Remember that the pixel information is stored inside of an array. Therefore, there is a similar coordinate system that maps the screen or an image. The top left will be ```(0,0)```. 
The cv2.line() method requires the image object, two coordinate values, color and pixel thickness. 
```python
img = cv2.line(frame, (0,0), (width, height), (255, 0,0), 10)
cv2.imshow('frame', img)
```

To draw multiple lines, we need to draw the new line on the modified img object. 
```python
img = cv2.line(frame, (0,0), (width, height), (255, 0,0), 10)
img = cv2.line(img, (0,height), (width, 0), (0, 255,0), 5)
cv2.imshow('frame', img)
```



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This is a very important feature to understand because it will be necessary to create circles, squares, etc. when labeling and identifying eyes. 

Shape Creation 

Line Method

This method requires an img object, top left and bottom right coordinate, color and line thickness. 
```python
img = cv2.rectangle(frame, (100,100), (200,200), (128, 128, 128), 5)
```
If the thickness is set to be -1 instead of a positive integer, then it would fill the rectangle in completely instead of just having an outline. 

Rectangle Method

This method requires an img object, center coordinate and radius, color and line thickness.
```python
img = cv2.circle(frame, (100, 100), 60, (0,0,255), -1)
```
This would fill in the circle since the thickness is specified as -1. The circle method will construct a circle at the coordinate value passed that goes ```r``` units away in all directions.

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