Editing Progressive scan (section)

== Interline twitter ==
{{Main|Interlaced video#Interline twitter}}
[[Image:Indian Head interlace.gif|thumb|right|200px|''Interline twitter'' when the refresh rate is slowed by a factor of three, demonstrated using the [[Indian-head test pattern]]]]
This rough animation compares progressive scan with [[Interlaced video|interlace]] scan, also demonstrating the [[interline twitter]] effect associated with interlacing. On the left there are two progressive scan images. In the middle there are two interlaced images and on the right there are two images with [[line doubler]]s. The original resolutions are above and the ones with [[spatial anti-aliasing]] are below. The interlaced images use half the bandwidth of the progressive ones. The images in the center column precisely duplicate the pixels of the ones on the left, but interlacing causes details to twitter. Real interlaced video blurs such details to prevent twittering, but as seen in the pictures of the lower row, such softening (or anti-aliasing) comes at the cost of image clarity. A line doubler shown in the bottom right picture cannot restore the previously interlaced image in the center to the full quality of the progressive image shown in the top left.

Note: Because the refresh rate has been slowed by a factor of three, and the resolution is less than half a resolution of a typical interlaced video, the flicker in the simulated interlaced portions and also the visibility of the black lines in these examples are exaggerated. Also, the images above are based on what it would look like on a monitor that does not support interlaced scan, such as a PC monitor or an LCD or plasma-based television set, with the interlaced images displayed using the same mode as the progressive images.