# Need to convert color dicom to grayscale

**URL:** <https://discourse.slicer.org/t/need-to-convert-color-dicom-to-grayscale/3590>\
**Category:** Support\
**Tags:** dicom, volume, file-import\
**Created:** [July 27, 2018, 2:04am UTC](https://discourse.slicer.org/t/need-to-convert-color-dicom-to-grayscale/3590 "2018-07-27T02:04:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![travesty82](https://avatars.discourse-cdn.com/v4/letter/t/3da27b/32.png) [@travesty82](https://discourse.slicer.org/u/travesty82)\
**Post date:** [July 27, 2018, 2:04am UTC](https://discourse.slicer.org/t/need-to-convert-color-dicom-to-grayscale/3590/1 "2018-07-27T02:04:01Z")

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Operating system: Windows 7  
Slicer version: 4.8.1  
Expected behavior: Convert to grayscale  
Actual behavior: Cannot load as a scalar volume

I have PET images that I want to get the SUV values from certain ROIs. However, I cannot load the DICOMs in because they are RGB instead of grayscale. Is there a way to convert this to grayscale? So far I see the “Vector to Scalar Volume” module, but this appears to be for images (.jpg, .png, etc).

I converted my PET to grayscale in MATLAB but I am not confident in the transfer back to Slicer. Is there an easier in-house method for the DICOM files?

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [July 27, 2018, 2:34pm UTC](https://discourse.slicer.org/t/need-to-convert-color-dicom-to-grayscale/3590/2 "2018-07-27T14:34:18Z")

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How did you end up with RGB PET images? I suspect they might be secondary captures or other be non-original data and you may not be able to get SUV values out, at least not with the standard tools.

There’s a lot of detail about the kind of PET DICOM Slicer expects, for example in this paper:

> **[DICOM for quantitative imaging biomarker development: a standards based...](https://peerj.com/articles/2057/)**
>
> Background. Imaging biomarkers hold tremendous promise for precision medicine clinical applications. Development of such biomarkers relies heavily on image post-processing tools for automated image quantitation. Their deployment in the context of...

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**Author:** ![fedorov](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/fedorov/32/14_2.png) [@fedorov](https://discourse.slicer.org/u/fedorov)\
**Post date:** [July 27, 2018, 2:47pm UTC](https://discourse.slicer.org/t/need-to-convert-color-dicom-to-grayscale/3590/3 "2018-07-27T14:47:18Z")

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Chances are, your DICOM files are secondary captures, and this probably means you won’t be able to use them for quantitation.

It would be difficult to know more without looking at the data.

If you share the data, remember that it is your responsibility to ensure it does not contain patient identifiable information and you are in compliance with the applicable patient privacy rules.

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**Author:** ![travesty82](https://avatars.discourse-cdn.com/v4/letter/t/3da27b/32.png) [@travesty82](https://discourse.slicer.org/u/travesty82)\
**Post date:** [July 27, 2018, 3:34pm UTC](https://discourse.slicer.org/t/need-to-convert-color-dicom-to-grayscale/3590/4 "2018-07-27T15:34:48Z")

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Thank you. I will ask the radiologist about this. If this is the case, hopefully I can get the original data.

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**Author:** ![travesty82](https://avatars.discourse-cdn.com/v4/letter/t/3da27b/32.png) [@travesty82](https://discourse.slicer.org/u/travesty82)\
**Post date:** [July 27, 2018, 3:36pm UTC](https://discourse.slicer.org/t/need-to-convert-color-dicom-to-grayscale/3590/5 "2018-07-27T15:36:31Z")

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Thank you. I will investigate. I would like to share for more clarity, and will anonymize the DICOMs if I share them.