GMU:Processing im Park/Part1

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Image Basics

In the first part of this course you will learn the basics of working with images in your computer. Forget Photoshop and illustrator. You 've got the power!

Working with Images

Collecting Images

  1. Pick a topic from the big topic tombola
  2. Go to the Ilm-Park and take 100 photos in 45 minutes
  3. ???
  4. Profit

Programming Crash Course

Syntax

  • Processing uses Java Syntax
  • A Syntax Error means you got the spelling wrong, or you need to take some grammar lessons.
  • Processing is picky about missing semicolons.
  • Add a semicolon to the end of every line and you're fine (;

Functions

  • Function Calls:
    • function calls can take one or more function arguments given in round braces
    • function calls result in a value (or void)
    • functions can have side effects for example: drawing something on screen.
    • loadImage("park_001.png"); – calling a function to load an image
    • image(i, 0, 0); – calling a function to display an image
  • Examples
  • Functions Definitions:
    • define what argument a function takes (and which types those arguments have)
    • define what a function does
    • define what a function returns (and what type)
    • void draw() – tell the computer what to do to draw a single frame
    • void setup() – tell the computer what to do to set everything up.

Expressions

  • Any combo of numbers and mathematical operators
  • return a result
  • Can be used as argument to a function
  • can be assigned to a variable

Variables

  • In typed languages like Java every variable has a type
  • use variable declaration to tell the computer the variable exists
    • example: int i;
  • use variable definitions to assign a value to a variable
    • example: i = 1;
  • you can combine variable definition and declaration
    • example: int i = 1;'

Types

  • Number Types:
    • float – floating point (Real Numbers), i.e. 0.1, 1e10
    • int – Integer (Whole Number), i.e. 1, -100, 20000
    • byte – 8 bits (Number between -128 and +127)
  • Text Types
    • String – String (Sequence of Characters) i.e. "Processing im Park"
    • char – a single character, i.w. 'A' or 'a' or ' '

If this is all mumbo-jumbo to you, you better be quick, and start learning to code. Here is how to survive:

  1. If you love watching TV check out Dan Shiffmans Vimeo, or go to hello.processing.org (its just 1 hour!) – Highly recommended!
  2. If you prefer to learn by example check out OpenProcessing.org and Sketchbook.cc
  3. If you prefer to read a book, check out the Processing books.

Park Grid Sketch

Let's create our very first program!

  • Loads nine images from our data folde
  • display them in a 3x3 grid on screen
  • scale each picture to 100x100 pixels

Here's a screen shot:

 

Here's the source: 

// Pick the size of the canvas

size(300, 300);

// Let's load all the images from our sketchfolder

PImage image1 = loadImage("park_001.jpg");
PImage image2 = loadImage("park_002.jpg");
PImage image3 = loadImage("park_003.jpg");

PImage image4 = loadImage("park_004.jpg");
PImage image5 = loadImage("park_005.jpg");
PImage image6 = loadImage("park_006.jpg");

PImage image7 = loadImage("park_007.jpg");
PImage image8 = loadImage("park_008.jpg");
PImage image9 = loadImage("park_009.jpg");

// Display the images in a 3 by 3 grid

image(image1, 0, 0, 100, 100);
image(image2, 100, 0, 100, 100);
image(image3, 200, 0, 100, 100);

image(image4, 0, 100, 100, 100);
image(image5, 100, 100, 100, 100);
image(image6, 200, 100, 100, 100);

image(image7, 0, 200, 100, 100);
image(image8, 100, 200, 100, 100);
image(image9, 200, 200, 100, 100);

// Save a screen shot to the sketch folder

saveFrame("park_grid.jpg");

Interactive Park Sketch

Our very second program ;)

  • Load two images from our data folder
  • Switch between the images every second frame
  • Learn about the power of % a.k.a. modulo a.k.a. division with rest
  • Learning to use Flow control (the if else command)

Here's a screen shot:

 

Here's the source: 

