Image Reversion using Pillow in Python.

image_reversion.py

import numpy as np
from PIL import Image
import matplotlib.pyplot as plt 

gray_img = Image.open('Lenna.png').convert("LA")#밝기와 알파값을 이용해서 Grayscale로 변환
gray_img.save("gray_lenna.png")#grayscale로 변환된 흑백 이미지를 출력
row = gray_img.size[0]
col = gray_img.size[1]
rev_img = Image.new("L", (row, col))#새 흑백이미지를 생성.
for x in range(1 , row):
    for y in range(1, col):
        rev_img.putpixel((x,y), int(255-gray_img.getpixel((x,y))[0]))
rev_img.save("reversion_lenna.png")#반전처리된 이미지 저장

y = gray_img.histogram()
y = y[0:256]
x = np.arange(len(y))
plt.figure(figsize=(8, 16))
plt.subplot(211)
plt.title("grayscale hist")
plt.bar(x, y)

y = rev_img.histogram()
x = np.arange(len(y))
plt.subplot(212)
plt.title("reversion hist")
plt.bar(x, y)
fig = plt.gcf()
plt.show()
fig.savefig("reversion_histogram.png")