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        Rapidshare's new captcha can be resolved using pattern search. First, we adjust the grid on Y axis and then on X axis like in the old method.


        After doing a median filtering, the histogram looks like this:


        Highest frequencies are the grid, so they are removed.


        We do a histogram adjustment to remove the grid.

        To make the letters uniform and to remove isolated pixels or pixel groups we do a Haar Transform.


        Then we do another histogram adjustment.


        And we isolate letters and re-scale them to fit in an 16x16 matrix each.

0000000111111100
0000000111111111
0000000000011111
0110000000001111
1110000000001111
1110000000001111
1111100000001111
1111110000000100
0111111111111111
0111111111111111
0000000000001110
0000000000011100
0000000000010000
0000000000010000
0111111101110000
0111111111000000
 0000001111111100
0000001111111110
0010000000011110
0010000000011110
1100000000001111
1100000000001111
1110000000000111
1100000000000111
1100000000000111
1110000000000111
1110000000001110
1110000000001110
1111000000000000
1111110000000000
0111111100001100
0011111111111100
 0011111111111100
0010011111111111
1110000000111111
1110000000001111
1111000000001111
1110000000001111
1111000000001111
1111100000001111
1111111111111111
0111111111111110
0011111111111111
0000000000001110
0000000000000000
0111000000000000
0111100111110000
0111111111110000
 0000000011111000
0001111111111100
0011101000001100
0111000000000000
1100000000000000
1100000000000000
1100000000000000
1100000000000000
1100000000000000
1110000000000000
1111000000000000
1111100000000000
0111100000000000
0011111000000011
0011111111111111
0001111111111111
9O9C

        Doing a pattern search will return the letters that have the biggest number of common pixels with captcha letters.

        Test results for current version of captcha.dll using 100 downloaded captchas:
!15WW.gif -> 15WW
F!1ALS.gif -> YALS
!27OW.gif -> 27OW
F!2JSG.gif -> 2J5G
!2NM8.gif -> 2NM8
!2XQO.gif -> 2XQO
!33SG.gif -> 33SG
!3B74.gif -> 3B74
F!3GI8.gif -> 8Q87
!3PWO.gif -> 3PWO
!4N3K.gif -> 4N3K
!5HGW.gif -> 5HGW
!5MSO.gif -> 5MSO
F!675C.gif -> 675O
!6A8G.gif -> 6A8G
!6BU8.gif -> 6BU8
!6X74.gif -> 6X74
!77XS.gif -> 77XS
!78KO.gif -> 78KO
!7QY8.gif -> 7QY8
!7RKG.gif -> 7RKG
!8NAO.gif -> 8NAO
!92UO.gif -> 92UO
!98J4.gif -> 98J4
!9J9S.gif -> 9J9S
!9O9C.gif -> 9O9C
!9T9S.gif -> 9T9S
!A87K.gif -> A87K
!AFDC.gif -> AFDC
!AOXC.gif -> AOXC
F!ARCG.gif -> 4RCC
!C2MO.gif -> C2MO
!DIUO.gif -> DIUO
!DVBK.gif -> DVBK
F!EINK.gif -> NN1K
!ELQO.gif -> ELQO
!EUI8.gif -> EUI8
F!F5ZK.gif -> F5JC
!FJXS.gif -> FJXS
!FPHS.gif -> FPHS
!FRPS.gif -> FRPS
F!FZM8.gif -> FZWH
!G6EO.gif -> G6EO
!GCY8.gif -> GCY8
!GHRK.gif -> GHRK
!GO28.gif -> GO28
!HPYO.gif -> HPYO
F!HT1S.gif -> HT15
!IUGG.gif -> IUGG
F!IYWG.gif -> DDVC
!J5XS.gif -> J5XS
!JZGO.gif -> JZGO
!KLSG.gif -> KLSG
!KPZK.gif -> KPZK
F!LNWW.gif -> ADVW
!LPAO.gif -> LPAO
!LRE8.gif -> LRE8
!M58O.gif -> M58O
!MLE8.gif -> MLE8
!MMI8.gif -> MMI8
!MNHS.gif -> MNHS
!MQ34.gif -> MQ34
!N93K.gif -> N93K
!NO34.gif -> NO34
!OBHS.gif -> OBHS
!OI55.gif -> OI55
!P1OO.gif -> P1OO
!Q1U8.gif -> Q1U8
F!QCTS.gif -> QC7S
!QG5S.gif -> QG5S
!R1IO.gif -> R1IO
F!R5CG.gif -> RSCG
F!RCOG.gif -> MC77
!RCVK.gif -> RCVK
F!RL9S.gif -> RL95
!RLWO.gif -> RLWO
F!RXHS.gif -> RXHB
!SAKW.gif -> SAKW
!SG9C.gif -> SG9C
!SJGW.gif -> SJGW
!T1V4.gif -> T1V4
!U1WW.gif -> U1WW
!V18O.gif -> V18O
!V8OG.gif -> V8OG
!VAUO.gif -> VAUO
!VK8G.gif -> VK8G
!VQNK.gif -> VQNK
!W6GG.gif -> W6GG
!WBWO.gif -> WBWO
!WHGO.gif -> WHGO
!WNQO.gif -> WNQO
F!WY4O.gif -> WY1C
!X8CW.gif -> X8CW
F!XOCO.gif -> AS77
!XPN4.gif -> XPN4
!Y434.gif -> Y434
!Y6B4.gif -> Y6B4
!YH68.gif -> YH68
!YU9C.gif -> YU9C
F!YUI8.gif -> YUE6


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