1.查表法伪彩图映射

图像彩色映射的原理是首先生成一个颜色查找表，然后根据图像的一个标量值向颜色查找表中查找对应的颜色，并用新颜色值替代原来的像素值。VTK中vtkImageMapToColors负责图像彩色映射，vtkLookUpTable负责生成颜色查找表。

下面代码说明了怎样进行彩色映射：

 1 #include <vtkAutoInit.h>
 2 VTK_MODULE_INIT(vtkRenderingOpenGL);
 3  
 4 #include <vtkSmartPointer.h>
 5 #include <vtkJPEGReader.h>
 6 #include <vtkLookupTable.h>
 7 #include <vtkImageMapToColors.h>
 8 #include <vtkImageActor.h>
 9 #include <vtkRenderer.h>
10 #include <vtkRenderWindow.h>
11 #include <vtkRenderWindowInteractor.h>
12 #include <vtkInteractorStyleImage.h>
13 int main()
14 {
15     vtkSmartPointer<vtkJPEGReader> reader =
16         vtkSmartPointer<vtkJPEGReader>::New();
17     reader->SetFileName("lena-gray.jpg");
18     //建立颜色映射查找表
19     vtkSmartPointer<vtkLookupTable> colorTable =
20         vtkSmartPointer<vtkLookupTable>::New();
21     colorTable->SetRange(0.0, 255.0);
22     colorTable->SetHueRange(0.1, 0.5);
23     colorTable->SetValueRange(0.6, 1.0);
24     colorTable->Build();
25     //建立颜色映射
26     vtkSmartPointer<vtkImageMapToColors> colorMap =
27         vtkSmartPointer<vtkImageMapToColors>::New();
28     colorMap->SetInputConnection(reader->GetOutputPort());
29     colorMap->SetLookupTable(colorTable);
30     colorMap->Update();
31     //建立演员
32     vtkSmartPointer<vtkImageActor> origActor =
33         vtkSmartPointer<vtkImageActor>::New();
34     origActor->SetInputData(reader->GetOutput());
35  
36     vtkSmartPointer<vtkImageActor> colorActor =
37         vtkSmartPointer<vtkImageActor>::New();
38     colorActor->SetInputData(colorMap->GetOutput());
39     //化妆
40     double origView[4] = { 0.0, 0.0, 0.5, 1.0 };
41     double colorView[4] = { 0.5, 0.0, 1.0, 1.0 };
42     vtkSmartPointer<vtkRenderer> origRender =
43         vtkSmartPointer<vtkRenderer>::New();
44     origRender->SetViewport(origView);
45     origRender->AddActor(origActor);
46     origRender->ResetCamera();
47     origRender->SetBackground(1.0, 0.0, 0.0);
48  
49     vtkSmartPointer<vtkRenderer> colorRender =
50         vtkSmartPointer<vtkRenderer>::New();
51     colorRender->SetViewport(colorView);
52     colorRender->AddActor(colorActor);
53     colorRender->ResetCamera();
54     colorRender->SetBackground(0.0, 0.0, 0.0);
55     //舞台
56     vtkSmartPointer<vtkRenderWindow> renderwindow =
57         vtkSmartPointer<vtkRenderWindow>::New();
58     renderwindow->AddRenderer(origRender);
59     renderwindow->AddRenderer(colorRender);
60     renderwindow->SetSize(640, 320);
61     renderwindow->SetWindowName("GrayToColor");
62     //设置交互
63     vtkSmartPointer<vtkRenderWindowInteractor> rwi =
64         vtkSmartPointer<vtkRenderWindowInteractor>::New();
65     vtkSmartPointer<vtkInteractorStyleImage> style =
66         vtkSmartPointer<vtkInteractorStyleImage>::New();
67     rwi->SetInteractorStyle(style);
68     rwi->SetRenderWindow(renderwindow);
69     rwi->Initialize();
70  
71     rwi->Start();
72     return 0;
73 }