Make a mosaic art randomly with your favorite colour. (Only work on Python3)

mosaic.py

#coding:utf-8

outname = 'out.png'

import struct
import binascii
import zlib
from math import ceil
import codecs
import random
from functools import reduce

size_x = 15
size_y = 15
pixcel = 25
colour = input('base colour: ')

#allow +-3
#must be even
random_range = 100

#colour decode
colour_rgb = [int(colour[i*2:i*2+2], 16) for i in range(3)]

#変更量
def changerate(ratio):
    new_ratio = ratio + random.randint(0, random_range)-int(random_range/2)
    if new_ratio >= 255:
        return 255
    elif new_ratio <= 0:
        return 0
    else:
        return new_ratio
    
def twodigits_hex(num):
    hexized = hex(num)[2:]
    if len(hexized)==1:
        return '0'+hexized
    return hexized

def newrgb():
    return [twodigits_hex(ratio) for ratio in map(changerate, colour_rgb)]

#Random
IMAGE = reduce(lambda x,y:x+y ,[[''.join([''.join(newrgb())*pixcel for j in range(size_x)])]*pixcel for k in range(size_y)])


def crcMaker(data):
    return binascii.crc32(data)

def chunkMaker(name, chunkData):
    CRC = crcMaker(name + chunkData)
    body_len = len(chunkData)
    chunk = struct.pack('> I 4s {}s I'.format(body_len),
                        body_len, name, chunkData, CRC)
    return chunk

def hexize(data):
    return codecs.decode(data,'hex')
        

data = bytes()

#header
data += bytes((0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A))

#IHDR
width = len(IMAGE[0])//6
height = len(IMAGE)
depth = 8
colourType = 2
compress = 0
filterType = 0
adam7 = False
chunkData = struct.pack('> I I B B B B ?',
            width, height, depth, colourType, compress, filterType, adam7)
data += chunkMaker(b'IHDR', chunkData)

#IDAT
filteredImage = bytes()
filterMode = b'\x00'
inputLine = b''.join([filterMode+hexize(l) for l in IMAGE])
chunkData = zlib.compress(inputLine)
data += chunkMaker(b'IDAT', chunkData)

#IEND
data += chunkMaker(b'IEND', b'')

with open(outname, 'wb') as f:
    f.write(data)