[vtkusers] Improve image quality when using vtkResliceCursorWidget

[Enzo Matsumiya]

Hi David.

Cubic interpolation did it.
I'll take a look into Sinc again in the future.


Thank you.


> On Jun 23, 2016, at 11:25, David Gobbi <david.gobbi at gmail.com> wrote:
> 
> Hi Enzo,
> 
> The artifact might be due to this bug, which was recently fixed in the master branch:
> 
> https://gitlab.kitware.com/vtk/vtk/merge_requests/1279 <https://gitlab.kitware.com/vtk/vtk/merge_requests/1279>
> 
> Cubic interpolation is much faster than Sinc.
> 
>  - David
> 
> 
> 
> 
> On Thu, Jun 23, 2016 at 7:34 AM, Enzo Matsumiya <enzo.matsumiya at gmail.com <mailto:enzo.matsumiya at gmail.com>> wrote:
> Hi,
> 
> I got the result I wanted (quality-wise) adding a vtkImageSincInterpolator to the image reslice within vtkResliceCursorRepresentation. I think the default was using the nearest neighbor algorithm.
> 
> But now I have 2 problems:
> 
> - The performance decrease was huge. Is there any way to improve that?
> - Here are 2 images showing my second issue. There are artifacts *only* in orthogonal slices, and also only in coronal and sagittal. The artifacts are gone when I oblique reslice:
> 
> http://oi65.tinypic.com/dcga2x.jpg <http://oi65.tinypic.com/dcga2x.jpg> - with artifacts
> http://oi64.tinypic.com/30cuoug.jpg <http://oi64.tinypic.com/30cuoug.jpg> - oblique reslicing, without artifacts
> 
> I'm guessing it's a bug in the interpolator because it really looks like some mathematical bug, but I could be wrong of course.
> 
> 
> Can anyone help me out?
> 
> 
>> On Jun 22, 2016, at 12:24, Enzo Matsumiya <enzo.matsumiya at gmail.com <mailto:enzo.matsumiya at gmail.com>> wrote:
>> 
>> Hi Sankhesh,
>> 
>> Thanks for the reply.
>> 
>> By quality I mean that the first image looks crispy, while the second one looks very smooth.
>> But now that you said, I will see if I can find any data type inconsistency accross my code.
>> 
>> ManageWindowLevel is enabled on vtkResliceCursorWidget.
>> 
>> 
>> Thanks again,
>> 
>> Enzo
>> 
>> 
>>> On Jun 22, 2016, at 11:59, Sankhesh Jhaveri <sankhesh.jhaveri at kitware.com <mailto:sankhesh.jhaveri at kitware.com>> wrote:
>>> 
>>> Enzo,
>>> 
>>> What do you mean by quality?
>>> 
>>> Looking at the two images, the resolution looks the same to me. I see there is a difference in the range of pixel values between the two images. This could either be due to the data type differences in the output image or actual data value differences. Do you have ManageWindowLevel enabled for vtkResliceCursorWidget?
>>> 
>>> Sankhesh
>>> 
>>>  
>>> 
>>> On Wed, Jun 22, 2016 at 10:49 AM, Enzo Matsumiya <enzo.matsumiya at gmail.com <mailto:enzo.matsumiya at gmail.com>> wrote:
>>> Hi,
>>> 
>>> I'm using vtkResliceCursorWidget for oblique reslicing on a CT set.
>>> But I'm getting really bad image quality. Here is an example from my app:
>>> 
>>> http://oi68.tinypic.com/1z55cop.jpg <http://oi68.tinypic.com/1z55cop.jpg>
>>> 
>>> And here is one (although non-oblique) from other software:
>>> 
>>> http://oi68.tinypic.com/2lidi6p.jpg <http://oi68.tinypic.com/2lidi6p.jpg>
>>> 
>>> I would like to know if there's a way to improve the quality on my app.
>>> 
>>> 
>>> Thanks
>>> 
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>> 
> 
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