python challenge 7
进入页面，得到线索：
it's in the air. look at the letters.
看字母，O2氧气的英文是oxygen，进入页面
import urllib.request
file = open('oxygen.png', 'wb')
im_data = urllib.request.urlopen('http://www.pythonchallenge.com/pc/def/oxygen.png')
file.write(im_data.read())
file.close() 得到图片 “oxygen.png”
很显然，图片中间的灰色区域藏了下一关的线索，百度python图像处理，知道可以使用PIL库
from PIL import Image
image = Image.open('oxygen.png')使用size获得图片的尺寸>>> image.size(629, 95)
>>> image.mode
'RGBA'然后就需要检查图像的像素的信息了，对于‘RGB’颜色而言，有三个参数分别代表三种颜色各自的值使用getpixel（xy）方法得到坐标（x，y）处的像素信息，目的是获得中间条形区域范围
首先检查纵坐标范围，再检查横坐标范围
for i in range(95):
print(image.getpixel((0,i)),i)
(79, 92, 23, 255) 0
(60, 72, 8, 255) 1
(68, 79, 21, 255) 2
(104, 111, 59, 255) 3
(39, 32, 0, 255) 4
(57, 44, 2, 255) 5
(67, 54, 12, 255) 6
(141, 130, 85, 255) 7
(107, 104, 51, 255) 8
(119, 120, 63, 255) 9
(125, 125, 71, 255) 10
(118, 118, 64, 255) 11
(118, 119, 62, 255) 12
(137, 136, 82, 255) 13
(135, 133, 82, 255) 14
(164, 153, 107, 255) 15
(206, 181, 140, 255) 16
(213, 181, 140, 255) 17
(206, 173, 132, 255) 18
(214, 179, 139, 255) 19
(221, 187, 149, 255) 20
(218, 184, 146, 255) 21
(219, 185, 148, 255) 22
(222, 188, 150, 255) 23
(203, 168, 128, 255) 24
(199, 162, 120, 255) 25
(194, 155, 112, 255) 26
(180, 142, 97, 255) 27
(189, 151, 106, 255) 28
(192, 155, 110, 255) 29
(179, 143, 93, 255) 30
(161, 139, 82, 255) 31
(124, 124, 60, 255) 32
(110, 125, 58, 255) 33
(116, 132, 67, 255) 34
(113, 132, 66, 255) 35
(106, 127, 62, 255) 36
(111, 132, 65, 255) 37
(112, 129, 61, 255) 38
(121, 136, 67, 255) 39
(129, 145, 74, 255) 40
(121, 137, 66, 255) 41
(124, 135, 67, 255) 42
(115, 115, 115, 255) 43
(115, 115, 115, 255) 44
(115, 115, 115, 255) 45
(115, 115, 115, 255) 46
(115, 115, 115, 255) 47
(115, 115, 115, 255) 48
(115, 115, 115, 255) 49
(115, 115, 115, 255) 50
(115, 115, 115, 255) 51
(98, 127, 47, 255) 52
(105, 134, 54, 255) 53
(96, 123, 44, 255) 54
(104, 131, 52, 255) 55
(102, 129, 50, 255) 56
(111, 135, 57, 255) 57
(111, 134, 54, 255) 58
(114, 135, 56, 255) 59
(109, 132, 50, 255) 60
(98, 126, 42, 255) 61
(89, 123, 36, 255) 62
(79, 115, 27, 255) 63
(70, 108, 23, 255) 64
(96, 131, 49, 255) 65
(110, 138, 61, 255) 66
(97, 125, 50, 255) 67
(92, 122, 48, 255) 68
(93, 125, 52, 255) 69
(99, 129, 57, 255) 70
(104, 131, 60, 255) 71
(105, 131, 60, 255) 72
(118, 141, 69, 255) 73
(109, 136, 59, 255) 74
(101, 128, 51, 255) 75
(106, 132, 58, 255) 76
(111, 137, 63, 255) 77
(99, 126, 45, 255) 78
(95, 123, 39, 255) 79
(92, 120, 36, 255) 80
(98, 125, 44, 255) 81
(94, 123, 41, 255) 82
(89, 118, 38, 255) 83
