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ksnctf C92 E1 Mysterious Light
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# -*- coding: utf-8 -*- | |
from PIL import Image | |
dth, lth = 50, 175 | |
marks = {'dark': 'X', 'light': '_', 'unknown': '?'} | |
def get_pix(filename): | |
with Image.open(filename) as img: | |
width, height = img.size | |
imgpix = [[] for i in range(height)] | |
for y in range(height): | |
for x in range(width): | |
imgpix[y].append(img.getpixel((x, y))) | |
return imgpix | |
def pix2txt(imgpix, unknown_patterns=[], skip=1): | |
imgtxt = [] | |
for y in range(0, len(imgpix), skip): | |
imgtxt.append('') | |
for x in range(0, len(imgpix[0]), skip): | |
pix = imgpix[y][x] | |
for uptn in unknown_patterns: | |
if uptn(pix): | |
mark = marks['unknown'] | |
break | |
else: | |
avgpix = sum(pix)/3 | |
if avgpix < dth: | |
mark = marks['dark'] | |
elif avgpix > lth: | |
mark = marks['light'] | |
else: | |
mark = marks['unknown'] | |
imgtxt[int(y/skip)] += mark | |
return imgtxt | |
def is_the_color(rgb, color): | |
l = color | |
ds = [i for i in range(3) if i != 1] | |
return (rgb[l] > lth) and (rgb[ds[0]] < dth) and (rgb[ds[1]] < dth) | |
def is_red(rgb): return is_the_color(rgb, 0) | |
def is_blue(rgb): return is_the_color(rgb, 1) | |
def is_green(rgb): return is_the_color(rgb, 2) | |
def trim(imgtxt, udlr): | |
trimtxt = [] | |
for y in range(udlr[0], len(imgtxt)-udlr[1]): | |
trimtxt.append(imgtxt[y][udlr[2]:-udlr[3]]) | |
return trimtxt | |
def main(infilename, skip=1, trim_udlr=[0, 0, 0, 0]): | |
imgpix = get_pix(infilename) | |
imgtxt = pix2txt(imgpix, [is_red, is_blue, is_green], skip) | |
imgtxt = trim(imgtxt, trim_udlr) | |
outfilename = infilename.split('.')[0] + '.txt' | |
with open(outfilename, 'w') as f: | |
for line in imgtxt: | |
f.write(line + '\n') | |
if __name__ == '__main__': | |
main('flag2.png', 8, [4, 4, 4, 4]) |
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