Codeforces' Hidden Feature — Multiple Profile Images!

Revision en3, by HYPERHYPERHYPERCUBELOVER, 2016-02-14 19:43:36

Today, I found out Codeforces' Hidden Feature. Look at the following. My large profile image and small profile image are different!

I can't believe this!

Look here and here. Still not convinced? Upload this and check how your profile images are changed.

Why this works?

I uploaded this to change my profile image. The result was amazing. Large profile image is almost black, but small profile image is white. It seems that Codeforces' image scaling algorithm is Nearest-neighbor interpolation. Nearest-neighbor interpolation uses data of a few pixels. If we therefore, 이 픽셀들에 두 개의 이미지를 나눠서 저장한 뒤 업로드하면 두 이미지를 다르게 설정할 수 있다.

So, how can I make them differ?

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en13 English HYPERHYPERHYPERCUBELOVER 2016-02-14 23:13:23 0 (published)
en12 English HYPERHYPERHYPERCUBELOVER 2016-02-14 23:12:55 5 Tiny change: 's is just guessing!)\n\nNear' -> 's is just a guess!)\n\nNear' (saved to drafts)
en11 English HYPERHYPERHYPERCUBELOVER 2016-02-14 21:12:40 0 (published)
en10 English HYPERHYPERHYPERCUBELOVER 2016-02-14 21:09:34 0 Tiny change: 'per sizes.\n\nNeares' -> 'per sizes. (This is just guessing!)\n\nNeares'
en9 English HYPERHYPERHYPERCUBELOVER 2016-02-14 21:06:46 25 Tiny change: 'per sizes.\n\nNeares' -> 'per sizes. (This is just guessing!)\n\nNeares'
en8 English HYPERHYPERHYPERCUBELOVER 2016-02-14 21:00:47 30 Tiny change: 'ile image are different' -> 'ile image looks different'
en7 English HYPERHYPERHYPERCUBELOVER 2016-02-14 20:57:37 205 Tiny change: 'ile image are different' -> 'ile image looks different'
en6 English HYPERHYPERHYPERCUBELOVER 2016-02-14 20:51:28 8 Tiny change: 'ile image are different' -> 'ile image looks different'
en5 English HYPERHYPERHYPERCUBELOVER 2016-02-14 20:50:41 819
en4 English HYPERHYPERHYPERCUBELOVER 2016-02-14 20:04:33 256
en3 English HYPERHYPERHYPERCUBELOVER 2016-02-14 19:43:36 722
en2 English HYPERHYPERHYPERCUBELOVER 2016-02-14 19:23:50 50 Tiny change: 'different!\n\nYou can't ' -
en1 English HYPERHYPERHYPERCUBELOVER 2016-02-14 18:53:55 486 Initial revision (saved to drafts)