EFFECTS OF ROLLING SHUTTER

Fashion|One will not accept clips with issues (enumerated below) caused by Rolling Shutter.

Wobble. This phenomenon (also known as the jello effect) is most common in hand-held shots at telephoto settings, and most extreme in cases when the camera is vibrating, possibly due to being attached to a moving vehicle, for instance. The rolling shutter causes the image to wobble unnaturally and bizarrely.

This picture is taken from: http://en.wikipedia.org/wiki/File:Jamtlands_Flyg_EC120B_Colibri.JPG

Skew. The image bends diagonally in one direction or another as the camera or subject moves from one side to another, exposing different parts of the image at different times. Essentially, skew is a very minor manifestation of the wobble phenomenon described above.

This picture is taken from: http://en.wikipedia.org/wiki/File:CMOS_rolling_shutter_distortion.jpg

Smear. This effect can be easily viewed with a cell phone camera and a fan/propeller. The smear of each blade is caused by the propeller rotating at the same or near the same speed that the frame is read by the camera. Viewed perpendicular to a fan spinning clockwise, the blades on the left side appear thinner than usual while the blades on the right side appear thicker and can even appear as if they aren't connected at the center.

This picture is taken from: http://en.wikipedia.org/wiki/File:Turboprop_Rolling_Shutter.jpg

Partial Exposure. If a camera flash goes off in the shot, the quick nature of the flash may only be present for some of the rows of pixels in a given frame. So as an example, the top 1/3 of the picture may be brightly lit by a flash, while the bottom 2/3 of the picture is dark and unlit as the time it took for the flash to occur was only sequenced in a short amount of time as the CMOS imager sequences a frame. The difference between the two distinct parts of the frame can look odd. Similar problems can arise with emergency vehicle lights, some fluorescent lighting, or any extreme situation where very fast motion or very fast bursts of light are seen in the time between when the CMOS chip sequentially records a frame.

Spatial and temporal aliasing. In signal processing and related disciplines, aliasing refers to an effect that causes different signals to become indistinguishable (or aliases of one another) when sampled. It also refers to the distortion or artifact that results when the signal reconstructed from samples is different from the original continuous signal.

Aliasing can occur in signals sampled in time, for instance digital audio, and is referred to as temporal aliasing. Aliasing can also occur in spatially sampled signals, for instance digital images. Aliasing in spatially sampled signals is called spatial aliasing.

Picture taken from: http://en.wikipedia.org/wiki/File:Moire_pattern_of_bricks_small.jpg

CCDs (charge-coupled devices) are alternatives to CMOS sensors . CCDs use what is referred to as global shutters which take a snapshot representing a single point of time and do not suffer from these motion artifacts.

The effects of a rolling shutter can prove difficult for visual effects filming. The process of match-moving establishes perspective in a scene based on a single point in time, however this is difficult with a rolling shutter that provides multiple points in time within the same frame. Final results depend on the readout speed of the sensor and the nature of the scene being filmed; as a rule of thumb, higher end cinema cameras will have faster readout speeds and therefore milder rolling shutter artifacts than low-end cameras.

*** Information about Rolling Shutter was taken from http://en.wikipedia.org/wiki/Rolling_shutter.