# volume rendering independent component color problem

**URL:** https://discourse.vtk.org/t/volume-rendering-independent-component-color-problem/7989
**Category:** Support
**Created:** [March 6, 2022, 2:08pm UTC](https://discourse.vtk.org/t/volume-rendering-independent-component-color-problem/7989 "2022-03-06T14:08:09Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Mohamed\_Zidan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/mohamed_zidan/32/4795_2.png) [@Mohamed\_Zidan](https://discourse.vtk.org/u/Mohamed_Zidan)
#### Post date: [March 6, 2022, 2:08pm UTC](https://discourse.vtk.org/t/volume-rendering-independent-component-color-problem/7989/1 "2022-03-06T14:08:09Z")

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Hello,  
I am using independent component with vtkOpenGLGPUVolumeRayCastMapper or vtkGPUVolumeRayCastMapper to represent the volume and the labels.  
vtk version is 9.1

the first independent component is the labels and its value is :

- 0 if no label , color set to white
- 1 ia a yellow label
- 2 ia a blue label

the second component is the volume

I have problem with the labels colors , if i set the first label opacity to 0 the second label appear fine

 ![Screenshot (20)](https://discourse.vtk.org/uploads/default/original/2X/c/ce110b0bb34f5bd44f18661e766d3d8eceb631cf.png)

if the first label opacity is set to 1 both labels appear yellow as the first one, even if second label opacity set to 0

 ![Screenshot (22)](https://discourse.vtk.org/uploads/default/original/2X/7/78d361399fec70de2e0fd728682d153b0f45300e.png)

I noticed that while interacting with volume the color keep changing ,  
the first label change between white and yellow  
the second one change between yellow , blue and white