[Insight-developers] towards fixing bug: 9212: Exception when reading 3D image into a 2D image

[Bradley Lowekamp]

Hello,

I submitted an experimental build using ImageIOBase::GetPixelSize() in  
ImageFileReader::GenderateData:

http://www.cdash.org/CDash/viewTest.php?onlyfailed&buildid=367033

It appears that this error is caused by some classes overloading the  
Get methods, while others just set the internal variable. Combined  
with the ImageIOBase inconsistently accessing these ivars with either  
Get methods or direct access, it would appear the GetPixel methods  
should not be made public.

The previous method used by ImageFileReader to calculate the buffer  
ImageIOBase::GetImageSizeInBytes():
ImageIOBase::SizeType
ImageIOBase
::GetImageSizeInBytes () const
{
   return (this->GetImageSizeInComponents() * this->GetComponentSize());
}

So perhaps it's be to just expose:

ImageIOBase::GetComponentSize();

and NOT expose:

ImageIOBase::GetPixelSize();

since the later was not used before, and the prior appears to have  
been consistently used before.

Brad


On Jun 29, 2009, at 10:04 AM, Lowekamp, Bradley (NIH/NLM/LHC) [C] wrote:

> Hello,
>
> 	I am working on fixing the bug. In ImageFileReader I need to  
> calculate the size of the IO buffer based on the IORegion, and I am  
> missing some function or access to the information I need. I am  
> proposing adding public methods to ImageIORegion and ImageIOBase:
>
> 1)
>
>   /** Get the number of pixels contained in this region. This just
>    * multiplies the size components. */
>   unsigned long itk::ImageIORegion::GetNumberOfPixels( void ) const;
>
> This methods is just copied from the ImageRegion.
>
> 2)
>
> To calculate the buffer size I need the number of pixels and the  
> size of the pixels (or the size of the components and the number of  
> components). Currently, the methods ImageIOBase::GetPixelStride is  
> public, but this methods need to have ComputeStride called for it it  
> be useful. ( I actually think this methods should still be  
> private ). We already have GetNumberOfComponents,  
> GetImageSizeInBytes, GetImageSizeInPixels, and
> GetImageSizeInComponents. But no way to access the size of a pixel  
> or component (unless you for GetImageSizeInBytes/ 
> GetImageSizeInPixels, ick). I propose changing the following methods  
> from protected to public:
>
>   /** Compute the size (in bytes) of the pixel. For
>    * example, and RGB pixel of unsigned char would have size 3  
> bytes. */
>   virtual unsigned int GetPixelSize() const;
>
>   /** Compute the size (in bytes) of the components of a pixel. For
>    * example, and RGB pixel of unsigned char would have a
>    * component size of 1 byte. This method can be invoked only after
>    * the component type is set. */
>   virtual unsigned int GetComponentSize() const;
>
>
> Thanks for your comments,
> Brad
>
>
>
>
>
> ========================================================
> Bradley Lowekamp
> Lockheed Martin Contractor for
> Office of High Performance Computing and Communications
> National Library of Medicine
> blowekamp at mail.nih.gov
>
>
> <ATT00001.txt>

========================================================
Bradley Lowekamp
Lockheed Martin Contractor for
Office of High Performance Computing and Communications
National Library of Medicine
blowekamp at mail.nih.gov


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