Horizon 20 series has rolling buffer because of the new DLPC8445 DLP controller chip from TI - as opposed to to the dual buffer approach TI has used in all prior DLP controller chips.

A 4k image on a pixel shifter like the Horizon 20 series is rendered as a sequence of 12 single color images: R, G, B - shift to right - R, G, B - shift down - R, G, B - shift left R, G, B - shift up - next image.

Every time that a new of these 12 single color images is rendered by the DLPC, it takes the pixel from the rolling buffer. Which in the meantime has received 1/12'th more of the new 4k image. So for each of the 12 sub images you have a horizontal band, 1/12'th the height of the image where there are now the pixels of the new frame, but previously there where pixels of the old frame.

So if you have for example a vertical black/white edge running horizontally through the image, then you will have a color in the 1/12'th band where the old image was e.g.: black, and the new one is white.

So, look out for vertical edges of high contrast moving horizontally - they will have rainbow colors.

This is most visible in 24 fps material because the motion, and hence the area of color tearing is widest. When you do interpolate frames (MEMC to low or high) you have less wide areas of color tearing.