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store rgb in a array. (Read 1682 times)

clankill3r

store rgb in a array.
Mar 26^th, 2009, 11:40am

Hi,

I want to store all the rgb values in a array by there x and y axis.
Only I don't know how to set the value for the length of the array, now I use this and it doesnt give a error, I this a good way or are there better ways?

Code:


//declare, create
float[][] r = new float[10000][];
float[][] g = new float[10000][];
float[][] b = new float[10000][];

PhiLho YaBB Moderator Offline Posts: 4190 Near Paris (France)	Re: store rgb in a array. Reply #1 - Mar 26^th, 2009, 12:01pm I don't understand your need. What RGB values? Where do they come? Are you aware, if that's the sketch's colors, that you have them already if you use loadPixels()?

clankill3r

Re: store rgb in a array.
Reply #2 - Mar 27^th, 2009, 3:48am

loadPixels won't work I guess cause I want to calculate average values and do something else. It's not for copying pixels, I want to use images as somekind of ponscard (don't now if it's the correct word).

so far I got this but it says 'cannot convert from float to int' on this line:
r[i][j] = get(i, j);

how do I fix that?

Code:

PImage img;

float[][] r = new float[5000][];
float[][] g = new float[5000][];
float[][] b = new float[5000][];

void setup(){
  size(50, 100);
  img = loadImage("plaatje.png");
  noLoop();
}

void draw() {
  image(img, -20, -20);
  for (float i = 0.0; i<width; i++){
    for (float j = 0.0; j < height; j++){
	r[i][j] = get(i, j);    
	//println(i + " " + j);  
    }
  }
}

Cedric YaBB Moderator Offline Posts: 1838	Re: store rgb in a array. Reply #3 - Mar 27^th, 2009, 4:33am i have to admit that i didnt unterstand what you are trying to do... but when you need exact pixels, why do you use float and not int ?
	twitter.com/CedricKiefer

PhiLho YaBB Moderator Offline Posts: 4190 Near Paris (France)	Re: store rgb in a array. Reply #4 - Mar 27^th, 2009, 4:45am Cedric is right, floats are overkill and inappropriate here. ponscard: I think that's punched cards in English (cartes perforées en français). If you need to access image colors, loadPixels is the fastest way and you can (quickly) get R, G, B components with a some bit operations.

clankill3r

Re: store rgb in a array.
Reply #5 - Mar 27^th, 2009, 6:17am

ok, I will later look at loadPixels.

for now I have a question about:
imageColors[y + x] = img.get(x, y);

I want [y + x] to be like 120 + 60 = 12060 (or 120060).
Now it will be just 180 which I understand but how can I add the x behind the y. I tried [y + "" + x] for example but that doesnt work out.

also
println(imageColors);

prints this for example, what is the 0 and why doesnt it show the value?
if I do println(imageColors[33]); then it will perfectly show the value.

[11011] 0
[11012] 0
[11013] 0
[11014] 0

Code:


PImage img;

color[] imageColors;

void setup(){
  size(50, 100);
  img = loadImage("plaatje.png");
  noLoop();
  imageColors = new color[img.width*img.height];
  for (int y = 0; y < img.height; y++) {
    for (int x = 0; x < img.width; x++){
	imageColors[y + x] = img.get(x, y);
    }
  }
  println(imageColors);
}

Cedric YaBB Moderator Offline Posts: 1838	Re: store rgb in a array. Reply #6 - Mar 27^th, 2009, 6:36am konvert it to String add it up and konvert back to int int x = 120; int y = 60; int XandY = int(Integer.toString(x)+Integer.toString(y)); println(XandY);
	twitter.com/CedricKiefer

PhiLho

Re: store rgb in a array.
Reply #7 - Mar 27^th, 2009, 6:49am

imageColors[y * 1000 + x] = img.get(x, y);

Now, I thought you made bi-dimentional arrays to avoid such computation... (and waste of memory).

As for the println, you don't tell us what is imageColor... I suppose it is a big one-dimensional array.
By default, it is initialized to 0. When you print it, it shows thousands of lines, most of them with 0. If you scroll to [33] you should see the relevant value.

clankill3r

Re: store rgb in a array.
Reply #8 - Mar 27^th, 2009, 8:13am

* 1000 is so simple but very smart

althought it doesnt work cause I get the error
ArrayIndexOutOfBounds

Can someone make a example of how to use bi-dimentional array in the code below.

