It is basic math with angles in triangle.
if you have two points (x1,y1), (x2, y2) then you can calculate dx = x2-x1, dy = y2-y1 and then you can calculate tangens_alpha = dy/dx and alpha = arcus_tangens(tangens_alpha) and you have angle which you hava to use to calculate rotation - 90-alpha
In Python it will be as below. I took points from your image.
Because image have (0,0) in top left corner, not in bottom left corner like in math so I use dy = -(y2 - y1) to flip it
import math
x1 = 295
y1 = 605
x2 = 330
y2 = 100
dx = x2 - x1
dy = -(y2 - y1)
alpha = math.degrees(math.atan2(dy, dx))
rotation = 90-alpha
print(alpha, rotation)
And now you can use PIL/pillow or cv2+imutils to rotate it
import math
import cv2
import imutils
x1 = 295
y1 = 605
x2 = 330
y2 = 100
dx = x2 - x1
dy = -(y2 - y1)
alpha = math.degrees(math.atan2(dy, dx))
rotation = 90-alpha
print(alpha, rotation)
img = cv2.imread('image.jpg')
img_2 = imutils.rotate(img, rotation)
cv2.imwrite('rotate.jpg', img_2)
img_3 = imutils.rotate_bound(img, -rotation)
cv2.imwrite('rotate_bound.jpg', img_3)
cv2.imshow('rotate', img_2)
cv2.imshow('rotate_bound', img_3)
cv2.waitKey(0)
rotate.jpg
rotate_bound.jpg
dxanddyand you can use it to calculate (as I remeber)tan(alpha) = dy/dxand then you can calculatealpha = atan(dy/dx). You can calculatealphawith standard modulemath. And when you havealphathen you can use PIL/pillow or cv2 to rotate it.