ImageDev

VolumeProjection3d

Creates a single image containing selected pixels from a volume image.

Access to parameter description

VolumeProjection3d flattens a 3D volume into an image with only two representative dimensions.

Each output pixel is assigned by browsing a selected axis and retaining the value corresponding to a projection criterion; for example, the maximal intensity.

The output image can be considered either as a 2D image or a 3D image.
Choosing a 3D output space is almost relevant for raising ambiguity when the selected axis is not Z and the result has to be displayed in a 3D viewer.
For instance, considering that the projection is performed along X: An optional output can be enabled to get a map representing the slice index of each selected pixel.
This map is not available in mean projection mode since, in this case, the output value is computed from all browsed intensities.

<b> (a) </b>
(a)
<b> (b) </b>
(b)
<b> (c) </b>
(c)
Figure 1. Mean Intensity projection: (a) The input volume,
(b) the mean projection along the Z axis, (c) mean projection along the Y axis

This algorithm is similar to ImageStackProjection3d, the main differences are:
See also

Function Syntax

This function returns a VolumeProjection3dOutput structure containing outputImage and outputMapImage. 
// Output structure of the volumeProjection3d function.
struct VolumeProjection3dOutput
{
    /// The output image representing the volume projection according to the selected criterion.
    std::shared_ptr< iolink::ImageView > outputImage;
    /// Output image indicating the selected plane in INTENSITY_MINIMUM or INTENSITY_MAXIMUM mode (not available in INTENSITY_MEAN mode).
    std::shared_ptr< iolink::ImageView > outputMapImage;
};

// Function prototype
VolumeProjection3dOutput
volumeProjection3d( std::shared_ptr< iolink::ImageView > inputImage,
                    VolumeProjection3d::AxisDirection axisDirection,
                    VolumeProjection3d::ProjectionMode projectionMode,
                    VolumeProjection3d::DimensionalSpace dimensionalSpace,
                    bool createMapImage,
                    std::shared_ptr< iolink::ImageView > outputImage = NULL,
                    std::shared_ptr< iolink::ImageView > outputMapImage = NULL );

Class Syntax

Parameters

Parameter Name Description Type Supported Values Default Value
input
inputImage
The 3D input image.
Color and grayscale images are accepted. The type of the image can be integer or float. 		Image Grayscale or Multispectral nullptr
input
axisDirection
The axis along which slices are projected.
If axis direction is set to X, YZ slices are projected.
X_AXIS The YZ slices are projected.
Y_AXIS The XZ slices are projected.
Z_AXIS The XY slices are projected.
Enumeration Z_AXIS
input
projectionMode
The projection criterion (the rule used to transform a stack of pixels into a single pixel).
INTENSITY_MAXIMA The pixel of highest intensity is selected in the stack. The map output is available with this mode.
INTENSITY_MINIMA The pixel of lowest intensity is selected in the stack. The map output is available with this mode.
INTENSITY_MEAN The pixels of the stack are averaged along the selected axis. The map output is not available with this mode.
Enumeration INTENSITY_MEAN
input
dimensionalSpace
Define the dimensional space of the output image.
If axis direction is set to X and space to 2D, the output X (resp. Y) axis corresponds to the Y (resp. Z) axis. If axis direction is set to X and space to 3D, the output X axis is one pixel thick.
SPACE_2D The output image is a 2D image.
SPACE_3D The output image is a 3D image.
Enumeration SPACE_2D
input
createMapImage
This parameter indicates whether the algorithm creates an output map image.
This parameter is ignored in INTENSITY_MEAN projection mode. 		Bool false
output
outputImage
The output image representing the volume projection according to the selected criterion.
This image can be either 2D or 3D of one pixel thickness in the selected axis direction. Its type is identical to the input image. 		Image nullptr
output
outputMapImage
Output image indicating the selected plane in INTENSITY_MINIMUM or INTENSITY_MAXIMUM mode (not available in INTENSITY_MEAN mode).
The output map image can be either 2D or 3D of one pixel thickness in the selected axis direction. Its type is integer 32 bits. 		Image nullptr

Object Examples

auto foam = readVipImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "foam.vip" );

VolumeProjection3d volumeProjection3dAlgo;
volumeProjection3dAlgo.setInputImage( foam );
volumeProjection3dAlgo.setAxisDirection( VolumeProjection3d::AxisDirection::Z_AXIS );
volumeProjection3dAlgo.setProjectionMode( VolumeProjection3d::ProjectionMode::INTENSITY_MEAN );
volumeProjection3dAlgo.setDimensionalSpace( VolumeProjection3d::DimensionalSpace::SPACE_2D );
volumeProjection3dAlgo.setCreateMapImage( false );
volumeProjection3dAlgo.execute();

std::cout << "outputImage:" << volumeProjection3dAlgo.outputImage()->toString();
std::cout << "outputMapImage:" << volumeProjection3dAlgo.outputMapImage()->toString();

Function Examples

auto foam = readVipImage( std::string( IMAGEDEVDATA_IMAGES_FOLDER ) + "foam.vip" );

auto result = volumeProjection3d( foam, VolumeProjection3d::AxisDirection::Z_AXIS, VolumeProjection3d::ProjectionMode::INTENSITY_MEAN, VolumeProjection3d::DimensionalSpace::SPACE_2D, false );

std::cout << "outputImage:" << result.outputImage->toString();
std::cout << "outputMapImage:" << result.outputMapImage->toString();