This article is about the image capture method. For the type of window shutter, see Roller shutter.
Animation showing the rolling shutter effectA de Havilland Canada Dash 8 Q-400 six-blade propeller, with severe rolling-shutter distortion from a Pixel 3 cameraA Eurocopter EC-120 helicopter – the rotor blades seem to be swept back more than usual due to the rolling-shutter effect.Simulation of the rolling-shutter effect on a rotating propeller and a moving car (click for SMIL animation)
Rolling shutter is a method of image capture in which a still picture (in a still camera) or each frame of a video (in a video camera) is captured not by taking a snapshot of the entire scene at a single instant in time but rather by scanning across the scene rapidly, vertically, horizontally or rotationally. In other words, not all parts of the image of the scene are recorded at exactly the same instant. (Though, during playback, the entire image of the scene is displayed at once, as if it represents a single instant in time.) This produces predictable distortions of fast-moving objects or rapid flashes of light. This is in contrast with "global shutter" in which the entire frame is captured at the same instant.
The rolling shutter can be either mechanical or electronic.[1][2] The advantage of this electronic rolling shutter is that the image sensor can continue to gather photons during the acquisition process, thus effectively increasing sensitivity. It is found on many digital still and video cameras using CMOS sensors. The effect is most noticeable when imaging extreme conditions of motion or the fast flashing of light. While some CMOS sensors use a global shutter,[3] the majority found in the consumer market use a rolling shutter.
CCDs (charge-coupled devices) are alternatives to CMOS sensors, which are generally more sensitive and more expensive.[citation needed] CCD-based cameras often use global shutters, which take a snapshot representing a “relative” single instant in time and therefore do not suffer from the motion artifacts caused by rolling shutters.[4]
Wobble. This phenomenon (also known as the jello effect) appears when the camera is vibrating, in situations such as hand-held shots at telephoto settings, or when shooting from a moving vehicle. The rolling shutter causes the image to wobble unnaturally.
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. Skew is a minor manifestation of the wobble phenomenon described above.
Spatial aliasing. Vertically adjacent pixels are sampled in violation of the sampling theorem, when the camera or object motion is too rapid. One example of this is imaging of a quickly rotating 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.
Temporal aliasing, including partial exposure. If a camera flash goes on for only part of the time of the exposure, the illumination of the flash may only be present for some rows of pixels in a given frame. For 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 flash was off by the time that part of the CMOS was sequenced. The difference between the two distinct parts of the frame can look odd. Similar problems can arise with fluorescent lighting, strobe effects, lightning, 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.
The effects of a rolling shutter can prove difficult for visual effects filming. The process of matchmoving establishes perspective in a scene based on a single point in time, but 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.
Images and video that suffer from rolling shutter distortion can be improved by algorithms that do rolling shutter rectification, or rolling shutter compensation. How to do this is an active area of research.[5]
This effect can be used to gain secret keys from certain smart card readers.[6][7]
Distortion examples
A photo exhibiting partial exposure. Lighting conditions changed between the exposure of the top and bottom parts of the photo.
Skewing in a photograph taken from a car moving at 80km/h (50mph). Objects in the foreground, such as the fence and gate, have become skewed, while more distant objects in the background, such as the cliff, remain as normal.
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging.
A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system that permits the photographer to view through the lens and see exactly what will be captured. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image. When the shutter button is pressed on most SLRs, the mirror flips out of the light path, allowing light to pass through to the light receptor and the image to be captured.
A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of the camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century.
A digital camera, also called a digicam, is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile devices like smartphones with the same or more capabilities and features of dedicated cameras. High-end, high-definition dedicated cameras are still commonly used by professionals and those who desire to take higher-quality photographs.
In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. 1⁄500 of a second will let half as much light in as 1⁄250.
Motion blur is the apparent streaking of moving objects in a photograph or a sequence of frames, such as a film or animation. It results when the image being recorded changes during the recording of a single exposure, due to rapid movement or long exposure.
Cinematography is the art of motion picture photography.
In camera design, a focal-plane shutter (FPS) is a type of photographic shutter that is positioned immediately in front of the focal plane of the camera, that is, right in front of the photographic film or image sensor.
The Canon EOS 20D is an 8.2-megapixel semi-professional digital single-lens reflex camera, initially announced on 19 August 2004 at a recommended retail price of US$1,499. It is the successor of the EOS 10D, and was succeeded by the EOS 30D in August 2006. It accepts EF and EF-S lenses and uses an APS-C sized image sensor.
