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Index › Programming Questions & Help › OpenGL and 3D Libraries › img scale artifacts

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img scale artifacts (Read 1037 times)

klankschap YaBB Newbies Offline Posts: 15	img scale artifacts Oct 23^rd, 2007, 10:30pm if you draw 80x80 pixels into an img and then scale that img by a factor 2, you get a blurred variant compared to drawing rect of 2x2 onto the screen... why? F

extrapixel Full Member Offline Posts: 210 Switzerland	Re: img scale artifacts Reply #1 - Oct 24^th, 2007, 3:58pm hi, not sure if i understand... but isn't it just because we're working with pixels here, not vectors? Or else, post a code snippet demonstrating the problem you describe.
	http://www.extrapixel.ch

klankschap

Re: img scale artifacts
Reply #2 - Oct 24^th, 2007, 4:06pm

extrapixel wrote on Oct 24^th, 2007, 3:58pm:

hi,

not sure if i understand... but isn't it just because we're working with pixels here, not vectors
Or else, post a code snippet demonstrating the problem you describe.

Yes i fill an PImage (80x80) with pixels and then use it as a texture which is then scaled 2.0

I expected to see rectangles, but i guess i need to set some special rendering bits somewhere...

extrapixel

Re: img scale artifacts
Reply #3 - Oct 24^th, 2007, 4:27pm

ah, now I understand. Not sure about this across renderers... but this works as you expected at least in JAVA2D and smooth() turned off.

Click to turn smooth on/off:

Quote:

PImage img;
boolean smoothOn;

void setup() {
size(200,200);
img = createImage(80,80, RGB);
for(int i=0; i < img.pixels.length; i++) {
img.pixels[i] = color(random(255), random(255), random(255));
}
noSmooth();
smoothOn = false;
}

void draw() {
background(0);
scale(20.0);
image(img,0,0);
}

void mousePressed() {
if (smoothOn) {
noSmooth();
smoothOn = false;
println("smooth off");
}
else {
smooth();
smoothOn = true;
println("smooth on");
}
}

http://www.extrapixel.ch

fry YaBB Moderator Offline Posts: 2623 mass, usa	Re: img scale artifacts Reply #4 - Oct 24^th, 2007, 5:15pm there is currently no way to make all the renderers do nearest neighbor filtering. sorry.

decinoge

Re: img scale artifacts
Reply #5 - Oct 25^th, 2007, 1:30am

Well, i've been having this same problem.
However i ask, isn't there a way to implement nearest neighbor?
well, i'm not exactly telling it to be done on a full aplication render, but at least on the PImage or PGraphics level.

I know next to nothing in graphics processing, but still this was suposed to be the easyest way to scale.

Maybe with OpenGL help or using OpenGL surfaces?
(that would also make it possible to implement resizeble application windows).

Once a teacher of mine was able to do a resizeble window, with nearest neighbor scaling using jogl. That particular piece of code was just a few lined after and before the render, with just the problem that the colors were all messed up (due to ARGB of OpenGL and not RPGA) and the image was also inverted. however i've lost that code since i had a problem with a hard-drive -_-!!. I'll try to ask him for the same effect.

klankschap

Re: img scale artifacts
Reply #6 - Oct 25^th, 2007, 12:20pm

[quote author=extrapixel]
Click to turn smooth on/off:
[/quote]

This works.
However is seems impossible to update the img in the draw() loop.
e.g. this gives a single static noise image, instead of a dyunamic one...

Code:


PImage img[] = { 
  createImage(80,80, RGB),
  createImage(80,80, RGB),
  createImage(80,80, RGB),
  createImage(80,80, RGB)
  };
  boolean smoothOn;

void setup() {
  size(800,800);
  noSmooth();
  smoothOn = false;

}


void draw() {
  background(0);
  for ( int k = 0; k < img.length; k++ ) {
    loadPixels();
    for(int i=0; i < img[k].pixels.length; i++) {
	img[k].pixels[i] = color(random(255), random(255), random(255));  
    }
    updatePixels();
  }

  scale(2.0);
  int k = 0;
  for ( int x = 0; x < 2; x++ ) {
    for ( int y = 0; y < 2; y++ ) {
	image(img[k++],x*80,y*80);
    }  
  }
}

void mousePressed() {
  if (smoothOn) {
    noSmooth();
    smoothOn = false;
    println("smooth off");
  }  
  else {
    smooth();
    smoothOn = true;
    println("smooth on");
  }  
}

JohnG Ex Member	Re: img scale artifacts Reply #7 - Oct 25^th, 2007, 1:07pm Try changeing your loadPixels() and updatePixels() to img[k].loadPixel() and img[k].updatePixels();

klankschap YaBB Newbies Offline Posts: 15	Re: img scale artifacts Reply #8 - Oct 25^th, 2007, 1:27pm Quote: Try changeing your loadPixels() and updatePixels() to img[k].loadPixel() and img[k].updatePixels(); YES! thanks

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