How to save without background image

dcbvoice

Hi everyone,

Sorry if I'm repeating a question that has already been answered, but I've scoured high and low and haven't found a good solution.

I'm saving images from my processing sketch, which contains a background image called in Setup. My code in Draw uses the background image's pixels to create designs using get(). However, when I save the image, I would like for the background of the final file to just be transparent.

Is there a way to have this happen? Options I've been exploring without effect include somehow getting back into Setup once the saving is initiated or hiding the background from view (like an option you see in Photoshop).

I'd be grateful for any thoughts or help,

Thanks,

David

GoToLoop

• Rather than directly drawing to sketch's main canvas, we may choose to so in a PGraphics.
• This way, we can use its method save() rather than canvas' save() or saveFrame()!

1. https://processing.org/reference/PGraphics.html
2. https://processing.org/reference/PImage_save_.html

dcbvoice

Thanks for your help GoToLoop, but I think I've been doing this in my code, but haven't gotten results. Let me provide what I've been working with for some context:

PGraphics big;
PImage bg;
PImage fragment;
int counter = 0;
color c;

void setup() {
  bg = loadImage("black.jpg");
  big = createGraphics(2500, 2500, JAVA2D); //Create a new PGraphics
  big.beginDraw(); // Start drawing to the PGraphics object
  big.background(bg);
}

 void draw() {
   big.pushMatrix();
float a = random(457,501); //images are numbered 457-500.png
int aint = int (a); //makes fragNumber an integer 

  // rotate + scale images
  int xint;
  int yint;
  float imageScale;
  float imageRotation = random(-360, 360);
  float x = random(big.width);
  float y = random(big.height);
  xint = int(x);
  yint = int(y);
  c = bg.get(xint, yint);


  if  (c == #000000) {
  big.translate(x, y);
  big.imageMode(CENTER);
  big.rotate(radians(imageRotation));
  big.scale(random(.04, .06)); //whiteflowers
  big.image(loadImage(aint+".png"), random(0, big.width), random(0,big.height));
  }

big.popMatrix();

 }
/** 
* We save on any key 
* this could be done in void close() but safer to have it here. 
*/  
void keyPressed() {  
  big.endDraw(); // finish drawing  
  big.save("test" + ".png"); //save to file - use .tif as format for high-res  
  println("saved");
 println(frameCount); // nice with some feedback  
  println(hex(c));

}  

GoToLoop

• My tip about PGraphics was to separate your background image from your foreground drawings!
• So when you save() your PGraphics, your background image won't show up along!
• However, you mix them up again w/ big.background(bg); @ line #11!

dcbvoice

Thanks GoToLoop!