[Insight-users] Reading series of images

[Miller, James V (Research)]

Files are queried multiple times when read.

First there is pass via the factor mechanism to determine which type
of format the file is.  A set of ImageIO each peek at the file and 
determine whether the file is a format it can read. In simple cases, 
we simply trigger off the extension.  But usually, the ImageIO objects
look for a magic number of try to read the complete header to determine
whether the file is a format it can read.

Once an ImageIO is found that can read the file, the reader will read the
file's  meta data.  This a subset of the information that is usually in the
header of file.  Things like pixel type, rows and columns, etc.

Finally, the bulk data (pixel data) is read.

I suspect you are seeing the filenames once for meta-information and once
for the bulk data.



-----Original Message-----
From: Toon Huysmans [mailto:denhuys at hotmail.com]
Sent: Friday, April 09, 2004 9:12 AM
To: insight-users at itk.org
Subject: Re: [Insight-users] Reading series of images


Hello Luis,

    I am reading a mhd file, refering to slices in BMP format.

    I only suspect that the slices are read twice, I don`t any code that
acknowledges that.
    But when reading such a mhd file, using itk::ImageFileReader, the
file-name of each slice is output to the console.
    And since the series of slide-filenames is output twice, I suspect the
that the slices are read twice.


        typedef itk::ImageFileReader<ImageType> ReaderType;
        ReaderType::Pointer reader = ReaderType::New();
        const char *filename = "F:/thing.mhd";
        reader->SetFileName( filename );
        reader->Update();

Hope I am specific enough,
Thanks,

Toon.


----- Original Message ----- 
From: "Luis Ibanez" <luis.ibanez at kitware.com>
To: "Toon Huysmans" <denhuys at hotmail.com>
Cc: <insight-users at itk.org>
Sent: Friday, April 09, 2004 2:33 PM
Subject: Re: [Insight-users] Reading series of images


>
> Hi Toon,
>
>
> Could you please be more specific with your question ?
>
>
> By   "ImageReader", do you mean:
>
> A) the class itk::ImageFileReader   ?
>
>     or
>
> B) one of the examples in Insight/Examples/IO
>
>     or
>
> C) something else ?
>
>
>
> Also, what make you suspect that slices are being
> read twice ?  are you running this in a debugger ?
> and seeing twice the invokation of a particular function ?
> if so, what function do you see invoked twice ?
>
>
> Can you post a minimal code example where you
> observe such behavior ?
>
> What image fileformat where you reading when you
> noticed such effect  ?
>
>
>
>    Thanks,
>
>
>      Luis
>
>
> --------------------
> Toon Huysmans wrote:
>
> > Hi,
> >
> >     I`ve got q small question:  Why does ImageReader seem to read every
> > slice two times.  In a first pass, the images are read in slow, the
> > second pass is fater. any ideas?
> >
> > Toon.
>
>
>
>
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