); noStrok
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6 Loops “ Repetition is the reali
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Loops 83 (see Chapter 5). However,
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while (y < 100) { // Loop! } 3. Wha
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while (x < = endLegs) { line(x,y,x,
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Th e same exact loop can be program
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Loops 91 Th is was a nice simplifi
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6.6 Loop Inside the Main Loop Loops
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6.7 float distance = abs(mouseX - i
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Draw Zoog's legs stroke(0); line(x-
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Lesson Three Organization 7 Functio
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7 7.1 Functions “ When it’s all
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7.2 “ User Defi ned ” Functions
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Example 5-6: Bouncing ball // Decla
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7.5 Functions 107 Exercise 7-3: Tak
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Functions 109 It should be fairly a
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int globalX = 0; int globalY = 100;
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void setup() { println( "a"); funct
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If we did not include a return stat
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7.8 Zoog Reorganization Zoog is now
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void draw() { } background(0); // D
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8 8.1 Objects “ No object is so b
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Setup: Draw: Initialize car color.
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Objects 125 • The Class Name—Th
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Objects 127 One other thing; with t
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fi g. 8.1 fi g. 8.2 fi g. 8.4 fi g.
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Objects 131 Nevertheless, this is q
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void draw() { } background(100); ba
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Objects 135 modular, reusable packa
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Lesson Three Project Step 1. Take y
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Lesson Four More of the Same 9 Arra
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9 Arrays “ I might repeat to myse
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Car myCar80 Car myCar81 Car myCar82
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9.3 Declaring and Creating an Array
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9.4 Initializing an Array One way t
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Example 9-5: Using a for loop to in
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Arrays 151 Now comes the hard part.
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9.7 Arrays 153 Exercise 9-7: Rewrit
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9.8 Interactive Objects Arrays 155
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Check if point is inside of Stripe
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alls[i].gravity(); balls[i].move();
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Draw Zoog's arms with a for loop fo
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Lesson Five Putting It All Together
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10 10.1 Algorithms “ Lather. Rins
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Translating the preceding algorithm
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void draw() { background(255); stro
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Example 10-2: Bouncing ball class c
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Now that the function is complete,
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10.6 // Constructor Ball(float temp
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Algorithms 177 With the above logic
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Drop() { r = 8; // All raindrops ar
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Example 10-7: Drops one at a time /
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Algorithms 183 Notice how every sin
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oolean intersecting = ball1.interse
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} void setLocation(float tempX, flo
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Algorithms 189 It is important to r
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11 Debugging “ Th e diff erence b
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Debugging 193 Once all the code is
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12 Libraries “ If truth is beauty
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or /Applications/Processing 0135/ c
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Lesson Six The World Revolves Aroun
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13 Mathematics Mathematics 201 “
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Mathematics 203 Th erefore, modulo
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Th e probability of a coin fl ippin
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13.6 Perlin Noise Mathematics 207 O
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Mathematics 209 How quickly we incr
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It is fairly intuitive for us to th
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fi g. 13.9 y-axis sine(theta) � y
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Example 13-6: Oscillation float the
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Mathematics 217 In 1975, Benoit Man
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Mathematics 219 said about recursio
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Mathematics 221 A two-dimensional a
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Example 13-10: Two-dimensional arra
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} void display() { } // FILL IN Mat
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14 14.1 Translation and Rotation (i
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Our fi rst instinct might be to add
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Example 14-3: A rectangle moving al
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When using the OPENGL mode, you mus
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Translation and Rotation (in 3D!) 2
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14.5 fill(150,150); vertex(-t, t,-t
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14.6 Example 14-5: Rectangle rotati
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Page 264 and 265: Translation and Rotation (in 3D!) 2
Page 266 and 267: fill(0,100); // Note the use of pus
Page 268 and 269: 14.9 Example 14-17: Nested push and
Page 270 and 271: stroke(0); fill(175); ellipse(0,0,d
Page 272 and 273: Lesson Seven Pixels Under a Microsc
Page 274 and 275: 15 Images Images 255 “ Politics w
Page 276 and 277: And yet: PImage img = loadImage( "f
Page 278 and 279: 15.3 My Very First Image Processing
Page 280 and 281: Images 261 Even better, if we just
Page 282 and 283: Images 263 // Create a grayscale co
Page 284 and 285: Images 265 15.6 Intro to Image Proc
Page 286 and 287: Images 267 Since we are altering th
Page 288 and 289: 15.9 More on fi lter( ): fi lter(mo
Page 290 and 291: Images 271 Example 15-13 performs a
Page 292 and 293: Example 15-14: “ Pointillism ”
Page 294 and 295: 16 16.1 Video “ I have no memory.
