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IceCTF 2016 – Pretty Pixels

Problem

Don't get me wrong, I love pretty colors as much as the next guy... but what does it mean?

Solution

If we preview the image, it is just pure multicolored noise.

image = Import["https://play.icec.tf/problem-static/pretty_pixels_604e889db44de75ea4541a23e344b80eb315f0faf4136abc6d40e1fff8802c9f.png"]

pretty pixels

We want the values for each pixel. We could use ImageData[image,"byte"], or we can specify "Data" when downloading the image to get the byte data of each pixel.

imageData =
  Import[
   "https://play.icec.tf/problem-static/pretty_pixels_604e889db44de75ea4541a23e344b80eb315f0faf4136abc6d40e1fff8802c9f.png",
   "Data"];

Lets try to interpret the first 100 pixels (300 RGB values) of the image as ASCII bytes.

FromCharacterCode[Flatten[imageData][[;; 300]]]
�PNG



IHDR&	s(bKGDÿÿÿ ½§�	pHYs��tIMEà"Wÿ0fEiTXtCommentCREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 80
f_-w IDATxÚ̽y�åuy5~ºûÞ¾{ßÞféÙ��ÑP,3FË� Á*�X�I¦"�(¸U¢�|Q4j¢&Æ1hX¢��BXY�mgÆÙ��^nßýö½}û/�ïùüÎ}æùÜnß¼oÅ®���¾Ë/ûù~�ó�

That looks like the PNG header. Let's interpret pixel of the image as bytes and convert it into a string of binary data. Then use ImportString[] to import the data as if it were a file of binary data.

ImportString@FromCharacterCode@Flatten@imageData

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