In OpenCV, the cv2.rectangle() function is used to draw a rectangle on an image. The function requires five parameters:

• the image to be modified;
• the top-left corner coordinates of the rectangle (specified as a tuple of x and y coordinates);
• the bottom-right corner coordinates of the rectangle (specified as a tuple of x and y coordinates);
• the color of the rectangle (specified as a tuple of Red, Green, Blue values);
• the thickness of the rectangle, which is optional and can be set to a negative value to fill the rectangle.

Congratulations on completing your Python project on handling images! Your hard work and dedication to learning and mastering the tools and techniques of image processing is truly impressive. I hope you enjoyed the journey and look forward to seeing the amazing things you will create with your newfound skills. Keep up the good work!