Fairey posters (posterizing)

[Unpredictableimp]

i need help in posterizing. the project is basically turning a picture into something similar to the obama hope poster. i finished the border and the hope lettering, but i am lost as far as how i'm supposed to change the color of the picture.

#include <iostream>
#include "csufmedia.h"
#include <cmath>
using namespace std;

int main() 
{
  load_canvas("donuts.ppm");

  int x, y; 
  for (x = 0; x < canvas_width(); x++)  // loop through every x coordinate
  {
    for (y = 0; y < canvas_height(); y++)  // and through every y coordinate
	{

      // get the red, green, and blue intensities for the pixel at
      // coordinate (x, y)
      double r = get_red(x, y),
	g = get_green(x, y),
	b = get_blue(x, y);

      // compute new RGB intensities
      double new_r = 1 - r, // Inversion. You will need different code here
	new_g = 1 - g,      // to do posterization.
	new_b = 1 - b;

	 
      // Update the color of the pixel in the canvas.
      set_pixel(x, y, new_r, new_g, new_b);
    }
  }

   
  // border
 rectangle(0, 0,   // left side
	    10, 1024,       // width: 10 pixels, height: 1024 pixels
	    .99, .89, .65); // beige

 rectangle(802, 0,   // right side
	    10, 1024,       // width: 10 pixels, height: 1024 pixels
	    .99, .89, .65); // beige

 rectangle(0, 0,   // top
	    812, 10,       // width: 812 pixels, height: 10 pixels
	    .99, .89, .65); // beige

 rectangle(0, 1014,   // bottom
	    812, 10,       // width: 812 pixels, height: 10 pixels
	    .99, .89, .65); // beige

 //rectangle
 rectangle(10, 914,   // bottom
	    792, 100,       // width: 792 pixels, height: 100 pixels
	    0, .19, .30); // navy

 // H in hope
 rectangle(327, 924,   // right leg
	    10, 80,       // width: 10 pixels, height: 80 pixels
	    .44, .59, .62); // light blue

 rectangle(287, 959,   // middle
	    40, 10,       // width: 40 pixels, height: 10 pixels
	    .44, .59, .62); // light blue

 rectangle(277, 924,   // left leg
	    10, 80,       // width: 10 pixels, height: 80 pixels
	    .44, .59, .62); // light blue

  // O in hope
  vertical_semicircle(387, 924,   // right side
		      30,       // inner radius: 30 pixels
		      40,       // outer radius: 40 pixels
		      true,     // make it leftward
		      .44, .59, .62); // light blue

   vertical_semicircle(347, 924,   // left side
		      30,       // inner radius: 30 pixels
		      40,       // outer radius: 40 pixels
		      false,     // make it rightward not leftward
		      .44, .59, .62); // light blue

   // P
   rectangle(437, 924,   // leg
	    10, 80,       // width: 10 pixels, height: 80 pixels
	    .44, .59, .62); // light blue

   vertical_semicircle(447, 924,   // half circle of P
		      20,       // inner radius: 20 pixels
		      30,       // outer radius: 30 pixels
		      true,     // make it rightward not leftward
		      .44, .59, .62); // light blue

   // E
   rectangle(487, 924,   // leg
	    10, 80,       // width: 10 pixels, height: 80 pixels
	    .44, .59, .62); // light blue

   rectangle(497, 959,   // top
	    30, 10,       // width:30 pixels, height: 10 pixels
	    .44, .59, .62); // light blue

   rectangle(497, 924,   // middle
	    30, 10,       // width: 30 pixels, height: 10 pixels
	    .44, .59, .62); // light blue

   rectangle(497, 994,   // bottom
	    30, 10,       // width: 30 pixels, height: 10 pixels
	    .44, .59, .62); // light blue

  save_canvas("donuts2.ppm");

  return 0;
}

that's what i have so far.

 int x, y; 
  for (x = 0; x < canvas_width(); x++)  // loop through every x coordinate
  {
    for (y = 0; y < canvas_height(); y++)  // and through every y coordinate
	{

      // get the red, green, and blue intensities for the pixel at
      // coordinate (x, y)
      double r = get_red(x, y),
	g = get_green(x, y),
	b = get_blue(x, y);

      // compute new RGB intensities
      double new_r = 1 - r, // Inversion. You will need different code here
	new_g = 1 - g,      // to do posterization.
	new_b = 1 - b;

	 
      // Update the color of the pixel in the canvas.
      set_pixel(x, y, new_r, new_g, new_b);
    }
  }

was given by the professor and we have to change it around to posterize the picture, that's where i'm stuck...

[cpscnewb]

Hey Im in your class, and I was wondering if the dimensions have to be changed for every picture?

[gghf]

cpscnewb stop changing to different ones mannn just tel me if you finished the posterization so ill show you how to do the rest if you show me the posterization

[cpscnewb]

If i had the posterization code Id give it to you, lol

[gghf]

wowowowow i guess ill just do it then since nobody is helping

[cpscnewb]

.

[gghf]

in the sample code he gave us he uses for loops (nested) so I think it will be easier to do it that way

[cpscnewb]

the for loops are to count the pixels

[gghf]

wait so do we need to put anything between the nested for loops? the teacher put a { there

[cpscnewb]

yea thats where you put the if statements, but before the if statements you put the values that you calculate

[gghf]

hmm somethings telling me i might have to use arrays because they are good at comparing the closest things... i think

[gghf]

or was this assigned before we learned about arrays?

[cpscnewb]

.

[gghf]

ok i successfully ran the example code so ill see how far i can get by manipulating that

[cpscnewb]

it compiiled, my only problem is it's not reading the donuts ppm, for some reason

[gghf]

ok thanks but i noticed that you didnt use else if when you had a bunch of ifs but i guess that doesnt matter

[cpscnewb]

oh yeah i changed it right now to the last 3 ifs to be else if

[gghf]

actually i dont think it matters it ran perfectly thanks a lot man

[gghf]

im still going to try to figure it out bymyself though since i probably need to learn this

[gghf]

OH btw try to make sure that your code works for the elephant picture aswell, i dont think your letters are going to work for that