August 30, 2014

1 What is MatrixUser

2 Installing and Running MatrixUser

3 Data Import

4 Window Layout

5 Function Library

2 Installing and Running MatrixUser

3 Data Import

4 Window Layout

5 Function Library

Most of the medical images (e.g. CT, MRI, PET, etc.) comprises multiple frames which
represent slices, phases, timing etc. from the same imaging object. Those images can be saved as multidimensional matrices
in Matlab thanks to Matlab's powerful support of multidimensional data representation. However, within Matlab, most of image
manipulation functions are limited or tailored for processing two-dimensional matrix. The MatrixUser is a software package
which features functions designed and optimized specifically for manipulating multidimensional real or complex data matrix.
MatrixUser provides a nice graphical environment for easily performing image analysis tasks including multidimensional image
display, matrix (image stack) processing and rendering etc. MatrixUser is a great lightweight tool for users who are working
in image processing field under Matlab.

The current MatrixUser version (v2.2) is made available at SourceForge website.
MatrixUser is released as a free software. This means that you are free to use and
modify this software as your needs, as long as you acknowledge the original author in
any future work. If you find MatrixUser useful for the publication of any scientific
results, including a line in your acknowledgments section referencing to MatrixUser
and this belowing address is requested.

MatrixUser downloading address:

To run MatrixUser, a Matlab installment is required. The current MatrixUser version has been tested under the following Matlab versions:

- Matlab R2011a 64-bit Windows
- Matlab R2013a 64-bit Windows
- Matlab R2012b 64-bit Unix

Installing and running MatrixUser is easy, you just need to download MatrixUser
source code which is distributed as a compressed file, then extract the MatrixUser
root folder, put the folder to any location in you computer. To run MatrixUser, start
Matlab, then simply run the ‘Main.m’ script under the MatrixUser root folder.

The MatrixUser main window (Figure 1) works as a matrix manager.

Current MatrixUser version supports displaying any valid Matlab multi-dimensional matrix and Matlab structure variable. By default, MatrixUser reads Matlab base workspace, scans existing matrices in the Matlab session, then creates a matrix list for tracking matrix content. Once those matrices are updated by the user, MatrixUser will also update the matrix list. Moreover, there are several different approaches to import data from outside Matlab into MatrixUser. The imported matrices will be saved into Matlab base workspace. The import functions are located under ‘Load’ menu, including:

- Load MAT file
The default Matlab .mat file is natively supported by MatrixUser.

- Load System Clipboard
If image content exists in the system clipboard, it can be converted into a RGB image which contains a three slice matrix with each slice corresponds to the individual Red, Green and Blue channel.

- Load ScreenShot
MatrixUser takes a full screenshot for current monitor and saves it into a RGB image as described above.

- Load from Binary file
Binary data file is supported by MatrixUser. The user needs to properly configure loading parameters (Figure 2) according to the matrix size and data type information.

- Load DICOM file(s)
MatrixUser supports loading multiple DICOM files by using a file filter interface (Figure 3). The user needs to load DICOM files into the loading interface by selecting desired DICOM files (multiple selection supported). The selected files are listed in the DICOM file list. The user can click any single DICOM file to read associated DICOM header and image preview. To manually create a matrix using DICOM files, choose files from the DICOM file list, press ‘>>>>>>’ to push the files into selected DICOM file list, provide a matrix name, press ‘Convert’ button to create a matrix based on chosen DICOM files. The user can load those created matrices into base workspace by pressing ‘Load matrix’ button.

- Load DICOM file(s) in Batch
MatrixUser supports loading DICOM files in a batch mode. This function requires the path of the folder containing DICOM files is provided. MatrixUser will try to create separate matrices for DICOM files coming from different image series. A matrix selection interface will provide converted matrices with loading functions.

- Load from NIfTI file
NIfTI file with .nii suffix is supported by MatrixUser.

To activate MatrixUser display window, press ‘MatrixUser’ button. If the selected matrix contains complex value, four options are available for displaying magnitude, phase, real and imaginary of the matrix. Figure 4 demonstrates an overview of the window layout of the MatrixUser display window. The window consists of

- Matlab Default Toolbar

Matlab toolbar provides basic interactive functions for displaying matrix. These functions include:

- : Save current image axes into an image file
- : Zoom in matrix area
- : Zoom out matrix area
- : Manually move matrix position
- : Check individual voxel value and index
- : Print current figure
- : Turn on/off color bar

- MatrixUser Function Library

Most of the matrix analysis functions are represented on function bench panel. MatrixUser groups these functions into categories and dynamically loads them according to the dimension size and compatibility of current display matrix. A multi-tab is used to contain individual function button associated with each function. The tabs under the multi-tab are used to switch between function categories, which include

