[Insight-users] Re: Problem with lossless JPEG compression in GDCMImageIO

[Pechin Lo]

Hi,

Regarding the binary images, the way I get it is by loading a random dicom
file, obtain the output (which is of class itk::Image). After that I just
change a row (position and width set arbitrary) to a value of n (again
arbitrary chosen) and the rest to n+1 in the data.
Finally save the modified image into a new dicom file.

In another words I don't really have any phantom files.
Do mail me personally if you still want it, I'll try to rewrite the code to
generate the file as I sort of overwritten my testing code...

Regards,
Pechin

On 9/25/07, Jean-Pierre Roux <jpr at creatis.insa-lyon.fr> wrote:
>
> Pechin Lo wrote:
> > I'm using ITK 3.2.0
> > Should I switch to 3.4 and try again?
>
> I'm afraid it will not change a lot.
> In the very last version a gdcm, for a few images, we have, after
> compression/decompression a few pixels that differs from +/-1 ...
> Could you send me one of your 'binary images' that only consists of n
> and n+, to see if we can track the bug?
> Thx
> Jean-Pierre Roux
> >
> > On 9/25/07, *Mathieu Malaterre* <mathieu.malaterre at gmail.com
> > <mailto:mathieu.malaterre at gmail.com>> wrote:
> >
> >     On 9/25/07, Steve M. Robbins <steve at sumost.ca
> >     <mailto:steve at sumost.ca>> wrote:
> >     > On Mon, Sep 24, 2007 at 11:50:05PM +0200, Pechin Lo wrote:
> >     > > After some tweaking around, I found out that JPEG compression
> >     works provided
> >     > > that the minimum difference between two pixels is 2.
> >     > > For example, if I have an image that only consists of n and
> >     n+1, the saved
> >     > > image will only contains the value n.
> >     > > However, if the image consists of value n and n+2, then the
> >     saved image will
> >     > > contains both n and n+2.
> >     > > In other words, the image will stores fine if I multiply it by
> >     a factor of
> >     > > 2.
> >     > >
> >     > > Can someone please tell me why is this happening?
> >     >
> >     > I'm not familiar with the code in question, but is it possible
> >     > that you're using a lossy JPEG compression?
> >
> >     Hi all,
> >
> >
> >       Could you please let me know if you are using ITK 3.2 / ITK 3.4
> >     or CVS ?
> >
> >     Thanks
> >
> >     --
> >     Mathieu
> >     Ps: 3.4 and CVS should *not* produce this weird behavior.
> >
> >
> >
> >
> > --
> > Pechin Lo Chien Pau
> > Ph.d. Student
> > Department of Computer Science (DIKU)
> > University of Copenhagen
> > Universitetsparken 1, Office S226
> > DK-2100 Copenhagen, Denmark
> > Phone: +45 3532 1433
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Insight-users mailing list
> > Insight-users at itk.org
> > http://www.itk.org/mailman/listinfo/insight-users
> >
>



-- 
Pechin Lo Chien Pau
Ph.d. Student
Department of Computer Science (DIKU)
University of Copenhagen
Universitetsparken 1, Office S226
DK-2100 Copenhagen, Denmark
Phone: +45 3532 1433
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