A digital single-lens reflex camera is a digital camera that combines the optics and mechanisms of a single-lens reflex camera with a solid-state image sensor and digitally records the images from the sensor.
The science of photography is the use of chemistry and physics in all aspects of photography. This applies to the camera, its lenses, physical operation of the camera, electronic camera internals, and the process of developing film in order to take and develop pictures properly.
In photography, shutter lag is the delay between triggering the shutter and when the photograph is actually recorded. This is a common problem in the photography of fast-moving objects or animals and people in motion. The term narrowly refers only to shutter effects, but more broadly refers to all lag between when the shutter button is pressed and when the photo is taken, including metering and focus lag.
In photography, a shutter is a device that allows light to pass for a determined period, exposing photographic film or a photosensitive digital sensor to light in order to capture a permanent image of a scene. A shutter can also be used to allow pulses of light to pass outwards, as seen in a movie projector or a signal lamp. A shutter of variable speed is used to control exposure time of the film. The shutter is constructed so that it automatically closes after a certain required time interval. The speed of the shutter is controlled either automatically by the camera based on the overall settings of the camera, manually through digital settings, or manually by a ring outside the camera on which various timings are marked.
In photography, through-the-lens metering refers to a feature of cameras whereby the intensity of light reflected from the scene is measured through the lens; as opposed to using a separate metering window or external hand-held light meter. In some cameras various TTL metering modes can be selected. This information can then be used to set the optimal film or image sensor exposure, it can also be used to control the amount of light emitted by a flash unit connected to the camera.
High-speed photography is the science of taking pictures of very fast phenomena. In 1948, the Society of Motion Picture and Television Engineers (SMPTE) defined high-speed photography as any set of photographs captured by a camera capable of 69 frames per second or greater, and of at least three consecutive frames. High-speed photography can be considered to be the opposite of time-lapse photography.
An image sensor or imager is a sensor that detects and conveys information used to form an image. It does so by converting the variable attenuation of light waves into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, camera phones, optical mouse devices, medical imaging equipment, night vision equipment such as thermal imaging devices, radar, sonar, and others. As technology changes, electronic and digital imaging tends to replace chemical and analog imaging.
An active-pixel sensor (APS) is an image sensor, which was invented by Peter J.W. Noble in 1968, where each pixel sensor unit cell has a photodetector and one or more active transistors. In a metal–oxide–semiconductor (MOS) active-pixel sensor, MOS field-effect transistors (MOSFETs) are used as amplifiers. There are different types of APS, including the early NMOS APS and the now much more common complementary MOS (CMOS) APS, also known as the CMOS sensor. CMOS sensors are used in digital camera technologies such as cell phone cameras, web cameras, most modern digital pocket cameras, most digital single-lens reflex cameras (DSLRs), mirrorless interchangeable-lens cameras (MILCs), and lensless imaging for cells.
Sony Corporation produces professional, consumer, and prosumer camcorders such as studio and broadcast, digital cinema cameras, camcorders, pan-tilt-zoom and remote cameras.
The Nikon Expeed image/video processors are media processors for Nikon's digital cameras. They perform a large number of tasks: Bayer filtering, demosaicing, image sensor corrections/dark-frame subtraction, image noise reduction, image sharpening, image scaling, gamma correction, image enhancement/Active D-Lighting, colorspace conversion, chroma subsampling, framerate conversion, lens distortion/chromatic aberration correction, image compression/JPEG encoding, video compression, display/video interface driving, digital image editing, face detection, audio processing/compression/encoding and computer data storage/data transmission.
Strip photography, or slit photography, is a photographic technique of capturing a two-dimensional image as a sequence of one-dimensional images over time, in contrast to a normal photo which is a single two-dimensional image at one point in time. A moving scene is recorded, over a period of time, using a camera that observes a narrow strip rather than the full field. If the subject is moving through this observed strip at constant speed, they will appear in the finished photo as a visible object. Stationary objects, like the background, will be the same the whole way across the photo and appear as stripes along the time axis; see examples on this page.
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A photo exhibiting partial exposure. Lighting conditions changed between the exposure of the top and bottom parts of the photo.
Simulated effect of a rolling shutter on a spinning disc
Skewing in a photograph taken from a car moving at 80 km/h (50 mph). Objects in the foreground, such as the fence and gate, have become skewed, while more distant objects in the background, such as the cliff, remain as normal.