(89, 117, 40, 255) 84
(90, 118, 41, 255) 85
(97, 128, 48, 255) 86
(88, 120, 37, 255) 87
(89, 121, 36, 255) 88
(81, 114, 27, 255) 89
(89, 121, 36, 255) 90
(90, 124, 37, 255) 91
(78, 113, 21, 255) 92
(80, 115, 25, 255) 93
(93, 127, 43, 255) 94可以知道灰色区域的纵坐标范围为43-51，再确定43行来检测横坐标范围：
for i in range(629):
print(image.getpixel((i,43)),i)最后面的几行是这样的：
(49, 49, 49, 255) 585
(50, 50, 50, 255) 586
(50, 50, 50, 255) 587
(50, 50, 50, 255) 588
(50, 50, 50, 255) 589
(50, 50, 50, 255) 590
(50, 50, 50, 255) 591
(50, 50, 50, 255) 592
(49, 49, 49, 255) 593
(49, 49, 49, 255) 594
(49, 49, 49, 255) 595
(49, 49, 49, 255) 596
(49, 49, 49, 255) 597
(49, 49, 49, 255) 598
(49, 49, 49, 255) 599
(93, 93, 93, 255) 600
(93, 93, 93, 255) 601
(93, 93, 93, 255) 602
(93, 93, 93, 255) 603
(93, 93, 93, 255) 604
(93, 93, 93, 255) 605
(93, 93, 93, 255) 606
(93, 93, 93, 255) 607
(65, 47, 1, 255) 608
(117, 99, 49, 255) 609
(132, 116, 65, 255) 610
(110, 93, 47, 255) 611
(129, 116, 71, 255) 612
(112, 105, 53, 255) 613
(113, 106, 54, 255) 614
(161, 145, 96, 255) 615
(148, 126, 79, 255) 616
(147, 118, 74, 255) 617
(166, 137, 97, 255) 618
(143, 118, 88, 255) 619
(85, 61, 33, 255) 620
(83, 59, 25, 255) 621
(97, 71, 34, 255) 622
(107, 79, 42, 255) 623
(106, 78, 41, 255) 624
(109, 84, 44, 255) 625
(98, 73, 32, 255) 626
(103, 74, 32, 255) 627
(94, 62, 21, 255) 628
message = []
for i in range(0,608,7):
message.append(list(image.getpixel((i,43)))[0])得到：
print(message)
[115, 109, 97, 114, 116, 32, 103, 117, 121, 44, 32, 121, 111, 117, 32, 109, 97, 100, 101, 32, 105, 116, 46, 32, 116, 104, 101, 32, 110, 101, 120, 116, 32, 108, 101, 118, 101, 108, 32, 105, 115, 32, 91, 49, 48, 53, 44, 32, 49, 49, 48, 44, 32, 49, 49, 54, 44, 32, 49, 48, 49, 44, 32, 49, 48, 51, 44, 32, 49, 49, 52, 44, 32, 49, 48, 53, 44, 32, 49, 49, 54, 44, 32, 49, 50, 49, 93]怀疑是 ASCII码，翻译一下：
answer = ''
for i in message:
answer += chr(i)
print(answer)
smart guy, you made it. the next level is [105, 110, 116, 101, 103, 114, 105, 116, 121]
又得到了一个数组，再翻译一下：
m = [105, 110, 116, 101, 103, 114, 105, 116, 121]
n = ''
for i in m:
n += chr(i)
print(n)
integrity得到答案 integrity
百度翻译：n. 完整;正直，诚实; [计算机]保存;健全
完整代码：
import urllib.request
from PIL import Image
file = open('oxygen.png', 'wb')
im_data = urllib.request.urlopen('http://www.pythonchallenge.com/pc/def/oxygen.png')
file.write(im_data.read())
file.close()
image = Image.open('oxygen.png')
message = []
for i in range(0,608,7):
message.append(list(image.getpixel((i,43)))[0])
answer = ''
for i in message:
answer += chr(i)
print(answer)