OriginX
Horizontal unit coordinate of the origin with respect to left edge. Permitted values in [0, 1]. A value of 0.0 means the origin lies on the left edge, 0.5 means the origin lies in the middle and 1.0 means the origin is on the right edge.
OriginY
Vertical unit coordinate of the origin with respect to top edge. Permitted values in [0, 1]. A value of 0.0 means the origin lies on the top edge, 0.5 means the origin lies in the middle and 1.0 means the origin is on the bottom edge.
https://ai2.appinventor.mit.edu/reference/components/animation.html#ImageSprite