import cv2
import numpy as np
import matplotlib.pyplot as plt
# Affine
def affine(img, a, b, c, d, tx, ty):
H, W, C = img.shape
# temporary image
_img = np.zeros((H + 2, W + 2, C), dtype=np.float32)
_img[1:H + 1, 1:W + 1] = img
# get new image shape
H_new = np.round(H * d).astype(int)
W_new = np.round(W * a).astype(int)
out = np.zeros((H_new + 1, W_new + 1, C), dtype=np.float32)
# get position of new image
x_new = np.tile(np.arange(W_new), (H_new, 1))
y_new = np.arange(H_new).repeat(W_new).reshape(H_new, -1)
# get position of original image by affine
adbc = a * d - b * c
x = np.round((d * x_new - b * y_new) / adbc).astype(int) - tx + 1
y = np.round((-c * x_new + a * y_new) / adbc).astype(int) - ty + 1
x = np.minimum(np.maximum(x, 0), W + 1).astype(int)
y = np.minimum(np.maximum(y, 0), H + 1).astype(int)
# assgin pixcel to new image
out[y_new, x_new] = _img[y, x]
out = out[:H_new, :W_new]
out = out.astype(np.uint8)
return out
# Read image
img = cv2.imread("../imori.jpg").astype(np.float32)
# Affine
out = affine(img, a=1, b=0, c=0, d=1, tx=30, ty=-30)
# Save result
cv2.imshow("result", out)
cv2.waitKey(0)
cv2.imwrite("out.jpg", out)
