Unwanted 'Pulsing' when Changing an Image's Angle

[Ray]

Greetings,

I've got an image of a beach ball, about 100 pixels in both width and 
height.  If I use a repeat loop to cycle through setting the angle of 
the image from a value of 360 down to 0 it spins, as intended, but it 
also 'pulses' toward me and away from me, twelve times I believe for 
each 360 degrees.

It seems like for the first 15 degrees of change the image gets 
smaller.  Then for the next 15 degrees it gets bigger again and repeats 
this.  There's no change in the bounding rectangle.

Does anybody know the math formula or any other way to compensate for 
this so I can eliminate the unwanted pulsing?

Many thanks!

Ray Horsley
LinkIt! Software