PImage grid;
PImage tree;

void setup() {
  size(300, 300);
  background(0, 0, 0);
  grid = loadImage("park_grid.jpg");
  tree = loadImage("park_010.jpg");
  frameRate(5);
}

void draw() {

  if (frameCount % 2 == 1) {
    // show grid for odd frames
    image(grid, 0, 0);
  } else {
    // show tree for even frames
    image(tree, 0, 0, 300, 300);
  }
  
}

Homework 1

  • Create a sketch that loads 9 images
    • (feel free to recycle code from our first program)
  • Make the sketch flip through all nine images to create a slideshow / animation
    • Feel free to take inspiration from our second program

Cut-Ups, Pixels, Stripes, Collages

This part was about how to create cut-ups, interactive photo puzzles and collages.

Cut-Ups

In this part we will learn how to:

  • use arrays to work with lots of images
  • use loops to let the computer do repetetive tasks
  • create image collages
    • cut up images into stripes and squares
    • rearrange stripes and squares

Here's the source code for s simple 3x3 puzzle. We are cutting the original images into 9 parts, and rearrange them: 

PImage img;
PImage[] parts = new PImage[9];
int d;

void setup() {
  
  size(300, 300);
  d = width / 3;
  
  img = loadImage("photo.jpg");
  image(img, 0, 0, 300, 300);
 
  
  // get the parts
  for(int i=0; i<9; i++) {
    int x = (i % 3) * d;
    int y = (i / 3) * d;
    parts[i] = get(x, y, d, d);
  }
   
}

void draw() {
  
  background(0);
  
  for(int i=0; i<9; i++) {
    int x = (i % 3) * d;
    int y = (i / 3) * d;
    image(parts[8-i], x, y);
  }
  
}

Here's the final version, that uses variables, arrays and loops to allow for arbitrary number of tiles: 

PImage img;

// tiling parameters
int columns = 5;
int rows = 5;
int tiles = columns * rows;

// change this to show/hide the labels ontop of the tiles
boolean debugview = true;

// size of the labels
int labelWidth = 20;
int labelHeight = 20;

// array for the tiles
PImage[] parts = new PImage[tiles];

// dimensions of a single tile
int dx;
int dy;


void setup() {
  
  size(300, 300);
  
  // calculate dimensions of a single tile
  dx = width / columns;
  dy = height / rows;
  
  // load image and draw it on the canvas
  img = loadImage("photo.jpg");
  image(img, 0, 0, width, height);
  
  // extract the tiles from the canvas
  for(int i=0; i < tiles; i++) {
    
    // get tile coordinates
    int x = (i % columns) * dx;
    int y = (i / columns) * dy;
    
    // crop tile from the canvas
    parts[i] = get(x, y, dx, dy);
    
  }
  
  noLoop();
   
}

void draw() {
  
  for(int i=0; i < tiles; i++) {
    
    // get tile coordinates
    int x = (i % columns) * dx;
    int y = (i / columns) * dy;
    
    // cange the order of tiles by picking a different index (play with this!)
    
    //// invert indices
    // int index = tiles - i - 1;
    
    // pick a random index
    int index = int(random(tiles));
    
    // make sure the index does not get out of range ...
    index = index % tiles;
    
    // show the tile
    image(parts[index], x, y);
    
    // show grid ontop of the tiles
    noFill();
    rect(x, y, dx, dy);
    
    // just a quick hack to put a label ontop of each tile
    if(debugview) { 
      
      // draw white labels behind the numbers so we can read them better
      textAlign(CENTER);
      fill(255, 150);
      noStroke();
      rect(x +dx/2 -labelWidth/2, y +dy/2 -labelHeight/2, labelWidth, labelHeight);
      
      // draw numbers on tiles
      fill(0);
      text(index, x + dx/2, y+dy/2 + 5);
    }
    
  }
  
}

Homework 2

  • Pick an image from the link section below
  • Write a step by step instruction detailing the algorithm
  • Create a processing sketch that applies the algorithm to one of your photos.

Things to keep in mind:

  • Don't tweak my sketch, start from scratch
  • Use comments, to explain your intention

Links

Collages

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