ofxCvImage::rotate artifact

Hi,

I’m trying to get a clean rotation of an ofxCvImage. From 320x240 to 240x320. It’s important that the pixels are flipped as I’m going to be counting through them in a particular way.

I’ve noticed an artifact appears when rotating an ofxCvImage:

I also captured a video of a strange kaliedescopic effect that occurs when animating the rotation:

Is there a way to do a clean rotation (with say a black background) on an ofxCvImage?

Here’s the relevent snippet:

    grayDiff.threshold(threshold); // grayDiff the first ofxCvGrayscaleImage (320x240)
    rotDiff.setROI(0,0,320,240); // rotDiff is the second (320x320)
    rotDiff = grayDiff;
    rotDiff.resetROI();
    rotDiff.rotate(ofGetFrameNum(),160,160);

Thanks for any ideas!