# Problem when cropping! \>\> Transparent slices

**URL:** <https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553>\
**Category:** Support\
**Created:** [July 12, 2019, 4:19pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553 "2019-07-12T16:19:22Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [July 12, 2019, 4:19pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/1 "2019-07-12T16:19:22Z")

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So i have loaded a bunch of .pngs as a sequence into slicer…

When I dragged the first png onto the slicer window\>\> it offered me a pop up window where I chose\>\> show options\>\>\> then unchecked the little box that says single file\>\> Then I chose fullrainbow next to it (maybe I should choose only rainbow and not the fullrainbow?!).

Either way once I click okay, the pngs load as a sequence and I can see them. I transform them a little bit, I flip the vertical axis (it is sadly upside down) and then I proceed to crop it.

The problem? When I crop a part of the volume\>\> the pngs seem to overaly each other and become transparent to a certain degree. So one always sees 2 pngs both somewhat transparent.

The hell?!  
I use crop volume to crop it.

Then I close everything open the slicer again and load the sequence and this time before cropping it, I move the bar in the red perspective (coronary) all the way to the lowest slice and then move the bar a little bit right and then\>\>\> they suddenly appear transparent again!! :S CATASTORPHY!

WHy would they not look transparent but then when I pull the bar and go to the lowest slice and then move back they become \>\> transparent. What the hell?

Then I tried to not do that and just don’t scroll to the lowest slice, instead I make sure that they are not transparent and then\>\> crop the volume.

Problem\>\>\> on the cropped volume they still look transparent.

No matter what I do with the cropped volume, they remain cropped. I tried translation, move it it half a slice up, half a slice down, I tried scrolling it back to the beginning and scrolling it to the end. Nothing works… they remain cropped and transparent. What the hell?!

Hmm…

I must submit my project soon so this is very very scary now I might nor be able to solve it.

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [July 12, 2019, 4:24pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/2 "2019-07-12T16:24:54Z")

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Could you add a few screenshots so that we can better understand what’s happening?

Can you give a bit higher-level view of what you are trying to achieve?

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [July 12, 2019, 4:25pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/3 "2019-07-12T16:25:22Z")

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good idea! God bless you Andras, I’ve seen you help so many people on this forum

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [July 12, 2019, 4:31pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/4 "2019-07-12T16:31:40Z")

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![Screenshot_1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/b/6/b6fc1459a77b5674a821366f202929e3a9242fd9.jpeg) ![Screenshot_2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/8/98d5e97474bc11bf6c62bb91d72a7e5e0dc17124.jpeg)

Here I have took a screenshot… If I delete number 5 up there it clears up and I see only one image.

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [July 12, 2019, 5:03pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/5 "2019-07-12T17:03:52Z")

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What you see is the effect of interpolation between adjacent slices (when you move the slice slider to a position between two slices then there is a gradual fading between them). You can disable interpolation by unchecking “Interpolate” in Volumes module.

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [July 12, 2019, 5:30pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/6 "2019-07-12T17:30:20Z")

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Indeed, unchecking interpolation makes images non-transparent and everything is beautiful.

However\>\>\> cropping the volume still produced transparent volumes and no matter what i do with the cropped volume, I get them transparent (they remain transparent for the cropped volume, even after I turn off the interpolation.

Hmm

btw thank you so much for replying, I am puzzled how much you are helpful and help people out! Amazing

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**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [July 12, 2019, 5:45pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/7 "2019-07-12T17:45:12Z")

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Ohhh I just realized in cropping menu it says “interpolated cropping”… that one unchecked, crops the image perfectly without fusing them or making them transparent…

I wonder what is this feature interpolation is used at all

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [July 12, 2019, 6:15pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/8 "2019-07-12T18:15:37Z")

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Normally, slices are spatially related, so when you are in between two slices then you want to see the a weighted average of the two closest slices. Most probably your image is not a real 3D volume (2D slices are misaligned, there are burnt-in 2D annotations, etc.) and that’s why interpolation is not desirable for visualization.

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<div class="post-metadata">

**Author:** ![NoobForSlicer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/noobforslicer/32/10900_2.png) [@NoobForSlicer](https://discourse.slicer.org/u/NoobForSlicer)\
**Post date:** [July 12, 2019, 6:35pm UTC](https://discourse.slicer.org/t/problem-when-cropping-transparent-slices/7553/9 "2019-07-12T18:35:14Z")

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Thank you so much Lasso \<3 You are life savior!

I will ask one more question in the forum **I hope I am not annoying with the questions**. It is not related to this issue so I will post it as a new thread.

Thank you soo so much!  
Learning about slicer over and over and I’ve seen your answers in so many questions and wonderful explanations Lasso!