Best way to visualize a RGB Volume?

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Best way to visualize a RGB Volume?

Willy
Hi,

i want to visualize a RGB Volume and have a little problem. i do not think that there is a perfect solution, but maybe i am missing something.

Here i my problem:

There are three different Methods to visualize a RGB Volume:
1. Method: IndependentComponentsOn: three components (R,G,B), each with Colortransferfunction and opacityfunction
2. Method: IndependentComponentsOff: two components, first with Colortransferfunction and second with opacityfunction
3. Method: IndependentComponentsOff: four components, 1-3(R,G,B) with Colortransferfunction and fourth with opacityfunction

Here are the disadvantages for each Method:
1. Method: It is not possible to create a colorTransferFunction or opacityFunction for the intensity value of a color(voxel), it is only possible to set these functions for each components seperate. This can lead to   falsified colors if the user changes these functions somehow (if you have the same color and opacity function for all components).
2. Method: the two components must have the same data type. the color component needs at least 3 byte, but there is no 3 byte type => 4 bytes for each component => 8 bytes per voxel => huge overhead.  Moreover the image quality for maximum intensity BlendMode is not as good as for the 1. Method. If you have (in the volume)  for example a green wall with value 250 and a red area behind it (for the current camera position) with value 200, you can't see the red area at all. In the first method the red area is displayed as yellow area (that is better).
3. Method: No colorFunction

Is there a Method without disadvantages?

MfG
Ludwig
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Re: Best way to visualize a RGB Volume?

Sankhesh Jhaveri-2

Hi Ludwig,

Just so I understand, you’d like to be able to pass the RGB volume through a color lookup table too?

IMHO, if you have a RGB volume, adding a fourth component for opacity and setting an opacity function with IndependentComponentsOff is the best method.

Note that with two dependent components, the first component values are used to lookup colors from the color transfer function i.e. the first component can be as small as 1 byte (unsigned char).

Hth,
Sankhesh


On Mon, Jul 10, 2017 at 10:47 AM Willy <[hidden email]> wrote:
Hi,

i want to visualize a RGB Volume and have a little problem. i do not think
that there is a perfect solution, but maybe i am missing something.

Here i my problem:

There are three different Methods to visualize a RGB Volume:
1. Method: IndependentComponentsOn: three components (R,G,B), each with
Colortransferfunction and opacityfunction
2. Method: IndependentComponentsOff: two components, first with
Colortransferfunction and second with opacityfunction
3. Method: IndependentComponentsOff: four components, 1-3(R,G,B) with
Colortransferfunction and fourth with opacityfunction

Here are the disadvantages for each Method:
1. Method: It is not possible to create a colorTransferFunction or
opacityFunction for the intensity value of a color(voxel), it is only
possible to set these functions for each components seperate. This can lead
to      falsified colors if the user changes these functions somehow (if you
have the same color and opacity function for all components).
2. Method: the two components must have the same data type. the color
component needs at least 3 byte, but there is no 3 byte type => 4 bytes for
each component => 8 bytes per voxel => huge overhead.  Moreover the image
quality for maximum intensity BlendMode is not as good as for the 1. Method.
If you have (in the volume)  for example a green wall with value 250 and a
red area behind it (for the current camera position) with value 200, you
can't see the red area at all. In the first method the red area is displayed
as yellow area (that is better).
3. Method: No colorFunction

Is there a Method without disadvantages?

MfG
Ludwig



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Re: Best way to visualize a RGB Volume?

Willy
two components: if i use 1 byte for the first component i can only see 256 different colors, but i have  2^16 colors. I would need 8 byte to display that (4 per component)
four components: just 4 bytes in total, but no color function.
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