Colouring pixels

Processing Coding Questions
21

NOW it works! It was the missing img from img.updatePixels();
I had been trying with and without.
Thank you!
(What do you think of my proposed workflow (see reply to kll).)

22

Something I was trying the other day:

PImage img;
String filename = str(month()) + str(day());

void setup() 
  {
  size(500, 500); //I want a white margin. This is currently same size as image.
  background(255);
  noLoop();
  make();
  }

void draw() 
  {
  background(0);
  image(img, (width-275)/2, (height-275)/2);
  println(frameCount);
  }
  
void make()
  {
  img = loadImage("blank.png");
  //img.width = 275;
  //img.height = 275;
  println(img.width);
  println(img.height);
  colorMode(RGB, 255, 255, 255);
  int offset = (img.width-255)/2; //to center it
 
  for (int y = offset; y < img.width-offset; y++ ) 
    {
    for (int x = offset; x < img.height-offset; x++ ) 
      {
      int loc = x + y*img.width;
      img.pixels[loc] = color(loc%img.width, (loc - (loc%img.width))/img.width, 0); //
      }
    }

  img.updatePixels();
  img.save(filename + ".jpg");
  
  println("done");  
  }

This is the “blank.png” image (275x275):
blank
And output:

image
image502×527 3.46 KB

:slight_smile:

1 Like
23

Please save this under a new file name so that you have a working version

Then work on with a new version

The proposal is homework and I wish you good luck Sir.

24

Yes, all saved as a new version with setup() and draw() as they should be.

Shall I continue with loading an image or move over to createImage() ?

The rest, as you say, is homework.

25

Thank you. That works as well. Now I need to study it!

  img.width = 255;
  img.height = 255;
26

Please tell me more.