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Flip

The Flip tool mirrors volume and mask data along one or more axes. Flipping is useful for correcting orientation issues or creating mirrored versions of datasets.

Flip vs Swap Axes​

Flip and Swap Axes are related, but they do different things:

  • Flip mirrors the data along X, Y, or Z.
  • Swap Axes changes which physical direction is treated as X, Y, or Z.
  • Use Flip when the axis direction is inverted.
  • Use Swap Axes when two axes are in the wrong order.

In short: Flip creates a mirrored result while keeping the same axis order, whereas Swap Axes reorders the axes themselves.

A shape on X and Y axes, the same shape mirrored along X by Flip, and the same shape with X and Y exchanged by Swap Axes

Accessing the Tool​

  1. Navigate to the Image tab in the ribbon.
  2. Click Flip in the Transform section.

Parameters​

Flip Axes​

Select the axes along which to flip the data. The X, Y, and Z check boxes are independent, so you can combine them and apply the result in a single step.

AxisEffect
XMirrors across the YZ plane (Plane 1)
YMirrors across the XZ plane (Plane 2)
ZMirrors across the XY plane (Plane 3)

Selecting more than one axis mirrors along each selected axis in a single operation. For example, selecting X and Y gives the same result as flipping along X and then flipping along Y. At least one axis must be selected before applying.

Flip Reference​

Choose the reference point for the flip operation:

OptionDescription
About originFlip using the coordinate system origin (0, 0, 0) as the mirror plane
About centerFlip using the object's geometric center as the mirror plane

Visual Effect​

Flipping creates a mirror image:

  • X-axis flip: Left becomes right, right becomes left
  • Y-axis flip: Front becomes back, back becomes front
  • Z-axis flip: Top becomes bottom, bottom becomes top

Selecting several axes applies each of these effects at the same time.

Workflow​

  1. Open the Flip tool from the Image tab.
  2. Select one or more axes to flip along (X, Y, Z).
  3. Choose the flip reference (About origin or About center).
  4. Click Apply to flip the data.

Use Cases​

Correcting Import Orientation​

Some data sources may have inverted axes:

  1. Identify which axes are inverted by comparing to known anatomy.
  2. Select those axes and apply the flip to correct the orientation.
  3. Verify the result in orthogonal slice views.

Creating Mirrored Datasets​

For bilateral symmetry analysis:

  1. Flip a left-side dataset to create a right-side version.
  2. Compare or overlay with actual right-side data.
  3. Useful for symmetry studies and contralateral comparison.

Matching Coordinate Conventions​

Different software may use different coordinate conventions:

  • Right-handed vs. left-handed coordinate systems
  • Different axis definitions (RAS, LPS, etc.)
  • Flip as needed to match target conventions

If the issue is an exchanged axis order rather than an inverted direction, use Swap Axes instead.

Affected Objects​

Flipping affects:

  • All volume objects
  • All mask objects

Both are flipped together to maintain spatial correspondence.

warning

Flipping may cause DICOM orientation metadata to become incorrect. Verify patient orientation labels after flipping medical datasets.

Medical Imaging Considerations​

danger

In medical imaging, incorrect left-right orientation can have serious consequences. Always verify anatomical landmarks after flipping to ensure correct patient orientation.

Standard medical imaging conventions:

  • R = Patient's Right
  • L = Patient's Left
  • A = Anterior (front)
  • P = Posterior (back)
  • S = Superior (head)
  • I = Inferior (feet)

Scripting​

This operation is available via the Python scripting API using flip().

import ScriptingApi as api

app = api.Application()
volume_operations = app.get_volume_operations()

# Flip along X axis about the origin
volume_operations.flip(
    ["Volume1"],
    True,   # flip_x
    False,  # flip_y
    False,  # flip_z
    True    # about_origin: True=origin, False=center
)

# Flip along Z axis about the center
volume_operations.flip(["Volume1"], False, False, True, False)

# Flip along the X and Y axes in one call
volume_operations.flip(["Volume1"], True, True, False, True)

At least one axis must be selected, otherwise the call raises an error.

See the VolumeOperations API Reference for details.

See also: Swap Axes