VoxelValueRescale

MLModule

genre	Scale
status	stable
author	Tobias Boskamp
package	MeVisLab/Standard
dll	MLMiscModules
definition	MLMiscModules.def
see also	DicomTagViewer, DicomTagModify, Scale, DicomLUT
keywords	Voxel, Value, LUT, Lookup, table, Rescale, Intercept, Slope, Center, Width, Hounsfield, Unit, Gray, CT, Dicom

Purpose

The module VoxelValueRescale converts image voxel values, image range or LUT window center and width values between their stored representation (as found in the DICOM file) and their output representation (machine independent, e.g. Hounsfield units).

Usage

If an image is connected to the image input field, the transformation parameters Intercept and Slope are read from the image's DICOM tags Rescale Intercept and Rescale Slope, and the image value range is taken from the image properties.

If no image is connected, the transformation parameters and image range values can be set manually.

Conversion takes place between the stored and the output voxel, LUT center and LUT width values in both directions. The image range values are only converted from stored to output representation.

Details

The transformation between stored and output values is based on the linear mapping

output = stored * slope + intercept

This transformation is often used for CT images, where pixel values typically are stored with an offset of 1024 in order to obtain non-negative image data values.

The above transformation (with slope = 1 and intercept = -1024 for typical CT images) converts the stored pixel values to Hounsfield units, which start from -1024.

Windows

Default Panel

Input Fields

input0

name: input0, type: Image

Parameter Fields

Field Index

Image Max (storedMax): Double	LUT Center (outputCenter): Double
Image Max (outputMax): Double	LUT Width (storedWidth): Double
Image Min (storedMin): Double	LUT Width (outputWidth): Double
Image Min (outputMin): Double	outputRangeNeg: Double
Image Range (storedRange): Double	Slope: Double
Image Range (outputRange): Double	storedRangeNeg: Double
Intercept: Double	Voxel Value (storedValue): Double
LUT Center (storedCenter): Double	Voxel Value (outputValue): Double

Visible Fields

Slope

name: slope, type: Double, default: 1

Shows and sets the slope value.

Intercept

name: intercept, type: Double, default: 0

Shows and sets the intercept value.

Image Min (storedMin)

name: storedMin, type: Double, default: 0

Shows and set the stored minimum value.

Image Max (storedMax)

name: storedMax, type: Double, default: 1

Shows and set the stored maximum value.

Image Range (storedRange)

name: storedRange, type: Double, persistent: no

Shows the stored image value range.

Voxel Value (storedValue)

name: storedValue, type: Double, default: 0, minimum: :field:`storedMin`, maximum: :field:`storedMax`

Shows and sets one voxel value.

This voxel value is converted.

LUT Center (storedCenter)

name: storedCenter, type: Double, default: 0.5, minimum: :field:`storedMin`, maximum: :field:`storedMax`

Shows and sets the LUT center for the stored values.

LUT Width (storedWidth)

name: storedWidth, type: Double, default: 1, minimum: :field:`storedRangeNeg`, maximum: :field:`storedRange`

Shows and sets the LUT width for the stored values.

Image Min (outputMin)

name: outputMin, type: Double, persistent: no

Shows the minimum image value after conversion.

Image Max (outputMax)

name: outputMax, type: Double, persistent: no

Shows the maximum image value after conversion.

Image Range (outputRange)

name: outputRange, type: Double, persistent: no

Shows the image value range in the converted image.

Voxel Value (outputValue)

name: outputValue, type: Double, default: 0.5, minimum: :field:`outputMin`, maximum: :field:`outputMax`

Shows and sets a voxel value after the conversion.

LUT Center (outputCenter)

name: outputCenter, type: Double, default: 1, minimum: :field:`outputMin`, maximum: :field:`outputMax`

Shows and sets the LUT center after the conversion.

LUT Width (outputWidth)

name: outputWidth, type: Double, default: 1, minimum: :field:`outputRangeNeg`, maximum: :field:`outputRange`

Shows and sets the LUT width after the conversion.

Hidden Fields

storedRangeNeg

name: storedRangeNeg, type: Double, default: -1

outputRangeNeg

name: outputRangeNeg, type: Double, default: -1