Hey Guys

I'm currently working a project and I'm afraid I've run into a bit of a conceptual road block.

What I'm trying to do is create a program which will allow the user to search flickr for images based on an input parameter, ie "dog" returns a list of images tagged as dog.

I've been able to get this portion of the code working thanks to the sketch by Brian Chung - http://www.bryanchung.net/?p=189

import proxml.*;

String userName = "";
String apiKey = "";
String nsid;
String url = "http://api.flickr.com/services/rest/";
String search = "panda";
XMLInOut xml = null;

void setup() {
 size(600,600);
 background(0);
 frameRate(15);
 xml = new XMLInOut(this);
}

void draw() {
}

void mousePressed() {
 photoSearch(search);
 //search = "bill gates";
}

void photoSearch(String _n) {
 String rest = url+"?method=flickr.photos.search";
 rest += "&api_key=" + apiKey;
 rest += "&text=" + search;
 xml.loadElement(rest);
}

void pandaPhotos(String _n) {
 String rest = url+"?method=flickr.panda.getPhotos";
 rest += "&api_key=" + apiKey;
 rest += "&username=" + _n;
 xml.loadElement(rest);
}

void interestingness(String _n) {
 String rest = url+"?method=flickr.interestingness.getList";
 rest += "&api_key=" + apiKey;
 rest += "&username=" + _n;
 xml.loadElement(rest);
}

void findByUsername(String _n) {
 String rest = url+"?method=flickr.people.findByUsername";
 rest += "&api_key=" + apiKey;
 rest += "&username=" + _n;
 xml.loadElement(rest);
}

void getPublicPhotos(String _n) {
 String rest = url+"?method=flickr.people.getPublicPhotos";
 rest += "&api_key=" + apiKey;
 rest += "&user_id=" + nsid;
 xml.loadElement(rest);
}



////////////////////////////////////////////////////

//               xmlEvent funcitons              //

////////////////////////////////////////////////////


void xmlEvent(proxml.XMLElement _x) {
 parseXML(_x);
}

void parseXML(proxml.XMLElement _x) {
 String stat = _x.getAttribute("stat");
 if (!stat.equals("ok")) {
   println("Error from Flickr");
   return;
 }
 proxml.XMLElement node = _x.getChild(0);
 String type = node.getName();
 if (type.equals("user")) {
   nsid = node.getAttribute("nsid");
   println(nsid);
   getPublicPhotos(nsid);
 }
 else if (type.equals("photos")) {
   int num = node.countChildren();
   println(num);
   getPhotos(node);
 }
}

void getPhotos(proxml.XMLElement _n) {
 int cnt = _n.countChildren();
 cnt = min(cnt,64);
 for (int i=0;i<cnt;i++) {
   proxml.XMLElement ph = _n.getChild(i);
   String fm = ph.getAttribute("farm");
   String sv = ph.getAttribute("server");
   String id  = ph.getAttribute("id");
   String sc = ph.getAttribute("secret");
   String imgURL = "http://farm"+fm+".static.flickr.com/"+
     sv + "/" + id + "_" + sc + "_s.jpg";
   PImage img = loadImage(imgURL);
   int x = (i%8) * img.width;
   int y = (i/8) * img.height;
   image(img,x,y);
 }
}

In my sketch I'd like to take the PImages created in void getPhotos(proxml.XMLElement _n) and store them into an array from which I could then theoretically compare the pixels in each image to create an "averaged" image.

This is where I'm running into trouble. I'm not really sure how to compare the pixels from a PImage array.

Here is what I've written so far-

void getPhotos(proxml.XMLElement _n) {

 int cnt = _n.countChildren();
 cnt = max(cnt,64);
 for (int i=0;i<cnt;i++) {
   proxml.XMLElement ph = _n.getChild(i);
   String fm = ph.getAttribute("farm");
   String sv = ph.getAttribute("server");
   String id  = ph.getAttribute("id");
   String sc = ph.getAttribute("secret");
   String imgURL = "http://farm"+fm+".static.flickr.com/"+
     sv + "/" + id + "_" + sc + "_s.jpg";

// new stuff

   PImage[] img = new PImage[_n.countChildren()];
   //PImage img = loadImage(imgURL);

   for ( int j = 0; j< img.length; j++ ) {

     img[j] = loadImage(imgURL);

     // int dimension = (img[j].width*img[j].height);

     // nested forloop reads the RGB values for each pixel in img[j]

     for (int x = 0; x < img[j].width; x++) {
       for (int y = 0; y < img[j].height; y++) {

         int loc = x + y*img[j].width; // var to store the location of each pixel within the image

         float r = red( (img[j].pixels[loc]) );
         float g = green( (img[j].pixels[loc]) );  
         float b = green( (img[j].pixels[loc]) );
       }
     }
   }
 }
}

Accessing the RGB values of each pixel in a photo seems to make sense, but I'm not sure how to go about comparing the pixels of different images given the above method. Is there a better way to go about doing this? Any and all help would be most appreciated! Thanks!

Thanks Ramin, using one loop totally makes more sense. Each image called by flickr is just a thumbnail which is 75x75 pixels so that should definitely simplify things.

By compare I meant take a look at each pixel[i] in every image, and average the RGB values of each pixel[i] to its corresponding pixel in the other images.

So for each image thumbnail there are 5625 pixels, so I would like to compare the RGB data for pixel 1, in every image and then create an new "averaged" RGB value based off that data. Sorry if this doesnt really make sense, but does that help clarify?

Hey Ramin, Thanks again for the reply.

I'm not sure I quite understand what you mean. I'm relatively new to programming and I havent worked with PVectors yet so I'm a little confused on how I would structure this code. Do you think you could give me a little more in depth example of what you mean?

heres my initial stab at it which doesnt work -

     PImage[] img = new PImage[100];

     for ( int j = 0; j< img.length; j++ ) {
 
       img[j] = loadImage(imgURL);
       int numPixels = img[j].width*img[j].height;

       PVector[] sum = new PVector[numPixels];
       
         for (int k = 0; k < numPixels; k++) {    
           color c = img[j].pixels[i];
           sum[numPixels].add( red(c),green(c),blue(c) );
       }
         
         for (int h = 0; h < numPixels; h++) {
           
           sum[numPixels].div(numPixels);
           PImage AvgImg = new PImage(RGB,75,75);
           AvgImg.pixels[i] = color(sum[j].x,sum[j].y,sum[j].z);
           image(AvgImg, width/2,height/2);  
       }
     }
   }

I'm getting a Array Index Out of Bounds Exception: 5625 at- sum[numPixels].add( red(c),green(c),blue(c) );      

great thank you! this makes a lot more sense.