写真を白黒の線画風の画像にする

lineimage.py

# 写真を白黒の線画風の画像にするプログラム
# orig/*.jpg を読み込んで output/*.jpg として出力する
# http://tadaoyamaoka.hatenablog.com/entry/2017/02/19/172744
# http://gori-naru.blogspot.com/2012/11/blog-post_8647.html
import os
import shutil
import glob
import cv2
from tqdm import tqdm
import numpy as np
import math
import multiprocessing as multi

def gamma_compensation(img, gamma):
    lookUpTable = np.zeros((256, 1), dtype='uint8')
    for i in range(256):
        lookUpTable[i][0] = 255 * pow(float(i) / 255, 1.0 / gamma)
    return cv2.LUT(img, lookUpTable)

def contrast_adjustment(img, a, b):
    lookUpTable = np.zeros((256, 1), dtype='uint8')
    for i in range(256):
        lookUpTable[i][0] = 255.0 / (1+math.exp(-a*(i-b)/255))
    return cv2.LUT(img, lookUpTable)

neiborhood24 = np.array([
    [1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1],
    [1, 1, 1, 1, 1]
    ], np.uint8)

def worker(path):
    orig = cv2.imread(path)
    gray = cv2.cvtColor(orig, cv2.COLOR_RGB2GRAY)
    img_gamma = gamma_compensation(gray, 2.0)
    dilated = cv2.dilate(img_gamma, neiborhood24, iterations=1)
    diff = cv2.absdiff(dilated, img_gamma)
    contour_tmp = 255 - diff
    contour = gamma_compensation(contour_tmp, 0.2)
    contour = contrast_adjustment(contour, 8.0, 128)
    # cv2.imwrite(f'output/{os.path.basename(path)}', contour)
    cv2.imwrite(f'output/{os.path.basename(path)}', cv2.hconcat([
        orig, cv2.cvtColor(contour, cv2.COLOR_GRAY2RGB)]))

if __name__ == '__main__':
    paths = glob.glob("orig/*.jpg")
    with multi.Pool(multi.cpu_count()) as p:
        r = list(tqdm(p.imap(worker, paths), total=len(paths)))