[vtkusers] Improve image quality when using vtkResliceCursorWidget

[David Gobbi]

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

Cubic interpolation is much faster than Sinc.

 - David




On Thu, Jun 23, 2016 at 7:34 AM, Enzo Matsumiya <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 - with artifacts
> 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>
> 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>
> 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
> > 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
>>
>> And here is one (although non-oblique) from other software:
>>
>> 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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