Introduction

Recently, I built a small Python project that allows users to generate images by drawing shapes like rectangles and squares directly onto a canvas.

The idea was simple:
Instead of using a graphics library with buttons and UI, I wanted to understand how images actually work at a lower level, pixel by pixel.

This project helped me better understand:

• Object-Oriented Programming (OOP)
• NumPy array manipulation

Images as 3D Data Structures

Instead of thinking in terms of “graphics”, I worked with a 3D array structured as:

self.data = np.zeros((self.height, self.width, 3), dtype=np.uint8)

#This creates a 3D NumPy array:
(height, width, 3)

Command Line inputs

Project Structure

• main.py handles user input and calls the drawing logic.
• canvas.py creates the image data and saves it.
• shapes.py contains Rectangle and Square classes with a draw() method.

How drawing works

• The canvas is a NumPy array of pixels.
• Each shape changes a rectangular slice of that array.
• Saving converts the array into a PNG using PIL.

canvas.data[row:row+height, col:col+width] = (r, g, b)