Page 296 and 297: Video 277 Th e above line of code i
Page 298 and 299: void draw() { // Check to see if a
Page 300 and 301: 16.3 Recorded Video Video 281 Displ
Page 302 and 303: 16.4 Video 283 Exercise 16-3: Using
Page 304 and 305: Video 285 For every square at colum
Page 306 and 307: } } // Each rect is colored white w
Page 308 and 309: 16.5 Video as Sensor, Computer Visi
Page 310 and 311: Now, we are ready to compare the co
Page 312 and 313: 16.6 Video 293 Exercise 16-5: Take
Page 316 and 317: Example 16-13: Simple motion detect
Page 318 and 319: 16.8 // Step 4, compare colors (pre
Page 320 and 321: Lesson Seven Project Develop a soft
Page 322 and 323: Lesson Eight The Outside World 17 T
Page 324 and 325: 17 17.1 Text “ I could entertain
Page 326 and 327: Exercise 17-2: Loop through and pri
Page 328 and 329: 17.3 Displaying Text Text 309 We wi
Page 330 and 331: println(PFont.list()); For demonstr
Page 332 and 333: X = �50 fi g. 17.4 float w = text
Page 334 and 335: Example 17-4: Text mirror import pr
Page 336 and 337: textFont(f); // Set the font transl
Page 338 and 339: Exercise 17-9: Using textWidth( ) ,
Page 340 and 341: Example 17-7: Boxes along a curve P
Page 342 and 343: Text 323 Exercise 17-10: Create a s
Page 344 and 345: 18 Data Input “ A million monkeys
Page 346 and 347: Example 18-1: User input PFont f; /
Page 348 and 349: Data Input 329 Th e reverse of spli
Page 350 and 351: Example 18-2: Graphing comma separa
Page 352 and 353: Data Input 333 Th e rollover( ) fun
Page 354 and 355: 18.4 diameter = diameter_; } // Tru
Page 356 and 357: } // Find the index of the end tag
Page 358 and 359: void mousePressed() { // Increment
Page 360 and 361: 18.6 for (int i = 0; i < kinglear.l
Page 362 and 363: Create and make an asynchronous req
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� student � � id � 002 �
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Requests for XML data are made via
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18.8 Using the Processing XML Libra
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XMLElement diameterElement = childr
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Example 18-10: A Yahoo search impor
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However, if you request a URL on a
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19 19.1 Data Streams “ I’m mad
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import processing.net.* ; Server se
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Data Streams 361 Once the server is
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19.4 void draw() { background(255);
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Data Streams 365 must be networked
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Data Streams 367 will send X , Y co
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Data Streams 369 Here is the full S
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Here is the entire client sketch: 1
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Data Streams 373 Serial communicati
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Data Streams 375 of information, ca
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Corresponding Arduino code: int sen
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Lesson Nine Making Noise 20 Sound 2
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20 Sound “ Check. Check. Check 1.
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void setup() { Sonia.start(this); }
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void mousePressed() { // If the use
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Sound 387 check and see if a sound
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Is a point inside the doorbell (use
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Pressing the mouse stops and starts
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20.6 void draw() { background(255,1
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In code, this translates to: // If
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21 Exporting “ Wait a minute. I t
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Th is code can be inserted anywhere
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void setup() { size(400, 400); begi
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Exporting 403 save( ) takes one arg
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Exporting 405 Example 21-5 records
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Lesson Ten Beyond Processing 22 Adv
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22 Advanced Object-Oriented Program
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class Point { float x,y; Point(floa
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Advanced Object-Oriented Programmin
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Advanced Object-Oriented Programmin
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class Circle extends Shape { // inh
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for (int i = 0; i < dogs.length; i
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22.5 Example 22-2: Polymorphism //
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23 23.1 Java “ I l o ve c off ee,
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Java 425 instead of Processing , sp
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fi g. 23.2 Java 427 Just as with th
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Particle p = parray[i]; p.run(); p.
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Hint: Add a function that returns a
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Example 23-4: Super fancy ArrayList
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Java 435 It is sad when these error
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Th e tutorials will cover the same
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Appendix: Common Errors Appendix 43
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Error: No accessible fi eld named
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void draw() { thing.display(); } Co
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Error: Perhaps you wanted the overl
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Index AIFF (Audio Interchange File
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Fill( ) function 10 , 11 , 256 , 30
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One-dimensional Perlin noise 208 OP
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solar system, processing 247-9 vert
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