OpenCV (6) - 임계점 처리하기

cv2.threshold(image,thresh,max_value,type) : 임계값을 기준으로 흑/백으로 분류하는 함수 (이진화 수행)

image : 처리할 Gray Scale 이미지
thresh : 임계 값 (전체 픽셀 적용)
max_value : 임계 값을 넘었을 때 적용할 값
type : 임계점을 처리하는 방식
- THRESH_BINARY : 임계 값보다 크면 max_value, 작으면 0
- THRESH_BINARY_INV : 임계 값보다 작으면 max_value, 크면 0
- THRESH_TRUNC : 임계 값보다 크면 임계 값, 작으면 그대로
- THRESH_TOZERO : 임계 값보다 크면 그대로, 작으면 0
- THRESH_TOZERO_INV : 임계 값보다 크면 0, 작으면 그대로

 

import cv2
import matplotlib.pyplot as plt

image = cv2.imread('gray_image.jpg', cv2.IMREAD_GRAYSCALE)

images = []
ret, thres1 = cv2.threshold(image, 127, 255, cv2.THRESH_BINARY) # ret은 return의 성격, 잘 읽어왔다면 thresh 값 반환
ret, thres2 = cv2.threshold(image, 127, 255, cv2.THRESH_BINARY_INV)
ret, thres3 = cv2.threshold(image, 127, 255, cv2.THRESH_TRUNC)
ret, thres4 = cv2.threshold(image, 127, 255, cv2.THRESH_TOZERO)
ret, thres5 = cv2.threshold(image, 127, 255, cv2.THRESH_TOZERO_INV)
images.append(thres1)
images.append(thres2)
images.append(thres3)
images.append(thres4)
images.append(thres5)

for i in images:
    plt.imshow(cv2.cvtColor(i, cv2.COLOR_GRAY2RGB))
    plt.show()