Image rotation iterator

# Image rotation iterator

# Original video & blog post by jk-keller
# https://www.youtube.com/watch?v=1UuQCDgiqVg
# https://jk-keller.com/o__o/rotational_growth/

# Python code by yclee126

import cv2
import numpy as np
import time


### User Settings ###

image_filename = 'image.png'

angle_increment = 10                # degrees, (+): counter clockwise, (-): clockwise
rotation_count = 100
interpolation = cv2.INTER_CUBIC     # see interpolation parameter table below

display_frames = 1                  # True(1) or False(0) -- (keys) q: quit, p: pause, s: skip
frame_delay = 1                     # milliseconds, 0: frame-by-frame, 1: fastest

padding_color = (255, 255, 255)     # BGR order
extra_padding = 10  # pixels

# interpolation params
#
# INTER_NEAREST  (nearest neighbor interpolation)
# INTER_LINEAR   (bilinear interpolation)
# INTER_CUBIC    (bicubic interpolation)
# INTER_AREA     (resampling using pixel area relation)
# INTER_LANCZOS4 (Lanczos interpolation over 8x8 neighborhood)


### Image processing codes ###

img = cv2.imread(image_filename)

h, w, *c = img.shape
if len(c) == 0: # grayscale image
    img = cv2.cvtColor(img, cv2.COLOR_GRAY2BGR)

# make canvas that can fit the diagonal line of the image + extra padding
final_size = int((h*h + w*w)**(1/2) + extra_padding*2)
canvas = np.zeros((final_size, final_size, 3), dtype='uint8')
canvas[:, :] = padding_color

# paste image in the center
x_offset = int((final_size - w) / 2)
y_offset = int((final_size - h) / 2)
canvas[y_offset:y_offset+h, x_offset:x_offset+w] = img

# calc infos
iterations = abs(round(360 / angle_increment * rotation_count))

print(f'Increment: {angle_increment} deg, Rotations: {rotation_count}, Iterations: {iterations}')
print_progress = lambda i: print(f'Progress: {i/iterations*100:.2f}% (r:{int(abs(i*angle_increment) / 360)}, i:{i})', end='\r')

# main rotation loop
rotated = canvas
prev_print_time = time.time()
for i in range(iterations):

    # print progress
    if time.time() - prev_print_time > 0.1 or display_frames: # prevent print() slowing down calculation
        print_progress(i)
        prev_print_time = time.time()

    # rotate canvas
    matrix = cv2.getRotationMatrix2D((final_size/2, final_size/2), angle_increment, 1.0)
    rotated = cv2.warpAffine(
        rotated,
        matrix,
        (final_size, final_size),
        None,
        interpolation,
        cv2.BORDER_CONSTANT,
        padding_color)

    if display_frames:
        # display frame
        cv2.imshow('win', rotated)
        key = cv2.waitKey(frame_delay)

        # process pause input first
        if key == ord('p'):
            key = cv2.waitKey(0)

        # process other key inputs
        if key == ord('q'):
            exit()
        elif key == ord('s'):
            display_frames = False
            cv2.destroyAllWindows()

# display final frame
print_progress(iterations)
cv2.imshow('win', rotated)
cv2.waitKey(0)

# save image
cv2.imwrite('output.png', rotated)