- Display : Multi-dimensional matrix display functions
- QuickMath : Perform math calculation for current matrix
- Transform : Transform current matrix
- Process : Basic matrix processing functions
- ROI : Region-of-Interest functions
- Segment : Segmentation functions
- Surface : Generate surface or mesh plot for current image
- Matlab : Matlab default image tools
- More : Uncategorized functions

- Matrix Calculator

The matrix calculator consists of three control items, including a matrix expression editbox, an execution button ( ) and a matrix saving button ( ). Valid matrix calculation expression can be executed in the calculator and updated in the display window, serving as a convenient way to analyze matrix calculation result. Matrix concatenation and recombination can also be done in the calculator, for example, to side-by-side compare multiple 3D matrices (Figure 5). Some valid calculation examples are, but not limited to:

- A,B Combines A and B in one row
- A,B;C,D Combines A and B in the first row, C and D in the second row
- A,B;C,zeros(size(C)) Combines A and B in the first row, C in the second row, pad with zero value
- sin(A),cos(B) Calculates voxel-wise sin for A and cos for B, then combine them in one row
- A(:,1:10,:) Extracts submatrix from A and display it

where A, B, C and D are multi-dimensional matrices with proper matrix size. Also note that the source matrices have to stay in the base workspace for being referenced. Pressing the execution button will perform the calculation and save the result as a temporary matrix. The user can also save the temporary matrix into workspace by pressing matrix saving button. The saved temporary matrix will have a ‘_tmp’ suffix by default.

- Matrix Display Axes

The display axes renders an image for one slice of current matrix. The user can use mouse cursor to inspect the coordinate and value of any voxel. Moving mouse wheel back and forth moves the slice location along current dimension and updates the display axes.

- Matrix Color Control Group

The matrix color control group provides a set of sliders, editboxes and popup menu which help control image color scheme and contrast. This group consists of

- Colormap Popup Menu: Choose different colormap scheme
- Upper Color Bound Slider (right slider): Slide to control the upper bound of color limits
- Upper Color Bound EditText (right editbox): Edit to control the upper bound of color limits
- Lower Color Bound Slider (left slider): Slide to control the lower bound of color limits
- Lower Color Bound EditText (left editbox): Edit to control the lower bound of color limits

- Matrix Dimension Control Group

MatrixUser measures the dimension size of the display matrix and assigns one slider and editbox for each dimension that is above 2 (i.e. no slider and editbox for the first and second dimension). These control items are located in individual dimension tab and can be used to switch among slices in current active dimension.

- Display

Matrix display functions are listed under this tab.

- : Reset matrix display and erase additional display effect
- : Turn on and off black grid line on the image display axes
- : Configure axis mode
- : Open an instant magnifier which zooms in specific image area
- : Plot and update a profile curve along a resizable checking
line (Figure 6)

- : Plot and update a profile curve along a matrix dimension (Figure
7)

- : Open a separate window with two matrix display axes (Figure 8)
displaying another two orthogonal images. The operation buttons on the
second window consists of
- : Activate or deactivate localizer line on main display
- : Activate or deactivate localizer line on main display
- : Switch matrices between main display and second display. This operation simply permutes current matrix into its orthogonal version. The user can save the transformed matrix using ( ).

- : Create a RGB Image, assign current slice and following two slices to Red, Green and Blue channel, respectively
- : Create a montage image using multiple slices (Figure
9)

- : Overlap two matrices with the same matrix size (Figure 10),
notice that the user can press to remove foreground matrix from
overlapping with background matrix.

- QuickMath

This function category performs quick math calculation for current matrix. A few commonly used math calculation are provided under this tab. Instead, complex calculation can be performed using matrix calculator as mentioned above.

- : Calculate absolute value
- : Calculate negative value
- : Calculate natural logarithm
- : Calculate base 10 logarithm
- : Calculate exponential
- : Calculate the power of 10
- : Calculate sine
- : Calculate cosine
- : Calculate tangent
- : Calculate inverse sine
- : Calculate inverse cosine
- : Calculate inverse tangent

- Transform

This function category performs spatial transformation or fast Fourier transform (FFT) to current matrix.

- : Flip matrix horizontally (along the first dimension)
- : Flip matrix vertically (along the second dimension)
- : Flip matrix along slice direction (the third dimension)
- : Rotate matrix 90 degree in the counter clockwise direction
- : Rotate matrix 90 degree in the clockwise direction
- : Rotate matrix certain degree along an axis specified using the rotation axis origin and direction in the 3D space
- : Translate matrix along certain direction
- : Perform multi-dimensional FFT for current matrix, the user needs to specify up to which dimension to perform FFT.

