//先读取图像，别忘了update

//获取图像维度，二维的dims[2]值为1
int dims[3];
reader->GetOutput()->GetDimensions(dims);

//获取图像原点
double origin[3];
reader->GetOutput()->GetOrigin(origin);

//获取像素间隔
double spaceing[3];
reader->GetOutput()->GetSpacing(spaceing);

auto changer =vtkSmartPointer<vtkImageChangeInformation>::New();
//这里只是传递数据，并没有管道连接，故需update
changer->SetInput(reader->GetOutput());

//修改图像原点
changer->SetOutputOrigin(100, 100, 0);

//修改像素间隔
changer->SetOutputSpacing(5,5,1);

//将原点修改为图像中点，会覆盖SetOutputOrigin()
changer->SetCenterImage(1);

changer->Update();

//之后获取信息就要从changer里获取了，因为数据已经传到changer里了
changer->GetOutput();

//千万别忘了update

//获取维度，用于迭代
int dims[3];
reader->GetOutput()->GetDimensions(dims);

//获取像素的元组组分数(判断是灰度图,梯形图,RGB图)
int nbOfComp;
nbOfComp = reader->GetOutput()->GetNumberOfScalarComponents();

for (int k = 0; k < dims[2]; k++) {
	for (int j = 0; j < dims[1]; j++) {
		for (int i = 0; i < dims[0]; i++) {
			//返回的是void指针,需要根据实际属性类型进行强制转换
			unsigned char *pixel = static_cast<unsigned char *>(reader->GetOutput()->GetScalarPointer(i, j, k));

			//对元组内的元素进行操作
			*pixel;
			*(pixel + 1);
			*(pixel + 2);
		}
	}
}

//定义一个子区域，用于指定要迭代的区域
int subRegion[6] = {0, 300, 0, 300, 0, 0};
vtkImageIterator<unsigned char> it(reader->GetOutput(), subRegion);

while (!it.IsAtEnd()) {

    //获取tuple的指针，分别指向开始和结尾处
    unsigned char *inSI = it.BeginSpan();
    unsigned char *inSIEnd = it.EndSpan();

    while (inSI != inSIEnd) {

        //操作这个像素中的某个属性值
        ++inSI;
    }
    it.NextSpan();
}

auto shift = vtkSmartPointer<vtkImageShiftScale>::New();
shift->SetInputData((vtkDataObject *)reader->GetOutput());
shift->SetOutputScalarTypeToUnsignedChar();
//设置偏移量
shift->SetShift(1);
//设置缩放值
shift->SetScale(127.5);
shift->Update();

auto luminanceFilter = vtkSmartPointer<vtkImageLuminance>::New();
luminanceFilter->SetInputData(reader->GetOutput());
luminanceFilter->Update();

auto extractRedFilter = vtkSmartPointer<vtkImageExtractComponents>::New();
extractRedFilter->SetInputConnection(reader->GetOutputPort());
//0 1 2分别对应R G B
extractRedFilter->SetComponents(0);
extractRedFilter->Update();

auto colorTable = vtkSmartPointer<vtkLookupTable>::New();
//要映射的标量数据范围
colorTable->SetRange(0.0, 255.0);
//可以用SetTableValue指定特定颜色，也可以像下面一样指定范围
colorTable->SetHueRange(0.1, 0.5);
colorTable->SetValueRange(0.6, 1.0);
colorTable->Build();

auto colorMap = vtkSmartPointer<vtkImageMapToColors>::New();
colorMap->SetInputConnection(reader->GetOutputPort());
colorMap->SetLookupTable(colorTable);
colorMap->Update();

//就是融合三个灰度图，三个灰度值分别对应RGB
auto appendFilter = vtkSmartPointer<vtkImageAppendComponents>::New();
appendFilter->AddInputConnection(reader1->GetOutputPort());
appendFilter->AddInputConnection(reader2->GetOutputPort());
appendFilter->AddInputConnection(reader3->GetOutputPort());
appendFilter->Update();