[Insight-developers] [Fwd: Changes to MetaImage...]

[Daniel J. Blezek, Ph.D.]

Stephen and Parag,

  This exact issue drove the discussion about file reading and writing at
last week's telephone conference.  I have several ideas in mind as to
finding images and writing images for regression testing, but have not
made them happen just yet.  In the mean time, I would welcome any
suggestions you may have as to how to address this issue.  In our
experience with VTK, which may be different for ITK, some platforms
require a platform specific "gold image", and require special processing.


Here are some of my ideas, strictly related to regression testing:

-  Have a Toolkit similar to Java, so to get the name of a file you would
do something like this:

    std::string s = Toolkit::GetFileName ( "VHF/Head.png" );

    The Toolkit would properly expand the file name to be the path to the
image you want, allowing images to be stored on fixed media(CDROM).  On
the outbound side, you would request an output image in a similar manner:

    std::string s = Toolkit::GetImageTestResultFileName (
"itkFileIOMetaImageTest" );

    The Toolkit would expand this name to a directory where test images
sit, and a latter process would pick up the images and compare them to the
"gold standard".  If the test were run in an example mode, it would simply
write the output in the current directory, for the user to take a look at
later.


- This raises the issue of file formats yet again.  Everyone seems to cook
up their own file format to meet the needs of whatever problem they have
at hand! (We are no exception...)  In my view, the current problem at hand
is regression testing.  I've given this issue some thought.  We need:

  - a file format that is easily displayed locally and through a browser
  - a format that is easily created by all Insight developers
  - a format that has 2D support at minimum
  - a format that supports as many common datatypes as possible

The first point drives the selection down considerably.  The only real
canidates are Gif, Jpeg, and PNG.  Gif and Jpeg are generally lossy
compression, and don't fit the bill.  PNG is a relatively new format, with
good support from most OS/viewers/browsers.  PNG is also licensed for use
in a toolkit such as ITK.  The real downside is that PNG only supports 8
and 16 bit datatypes.  I feel this is acceptable because medical image
data generally comes in these two types, so that should not be a limiting
factor.  PNG support is built and working on my local checkout.

Since I'm doing most of the testing infrastructure, I will offer to serve
as the focal point for this issue, and welcome any suggestions.

Thanks,
-dan


On Thu, 22 Mar 2001, Stephen R. Aylward wrote:

> 
> How should we reference data files in the example directories if the
> build is placing the executables in different directories?  See below
> for more details....
> 
> Thanks,
> Stephen
> 
> Parag Chandra wrote:
> > 
> > Ok, that solves half the problem. I'll put the test and the accompanying
> > files into examples. But how would I reference that (the examples) directory from within
> > the test program? Each platform will place the executable for this test into
> > something like ${CMAKE_BINARY_DIR}/Examples, but ${CMAKE_BINARY_DIR} isn't
> > even an environment variable for me to reference, it's a variable that's
> > internal to CMake. If I reference the file without the pathname, like
> > "TestInput.mhd", then the file has to be in the same directory as the
> > executable, and that means I would have to place a copy of the test file
> > into Insight-Cygwin, Insight-VC++, Insight-Linux, etc. Not only is that
> > redundant, but there's no way I could foresee the additional platforms we
> > might target, and so the test running on those platforms will generate an
> > exception when it can't find the file. The only thing I can see is to place
> > the test file into one directory, and then run the test for each platform
> > from that directory by using the full pathname of the executable, e.g.
> > /Insight-Cygwin/Examples/itkFileIOMetaImageTest.exe. Does anyone have any
> > other ideas?
> > 
> > Thanks,
> > -Parag
> > 
> > ---
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> -- 
> ===============================================
> Stephen R. Aylward
> Assistant Professor of Radiology
> Adjunct Assistant Professor of Computer Science
> http://www.cs.unc.edu/~aylward
> aylward@unc.edu
> (919) 966-9695
> 
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--
Daniel Blezek, Ph.D.
blezek@crd.ge.com
Visualization and Computer Vision Program
Electronic Systems Lab
GE Corporate Research & Development