Object Transform

The Object Transform command applies a geometric transform to every object carrying Input class, keeping the object’s bounding-box centre fixed. Depending on the Output class, the transformed shape either replaces the input object in place or is added as a new, separate object alongside the untouched original.

Parameters

Parameter	Description
Function	The geometric transform to apply - see below
Input class	Objects carrying this class are the input to the transform
Output class	If unset (or equal to Input class), the transformed shape replaces the input object in place. If set, a new object carrying this class is created for each transformed object instead, leaving the input object untouched

Functions

Function	Description
Scale	Scales the object by a unitless factor. Shape is preserved; the object is only shrunk or expanded around its centre
Snap area	Draws a circle around the object’s bounding box, enlarged by Extra size (in the chosen Unit) on top of the bounding-box diameter
Min circle	Draws a circle around the object’s bounding box, using Min diameter as a lower bound - the circle never shrinks below the object’s own bounding box
Draw circle	Draws a circle with exactly Diameter as its diameter. If Diameter is 0, the object’s bounding box is used instead
Fitting ellipse	Replaces the object with the ellipse fitted to its mask, scaled by Scale (values ≤ 1.0 have no effect)
Expand	Grows the object outward by Margin (in the chosen Unit), following its actual contour uniformly. Unlike Scale, irregular shapes grow by a flat margin rather than proportionally
Shrink	Shrinks the object inward by Margin, following its actual contour. Objects that vanish after shrinking are removed

Snap area, Min circle, Draw circle, Expand, and Shrink express their size in a configurable Unit (e.g. px, nm, µm).

Behaviour Notes

• The transform keeps the object’s bounding-box centre fixed - only the shape and/or size change.
• A transformed shape that would extend past the image border is clipped, and the resulting object is flagged as touching the edge (same as any other object at the image boundary).
• Only objects carrying Input class are processed; objects without that class are left untouched.

Example: Approximating a cell area around each nucleus

Function:     Min circle
  Min diameter: 30
  Unit:         µm
Input class:  dapi@nucleus
Output class: cell@area

This creates a new cell@area object around every detected nucleus, at least 30 µm in diameter, without modifying the original nucleus objects - useful as a quick cell-area proxy when no cell-surface stain is available (compare with Voronoi for a partition-based alternative).