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  1. Xref: sparky comp.sys.next.software:2680 comp.sys.next.misc:22054
  2. Newsgroups: comp.sys.next.software,comp.sys.next.misc
  3. Path: sparky!uunet!caen!saimiri.primate.wisc.edu!usenet.coe.montana.edu!pcnot4me
  4. From: pcnot4me@cs.montana.edu (Craig Pratt)
  5. Subject: Bug in JPEG routine ?
  6. Message-ID: <1992Nov17.045103.20652@coe.montana.edu>
  7. Sender: usenet@coe.montana.edu (USENET News System)
  8. Reply-To: pcnot4me@cs.montana.edu (Craig Pratt)
  9. Organization: Dept. of Computer Science, MSU, Bozeman Mt 59717
  10. Date: Tue, 17 Nov 1992 04:51:03 GMT
  11. Lines: 170
  12.  
  13. Howdy all!
  14.  
  15. A 24-bit TIFF image I've been messing with seems to have uncovered a
  16. bug in Next's JPEG compression routine.  The image was created with a
  17. ray tracer and contains a large number of red shades.  When I save it
  18. as a JPEG TIFF out of GraphicsWorkshop (thanks to Alex Raftis) or run
  19. it through tiffutil, the resulting image has a major problem.  The
  20. brightest shade of red is transformed into a nasty green color.  This
  21. happens in whatever program I bring it into, leading me to believe
  22. that it's a problem with the underlying routine not the application
  23. programs.
  24.  
  25. Has anyone else run into this?
  26.  
  27. Here's a miniature of the uuencoded LZW-compressed TIFF that illustrates 
  28. the problem: (sorry about the BW, but I think this is important)  (sorry
  29. again that this isn't in NewsGrazer, but I'm not directly on the net, 
  30. unfortunately)
  31.  
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  165. M6LM9ELZB=KE \&PB\MHV$C(>3X=X0D 4_H*OH+4M$"("H\SHH2YL@P#0<T-9
  166. M^'!<B;UE3DGP^.A(X"%EHFU-J'XEU 4%(1,&8M":$T7(7.V%4\97$*E\ NE]
  167. M"2'49IM#^G)# 0+*I%3ZDCD9VH1:H08 2 )]4^J!4NFHF%Z$0JY2,C*CR%5H
  168. M(R[0C0,E\D1 &[4$:I5%5U4/75   UU5[(>MMY3M$K$2 %6ZP@,D]EC>]8FQ
  169. M((%.$'K17JO=D9U$(:57\$0,J!KI7Q9NPI!B @ - 0   P    $ 9    0$ 
  170. M P    $ 2@   0(  P    ,  !BF 0,  P    $ !0   08  P    $  @  
  171. M 1$ !     ,  !BL 14  P    $  P   18 !     $   */ 1< !     , 
  172. M !BX 1H !0    $  !C$ 1L !0    $  !C, 1P  P    $  @   2@  P  
  173. M  $  @         $  0 !     @   R5   2*0  #(T   64   %VP *_(  
  174. + "<0  K\@   )Q $
  175.  
  176. end
  177.  
  178. -- 
  179.   Craig Pratt                                          pcnot4me@cs.montana.edu
  180.   Montana State University, Bozeman MT            gcp1070@msu.oscs.montana.edu
  181.    What's the difference between a used-car salesman and a computer salesman?
  182.        A used-car salesman knows when he is lying. - Andrew Loewenstern
  183.