Skip to content

Distorting mirror

A distorting mirror, funhouse mirror or carnival mirror is a popular attraction at carnivals and fairs. Instead of a normal plane mirror that reflects a perfect mirror image, distorting mirrors are curved mirrors, often using convex and concave sections to achieve the distorted effect. Because of their distorting properties, they are sometimes featured in fiction as a literary device, such as in Hans Christian Andersen's 1844 fairy tale The Snow Queen.

OpenCV example 

# 왜곡 거울 카메라 (workshop_distortion_camera.py)

import cv2
import numpy as np

cap = cv2.VideoCapture(0)
WIDTH = 500
HEIGHT = 300
cap.set(cv2.CAP_PROP_FRAME_WIDTH, WIDTH)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, HEIGHT)
rows, cols = HEIGHT, WIDTH
map_y, map_x = np.indices((rows, cols), dtype=np.float32)

# 거울 왜곡 효과 
map_mirrorh_x,map_mirrorh_y = map_x.copy(), map_y.copy() 
map_mirrorv_x,map_mirrorv_y = map_x.copy(), map_y.copy()    
## 좌우 대칭 거울 좌표 연산
map_mirrorh_x[: , cols//2:] = cols - map_mirrorh_x[:, cols//2:]-1
## 상하 대칭 거울 좌표 연산
map_mirrorv_y[rows//2:, :] = rows - map_mirrorv_y[rows//2:, :]-1
# 물결 효과
map_wave_x, map_wave_y = map_x.copy(), map_y.copy()
map_wave_x = map_wave_x + 15*np.sin(map_y/20)
map_wave_y = map_wave_y + 15*np.sin(map_x/20)    


# 렌즈 효과
## 렌즈 효과, 중심점 이동
map_lenz_x = 2*map_x/(cols-1)-1
map_lenz_y = 2*map_y/(rows-1)-1
## 렌즈 효과, 극좌표 변환
r, theta = cv2.cartToPolar(map_lenz_x, map_lenz_y)
r_convex = r.copy()
r_concave = r.copy()
## 볼록 렌즈 효과 매핑 좌표 연산
r_convex[r< 1] = r_convex[r<1] **2  
print(r.shape, r_convex[r<1].shape)
## 오목 렌즈 효과 매핑 좌표 연산
r_concave[r< 1] = r_concave[r<1] **0.5
## 렌즈 효과, 직교 좌표 복원
map_convex_x, map_convex_y = cv2.polarToCart(r_convex, theta)
map_concave_x, map_concave_y = cv2.polarToCart(r_concave, theta)
## 렌즈 효과, 좌상단 좌표 복원
map_convex_x = ((map_convex_x + 1)*cols-1)/2
map_convex_y = ((map_convex_y + 1)*rows-1)/2
map_concave_x = ((map_concave_x + 1)*cols-1)/2
map_concave_y = ((map_concave_y + 1)*rows-1)/2

while True:
    ret, frame = cap.read()
    frame = frame[:HEIGHT, :WIDTH]
    # 준비한 매핑 좌표로 영상 효과 적용
    mirrorh=cv2.remap(frame,map_mirrorh_x,map_mirrorh_y,cv2.INTER_LINEAR)
    mirrorv=cv2.remap(frame,map_mirrorv_x,map_mirrorv_y,cv2.INTER_LINEAR)
    wave = cv2.remap(frame,map_wave_x,map_wave_y,cv2.INTER_LINEAR, \
                    None, cv2.BORDER_REPLICATE)
    convex = cv2.remap(frame,map_convex_x,map_convex_y,cv2.INTER_LINEAR)
    concave = cv2.remap(frame,map_concave_x,map_concave_y,cv2.INTER_LINEAR)
    # 영상 합치기
    r1 = np.hstack(( frame, mirrorh, mirrorv))
    r2 = np.hstack(( wave, convex, concave))
    merged = np.vstack((r1, r2))

    cv2.imshow('distorted', merged)
    if cv2.waitKey(1) & 0xFF== 27:
        break
cap.release
cv2.destroyAllWindows()

See also

Favorite site