- Process

This function category performs basic matrix processing functions.

- : Create binary mask according to given threshold
- : Perform smoothing operation to current matrix
- : Perform sharpening operation to current matrix
- : Perform edge detection to current matrix
- : Provides various image filters (Figure 11)

- : Add noise to matrix (Figure 12)

- : Replace voxel value for the voxels within certain value range and outside a polygon area. The user needs to draw a polygon first (double click to confirm the polygon).
- : Replace voxel value for the voxels within certain value range and inside a polygon area. The user needs to draw a polygon first (double click to confirm the polygon).
- : Replace voxel value for the voxels inside a polygon area. The user needs to draw a polygon first (double click to confirm the polygon).
- : Replace matrix area with a selected matrix source region. The user needs to draw a free-hand area (source region), drag the free-hand region to target matrix area, then double click to confirm the operation.
- : Crop current matrix using a rectangle box (double click to confirm the cropping)
- : Extract parts of current matrix using irregular shape (double click to confirm the extracting)
- : Resample current matrix by using chosen interpolation method
(Figure 13). The user can specify sampling factors in x, y and z direction
for 3D matrix.

- ROI

MatrixUser provides a set of function buttons for performing Region-of-Interest (ROI) analysis (Figure 14). To create a ROI, the user needs to click ROI button first, then draw a ROI on the image axes. The statistical measures (i.e. mean, standard deviation and relative standard deviation) for voxels in delineated ROI is calculated and updated with moving ROI position or changing ROI shape. The ROI function buttons consists of

- : Draw a free hand ROI
- : Draw a rectangle or square ROI
- : Draw a circle or ellipse ROI
- : Draw a polygon ROI
- : Draw a straight line for measuring distance in units of pixels
- : Draw a polygon for measuring the interior angles in degrees
- : Record existing ROI shape and location into a ROI list, allow to redraw selected ROI in multiple image axes. To redraw a existing ROI, the user needs to select a ROI in the list, then press ‘Show’ button. Note that the copied ROI is no longer resizable and movable.
- : Plot histogram for current slice (Figure 15); if ROIs exist, plot histogram for latest activated ROI. Histogram can be fitted by using multiple distribution types. For more complex fitting, Matlab built-in FitTool can be used.

- Segment

MatrixUser supports functions for performing multi-slice manual segmentation. To create a segmentation, click segmentation button, then draw a region on the image axes. The user can modify the region location and shape prior to confirming segmentation with double click. The segmentation buttons consists of

- : Do a free-hand segmentation
- : Do a circle or ellipse segmentation
- : Do a polygon segmentation
- : Edit segmentation
- : Save segmentation into a MAT file
- : Load segmentation from a MAT file

To edit segmented region (Figure 16), press to open a segmentation manager. The manager records the type and location for existing segmented regions. The user can click any region item to inspect the location of the region. To edit chosen region, click ‘Edit’ button to activate the region outline. Both the shape and mask flag are editable for segmented region. After editing, click ‘Update’ to conform modification. The user can press to save current segmentation into a MAT file which contains a mask matrix and a cell array storing segmentation location information. The user can also press to save the mask matrix into workspace. Pressing can load previous segmented regions from a saved MAT file. Notice that the user can press to remove segmentation from overlapping with background matrix.

- Surface

This function category generates surface or mesh plot for current image.

- : Create contour plot of current matrix
- : Create 3D contour plot of current matrix
- : Create filled 2D contour plot
- : Create 3D shaded surface plot
- : Create surface plot and contour
- : Create surface plot with colormap based lighting
- : Create mesh plot
- : Create mesh plot and contour
- : Create a curtain around a mesh plot
- : Create a ribbon plot
- : Create a waterfall plot
- : Create pcolor (checkerboard) plot

- Matlab

Matlab default image tools (Figure 17) are tailored for MatrixUser and included in this category.

- : Perform imtool for current image
- : Perform immovie for playback current 3D matrix
- : Perform imcontrast for adjusting image contrast

- More

Uncategorized functions are categorized under this tab.

- : Create a 3D graph for rendering current matrix (Figure 18)

- : Perform projection along a given matrix dimension. Support multi-dimensional matrix projection
- : Perform 3D projection along x, y or z axis with certain angle
increment (Figure 19)

- : Reslice 3D matrix at given direction. The user needs to draw a line for indicating the slicing direction with double click for confirmation (Figure 20)
- : Create a movie using current matrix display. Support making movie for overlapped matrices.

- : Create a 3D graph for rendering current matrix (Figure 18)