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

[Jean-Pierre Roux]

Pechin Lo wrote:

Hi, Pechin.
Sorry for the noise.
I looked at the wrong error log  :-(
Mathieu fixed definitively the lossless JPEG compression several weeks ago.

So, using last version, you shouldn't have the error.
Jean-Pierre

> 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 
> <mailto: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>
>     > <mailto: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>
>     >     <mailto: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
>     >
>     ------------------------------------------------------------------------
>
>     >
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>
>
>
> -- 
> 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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