[vtkusers] How to map negative grayscale to color?

[Liu_tj]

Thanks David for your great help. I will try it.





在2016-03-08，"David Gobbi" <david.gobbi at gmail.com> 写道： -----原始邮件-----
发件人:"David Gobbi" <david.gobbi at gmail.com>
发送时间:2016年03月8日 星期二
收件人:"Liu_tj" <tjlp at netease.com>
抄送:"vtkusers" <vtkusers at vtk.org>
主题:Re: [vtkusers] How to map negative grayscale to color?


Hi Liu Peng,


You can set individual values in the lookup table,
in order to precisely map certain scalar values to
specific colors:


table->SetRange(-1024, 4095);
table->SetNumberOfTableValues(4095 + 1024 + 1);
for (int i = -1024; i < -10; i++) {
    table->SetTableValue(0.0, 0.0, 0.0, 1.0);
}
for (int i = -10; i <= 200; i++) {
    table->SetTableValue(0.0, 1.0, 0.0, 1.0);
}
etcetera.


 - David




On Mon, Mar 7, 2016 at 9:31 AM, Liu_tj <tjlp at netease.com> wrote:

Hi,

I try to use the vtkLookupTable to convert the grayscale to rgb color. The image scalar range is [-1024,3071] returned by vtkImageData::GetScalarRange(). Now I want to convert specific grayscale range, for example, [-10,200] to one color, such as green (RGB is 0,1,0). How to do that by vtkLookupTable? I have no idea what method should call: SetNumberOfTableValues(), SetRange(), SetHueRange(), SetValueRange(). What do "Hue" and "Value" stand for?

BR,
Liu Peng


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