Converting pixel in binary values... clockwise!

Programming Questions

pelletta

Converting pixel in binary values... clockwise!

in Programming Questions • 2 years ago

Hi all, I am new to processing an I need help...
First of all I have to say that I am italian and I am sorry for my poor english so I hope you will understand my question.

I should convert the pixels of a grayscale image (I use only white and black, not intermediate colours) to binary numbers, 0 if the pixel is white and 1 if it is black and I should put these values in some array. Suppose that the image is divided into rows and columns of pixels, the thing is pretty easy because with the function pixel() I can make an array of values for each column. Instead I have to do a particular thing: assuming to have a round clock with an image in its own background, while the seconds hand moves, it takes the pixels in the image below and make up the array...
I have written this little sketch:

PImage img;
float degree = 0; // holds the angle for rotation
int counter = 0; // holds the steps for rotations

void setup()
{
size(220, 220);
img = loadImage("penguin.gif"); // loading the image
imageMode(CENTER);
smooth();
}

void draw()
{
background(255);
translate(width / 2, height / 2);
image(img,0,0);
noFill();
ellipse(0, 0, 200, 200);// transparent circle
if(counter < 100)// I make 100 steps of 3.6 degree
{
    degree += radians(3.6);
    rotate(degree);
    counter++;
}
rect(0,0,1,88); // clock hand that rotates every step
// and now???

How I can assign the pixel in the background image to the rectangle? Is this the right way to solve my problem or there are better methods?

Thanks for your attention,
Roberto

Replies(2)

amnon.owed

Re: Converting pixel in binary values... clockwise!

2 years ago

All right, assuming there is a reason you want the pixels exactly in the order of the clock (which is a little more work than just from the pixel array either all of them or just the ones at a certain distance from a point).

But if you want clock order, then I would not use rotate, but instead use sin-cos to generate an x and y position for every point on the circle. The advantage is that this 'goes around the clock' so to speak plus you will be able to use the x-y to get() the pixel color at all these x,y positions. Based on the color you can fill the array of ints with 0's and 1's.

pelletta

Re: Converting pixel in binary values... clockwise!

2 years ago

Thanks a lot, very usefull idea!
I'll try...

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