What frame of reference does OME uses to map ROI to a picture?

In OMERO, ROIs are defined by one or more Shapes (e.g. Rectangle, Ellipse), allowing an ROI to span multiple Z and T sections.

The position of a Shape on an image plane is given by x and y coordinates from the top left of the image.

Different shapes, listed here are measured differently:

e.g.

• Rectangle has x and y to define the location of the top, left of a rectangle,

whereas

• Ellipse has cx and cy to denote the x, y coordinates of the ellipse center.