This is a very simple python program that uses open cv to generate images using the halftone technique.

(If you like this repo, you may also like this one)

Put the source image in the same directory as halftone.py and call it like so:

python3 halftone.py woman.jpg

You can also learn about the optional arguments, doing so: python3 halftone.py -h

import halftone

halftone.halftone("woman.jpg")

Learn more about the methods' signature and behaviour with python3 -m pydoc halftone

The generated image is composed of squares with dots in them. This optional argument specifies how big each of these squares can be.

As you can see from the generated images below, when all other parameters are constant, as you increase size the image becomes more smooth (because each individual dot gets smoother). (below each output image is its corresponding size and dimensions)

If you set side = 1, you won't get very good results (because each square will effectively be just one pixel).

If you set side = 2 each square will be 2 pixels wide and although you probably won't get a very clear image, you get a cool looking texture if you zoom in enough.

Values of side that are too large create big images that may take a while to generate.

The default side value is 20 pixels because from my experience playing with this variable, 20 gives you a nice equilibrium between image size and image smoothness.

The generated image is created from an input image which is scanned left to right, top to bottom. Instead of scanning the image pixel by pixel, the image is scanned in blocks, i.e. squares that are jump pixels wide. Each of these blocks will be converted into a dot in the output image.

As you can see from the images below, when all other parameters are constant, as you increase jump the image becomes less clear because bigger blocks are being condensed to the same space (size is constant). (below each output image is its corresponding jump and dimensions)

The higher the value of jump, the lower the number of dots in the output image will be (in fact, if you set this value high enough, the output picture will be a single dot).

If you set jump = 1, you're forcing the program to create a dot for each pixel in the original image (!) which will take forever and generate huge output images.

bg_color sets the background color of the output image.

fg_color sets the foreground color of the output image, i.e. the color of the dots.

Below are some examples of what you can achieve playing with these values.

I recommend using a light color for the background and a dark color for the foreground; otherwise the image will look... weird. That's why the default color for bg_color is white, and default color for fg_color is black.

If you are calling the program using the command line interface, you have to specify the color like so: python3 halftone.py woman.jpg -fg '(255,0,0)' (using '' to delimit the rgb value).

If you are calling the program from another module, this optional argument is a tuple, so you specify it like so: halftone.halftone("woman.jpg", fg_color = (255,0,0)).

Each dot is drawn in a side pixels wide square. If alpha = 1, each dot's radius will never be greater than side (i.e. at most, the dots are inscribed in their squares). When the dots' size is limited like this, the output image can look a bit faded, as you can see from the images below.

(below each output image is its corresponding alpha; the dimensions were omitted because changing alpha doesn't affect the image size)

If you set alpha = 0, the output image will have no dots (their radius will all be 0).

The photo I've been using is called Woman in White Robe Smiling and you can see the original version here. Check out this photo's original photographer here.

This program is licensed under the MIT License - see the LICENSE file for details.