sliceViewer

Browse image slices

Description

A sliceViewer object displays individual slices of grayscale and RGB volumes. You can control which slice to display by using a slider.

When it opens, the sliceViewer object displays the middle image in the stack in the direction specified by sliceDirection. Use the slider to navigate through the volume and view individual slices.

The sliceViewer object supports properties, object functions, and events that you can use to customize its appearance and functioning. The sliceViewer object can send notifications when certain events occur, such as the slider moving. For more information, see Events.

Note

By default, clicking and dragging the mouse in the slice displayed interactively changes their brightness and contrast, a technique called window/level. Dragging the mouse horizontally from left to right changes the contrast. Dragging the mouse vertically up and down changes the brightness. Holding down the Ctrl key when clicking and dragging the mouse accelerates changes. Holding down the Shift key while clicking and dragging the mouse slows the rate of change. Press these keys before clicking and dragging. To control this behavior, use the DisplayRangeInteraction property.

Creation

Description

sliceViewer(V) displays the grayscale or RGB volume V in a figure. The figure includes a slider that you can use to view individual slices of the volume.

sliceViewer(___,Name,Value) sets properties using name-value pair arguments. You can specify multiple name-value pairs. Enclose each property name in single quotes.

Example: sliceViewer(V,'Colormap',cmap) creates a sliceViewer object and specifies the colormap used to display the volume.

sv = sliceViewer(___) returns a sliceViewer object, sv, with properties that can be used to control visualization of the volume. Use input arguments from any of the previous syntaxes.

Note

Medical Imaging Toolbox™ extends the functionality of the sliceViewer (Image Processing Toolbox™) object to display the slices of a medicalVolume (Medical Imaging Toolbox) object. For more information, see sliceViewer (Medical Imaging Toolbox).

Input Arguments

V — Input volume

m-by-n-by-p-by-c numeric array

Input volume, specified as an m-by-n-by-p-by-c numeric array. For grayscale volumes, c is 1. For RGB volumes, c is 3. RGB volumes can only be of class uint8, uint16, single, and double.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32

Properties

Colormap — Colormap of image stack

gray(256) (default) | m-by-3 numeric array

Colormap of the image stack, specified as an m-by-3 numeric array with values in the range [0 1]. The Colormap property has no effect when V is an RGB image stack.

DisplayRange — Display range of image stack

[min(V(:)) max(V(:))] (default) | two-element vector

Display range of image stack, specified as a two-element vector of the form [low high]. The value low (and any value less than low) displays as black. The value high (and any value greater than high) displays as white. Values in between are displayed as intermediate shades of gray, using the default number of gray levels. If you specify an empty matrix ([]), sliceViewer uses the default value. DisplayRange has no effect when you specify a stack of RGB images.

DisplayRangeInteraction — Enable interactive control of display range

'on' | 'off'

Enable interactive control of display range, specified as one of these values. To learn more about interactive behavior, see Events.

Value	Description
'on' (default for grayscale intensity volumes)	Control the display range of a grayscale image stack by left-clicking the mouse and dragging it on the axes.
'off' (default for logical and RGB volumes)	No display range interactivity.

Parent — Parent of sliceViewer object

gcf (default) | uipanel | figure

Parent of the sliceViewer object, specified as a handle to a uipanel or a figure created with the figure or uifigure commands. If you do not specify a parent, the parent of the sliceViewer object is gcf.

ScaleFactors — Scale factors used to rescale the volume

[1 1 1] (default) | 1-by-3 positive numeric vector

Scale factors used to rescale the volume, specified as a 1-by-3 positive numeric vector. The values in the array correspond to the scale factor applied in the x, y, and z directions.

SliceDirection — Direction in which to browse image stack

[0 0 1] (default) | 1-by-3 logical vector | 'X' | 'Y' | 'Z'

Direction in which to browse image stack, specified as 1-by-3 logical vector or one of the character vectors in this table.

Character Vector	Logical Vector	Description
'X'	[1 0 0]	Browse in X direction
'Y'	[0 1 0]	Browse in Y direction
'Z' (default)	[0 0 1]	Browse in Z direction

SliceNumber — Index of slice to be displayed

center slice | positive numeric scalar

Index of the slice to be displayed from the volume, specified as a positive numeric scalar.

Object Functions

addlistener	Create event listener bound to event source
getAxesHandle	Get handle to axes in Slice Viewer

Examples

View MRI Data in Slice Viewer

Load MRI data into the workspace.

load mristack

View the data in the slice viewer, specifying a custom colormap for viewing the slices. The slice viewer opens the stack of images and displays the one in the middle. Use the slider to view a different slice.

cmap = parula(256);
s = sliceViewer(mristack,"Colormap",cmap,"Parent",figure);

Create GIF of Slices Using the Slice Viewer

Load MRI data into the workspace.

load mristack

View the data in the slice viewer.

s = sliceViewer(mristack,"Parent",figure);

Get the handle of the axes containing the displayed slice.

hAx = getAxesHandle(s);

Specify the name of the GIF file you want to create.

filename = "animatedSlice.gif";

Create an array of slice numbers.

sliceNums = 1:21;

Loop through the slice numbers and create an image of each displayed slice. Write the images to a GIF file.

for idx = sliceNums
    % Update slice number
    s.SliceNumber = idx;
    % Use getframe to capture image
    I = getframe(hAx);
    [indI,cm] = rgb2ind(I.cdata,256);
    % Write frame to the GIF file
    if idx == 1
        imwrite(indI,cm,filename,"gif","Loopcount",inf,"DelayTime", 0.05);
    else
        imwrite(indI,cm,filename,"gif","WriteMode","append","DelayTime", 0.05);
    end
end

Set Up Listener for Slice Viewer Slider Events

Load a stack of images into the workspace.

load mristack

View the data in the slice viewer, specifying a custom colormap for viewing the slices. The slice viewer opens the stack of images and displays the one in the middle. Use the slider to view a different slice.

cmap = parula(256);
s = sliceViewer(mristack,"Colormap",cmap,"Parent",figure);

Set up listeners for the two sliceViewer object slider events: when the slider is moving and when the slider has been moved. When you move the slider, the slice viewer sends notifications of these events and executes the specified callback function.

addlistener(s,"SliderValueChanging",@allevents);
addlistener(s,"SliderValueChanged",@allevents);

Use this allevents callback function to display the name of each event and the current position of the slider.

function allevents(src,evt)
    evname = evt.EventName;
    switch(evname)
        case{"SliderValueChanging"}
            disp("Slider value changing event: " + mat2str(evt.CurrentValue));
        case{"SliderValueChanged"}
            disp("Slider value changed event: " + mat2str(evt.CurrentValue));
    end
end

More About

Events

The sliceViewer object can send notifications when the slider moves. To receive these notifications, use the addListener object function to set up a listener. To set up a listener, specify the name of the event, for example, 'SliderValueChanging', and the function you want executed when the event occurs. The following table lists events supported by the sliceViewer object. For an example, see Set Up Listener for Slice Viewer Slider Events.

Event Name	Trigger	Event Data	Event Attributes
SliderValueChanging	The slider in the sliceViewer object is moving.	images.stack.browser.SliderMovingEventData	NotifyAccess: private ListenAccess: public
SliderValueChanged	The slider in the sliceViewer object has been moved.	images.stack.browser.SliderMovingEventData	NotifyAccess: private ListenAccess: public

Version History

Introduced in R2019b