Code:


void setup(){
  size(50, 100);
  img = loadImage("plaatje.png");
  noLoop();
  imageColors = new color[img.width*img.height];
  for (int y = 0; y < img.height; y++) {
    for (int x = 0; x < img.width; x++){
	imageColors[y+x] = img.get(x, y);
    }
  }
  println(imageColors);
}

PhiLho YaBB Moderator Offline Posts: 4190 Near Paris (France)	Re: store rgb in a array. Reply #9 - Mar 27^th, 2009, 8:46am `imageColors[y * img.width + x] = img.get(x, y);` You have to add the width for each past line. I don't want to look insisting, but your loop is exactly recreating the pixels[] array...

Cedric YaBB Moderator Offline Posts: 1838	Re: store rgb in a array. Reply #10 - Mar 27^th, 2009, 8:59am
	twitter.com/CedricKiefer

clankill3r

Re: store rgb in a array.
Reply #11 - Mar 27^th, 2009, 9:36am

I don't want to look insisting,

If I run it without the for loop then all values are printed 0
If I run with the for loop then the output is correct:

[11013] -3309016
[11014] -3572181
[11015] -3637975
[11016] -3638234
[11017] -3637968
[11018] -3638479
[11019] -3639510
[11020] -3705300

only the array names are still not how I want them.
It end with 11020, which is the total ammount of pixels.
The image I use now is 107x103 and I want to be able to see the positions back. What is smartest to do, a bi-dimentional array like this:

[arraynumber] { {xpos, ypos, colorvalue} }

The last pixel at right bottem wil be for example:
imageColors[11020] 107, 103, -3705300

try with and without for loop if you like
Code:

PImage img;

color[] imageColors;

void setup(){
  size(50, 100);
  img = loadImage("plaatje.png");
  noLoop();
  imageColors = new color[img.width*img.height];
  /*for (int y = 0; y < img.height; y++) {
    for (int x = 0; x < img.width; x++){
	imageColors[y * img.width + x] = img.get(x, y);
    }
  }*/
  println(imageColors);
}

Ossory

Re: store rgb in a array.
Reply #12 - Mar 27^th, 2009, 9:45am

No, PhiLho, you are absolutely correct. The _right_ way to manipulate the pixels in an image (even if you are not going to display it anywhere) is to draw that image onto a PGraphics or PImage object (or load it there, whatever), - they share alot of methods. Then manipulate the pixels using loadPixels(). pixels[] is a flat array, so if you want to access it as a two-dimensional array, you do something like this:
Code:


loadPixels();
int a,r,g,b,p;
for ( int y = 0; y < height; y++ ) {
  for (int x = 0; x < width; x++ ) {
    p = pixels[x + y*width];
    a = (p >> 24) & 0xFF;
    r = (p >> 16) & 0xFF;
    g = (p >>  8) & 0xFF;
    b = (p      ) & 0xFF;
    // Do whatever with a (for alpha) and rgb here
    // then get it back like this:
    pixels[x+y*width] = (a << 24) | (r << 16) | (g << 8) | (b);
  }
}
updatePixels();

Maybe it can be done even faster, but I don't really know how.

clankill3r Full Member Offline Posts: 210 Netherlands	Re: store rgb in a array. Reply #13 - Mar 27^th, 2009, 11:29am Ossory thx for input but it's a bit to complex for me atm, I'm kinda new to processing. now I have this: Code: color[] imageColors; can I make it color[][] and store x and y position aswell or does it have to be a normal array?

PhiLho

Re: store rgb in a array.
Reply #14 - Mar 27^th, 2009, 12:17pm

OK, let say it is for learning purpose. Which is a very valid reason, after all.
Here is what you want:
Code:

PImage img;

color[][] imageColors;

void setup(){
  size(50, 100);
  img = loadImage("D:/_PhiLhoSoft/Processing/earth.png");
  noLoop();
  imageColors = new color[img.width][img.height];
  for (int y = 0; y < img.height; y++) {
    for (int x = 0; x < img.width; x++) {
	imageColors[x][y] = img.get(x, y);
    }
  }
  println(imageColors);
  DumpColors();
} 

void DumpColors()
{
  for (int y = 0; y < img.height; y++) {
    for (int x = 0; x < img.width; x++) {
	println("x=" + x + " y=" + y + " : " + hex(imageColors[x][y]));
    }
  }
}

As you can see, Processing can't println a multi-dimensional array, you have to do it yourself.

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