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Motion Blur

 
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Motion blur is the apparent streaking of rapidly moving objects in a still image
Photography

Photography is the process, activity and art of creating still or moving by recording radiation on a sensitive medium, such as a photographic film, or an ....
 or a sequence of images such as a movie
Film

Film encompasses individual motion pictures, the field of film as an art form, and the film industry. Films are produced by recording images from the world with cameras, or by creating images using animation techniques or special effects....
 or animation
Animation

Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement. It is an optical illusion of Motion due to the phenomenon of persistence of vision, and can be created and demonstrated in a number of ways....
.

a camera
Camera

A camera is a device that records images, either as a still photograph or as moving images known as videos or movies. The term comes from the camera obscura , an early mechanism of projecting images where an entire room functioned as a real-time imaging system; the modern camera evolved from the camera obscura....
 creates an image, that image does not represent a single instant of time.






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Motion blur is the apparent streaking of rapidly moving objects in a still image
Photography

Photography is the process, activity and art of creating still or moving by recording radiation on a sensitive medium, such as a photographic film, or an ....
 or a sequence of images such as a movie
Film

Film encompasses individual motion pictures, the field of film as an art form, and the film industry. Films are produced by recording images from the world with cameras, or by creating images using animation techniques or special effects....
 or animation
Animation

Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement. It is an optical illusion of Motion due to the phenomenon of persistence of vision, and can be created and demonstrated in a number of ways....
.

Applications of motion blur


Photography

When a camera
Camera

A camera is a device that records images, either as a still photograph or as moving images known as videos or movies. The term comes from the camera obscura , an early mechanism of projecting images where an entire room functioned as a real-time imaging system; the modern camera evolved from the camera obscura....
 creates an image, that image does not represent a single instant of time. Because of technological constraints or artistic requirements, the image represents the scene over a period of time. As objects in a scene move, an image of that scene must represent an integration
Integral

Integration is an important concept in mathematics, specifically in the field of calculus and, more broadly, mathematical analysis. Given a function ƒ of a Real number variable x and an interval [a, b] of the real line, the integral...
 of all positions of those objects, as well as the camera's viewpoint, over the period of exposure
Exposure (photography)

In photography, exposure is the total amount of light allowed to fall on the photographic medium during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value and scene luminance over a specified area....
 determined by the shutter speed
Shutter speed

File:Sparklers with a slow shutter speed.JPGIn photography, shutter speed is a common term used to discuss exposure time, the effective length of time a shutter is open; the total Exposure is proportional to this exposure time, or duration of light reaching the Photographic film or ....
. In such an image, any object moving with respect to the camera will look blurred or smeared along the direction of relative motion. This smearing may occur on an object that is moving or on a static background if the camera is moving. In a film
Film

Film encompasses individual motion pictures, the field of film as an art form, and the film industry. Films are produced by recording images from the world with cameras, or by creating images using animation techniques or special effects....
 or television
Television

Television is a widely used telecommunication mass-media for transmitting and receiving moving , either monochrome or color, usually accompanied by sound....
 image, this looks natural because the human eye behaves in much the same way.

Because the effect is caused by the relative motion between the camera, and the objects and scene, motion blur may be avoided by panning
Panning (camera)

In photography, panning refers to the horizontal movement or rotation of a still camera or video camera, or the scanning of a subject horizontally on video or a display device....
 the camera to track those moving objects. In this case, even with long exposure times, the objects will appear sharper, and the background more blurred.

Computer animation

Similarly, in real-time computer animation each frame shows a perfect instant in time (analogous to a camera with an infinitely fast shutter), with zero motion blur. This is why a video game with a frame rate of 25-30 frames per second will seem staggered, while natural motion filmed at the same frame rate appears rather more continuous. Many next generation video games feature motion blur, especially vehicle simulation game
Vehicle simulation game

Vehicle simulation games are a genre of video games which attempt to provide the player with a realistic interpretation of operating various kinds of vehicles....
s. In pre-rendered computer animation, such as CGI movies, realistic motion blur can be drawn because the renderer has more time to draw each frame. Temporal anti-aliasing
Temporal anti-aliasing

Temporal anti-aliasing seeks to reduce or remove the effects of temporal aliasing, which results from insufficient temporal sampling. A common example of temporal aliasing in film is the appearance of vehicle wheels travelling backwards, the so-called Wagon-wheel effect....
 produces frames as a composite of many instants.

Negative effects of motion blur

In televised sport
Sport

Sport is an activity that is governed by a set of regulation of sport or traditions and often engaged in competitively. Sports commonly refer to activities where the physical capabilities of the competitor are the sole or primary determinant of the outcome , but the term is also used to include activities such as mind sports and motor...
s, where conventional cameras expose pictures 25 or 30 times per second, motion blur can be inconvenient because it obscures the exact position of a projectile or athlete in slow motion
Slow motion

Slow motion or slowmo is an effect in film-making whereby time appears to be slowed down. It was invented by Austrian August Musger. Typically this style is achieved when each film frame is captured at a rate much faster than it will be played back....
. For this reason special cameras are often used which eliminate motion blurring by taking rapid exposures on the order of 1/1000 of a second, and then transmitting them over the course of the next 1/25 or 1/30 of a second. Although this gives sharper slow motion replays it can look strange at normal speed because the eye expects to see motion blurring and does not.

Sometimes, motion blur can be removed from images with the help of deconvolution
Deconvolution

In mathematics, deconvolution is an Algorithm process used to reverse the effects of convolution on recorded data. The concept of deconvolution is widely used in the techniques of signal processing and ....
.

Restoration

An example of blurred image restoration with Wiener deconvolution
Wiener deconvolution

In mathematics, Wiener deconvolution is an application of the Wiener filter to the noise problems inherent in deconvolution. It works in the frequency domain, attempting to minimize the impact of deconvoluted noise at frequencies which have a poor signal-to-noise ratio....
:

Gallery

Image:City lights in motion.jpg|These city lights were still; it was the camera's orientation that changed during the exposure. The dashed pattern the individual lights trace is due to alternating current
Alternating current

In alternating current the movement of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again....
. Image:Truck with motion blur.jpg|Both the truck and the camera moved during this exposure. The camera was moved, or panned, in order to remain pointed at the truck's driver-side door. That is why the ground appears to move past the truck. Image:Motorbike rider mono.jpg|Motion blur is frequently employed in sports photography (particularly motor sports) to show a sense of speed. To achieve this effect it is necessary to use a slow shutter speed and pan the lens of the camera in time with the motion of the object

Image:Nightly Rotation above San Jose International Airport.jpg|Taken aboard an airplane rotating above San Jose at night. The city lights form concentric strips. Image:Motion blur.JPG|The vehicles and objects within this picture appear distorted due to to quick camera movements. Image:Tj pullingout.jpg|The traffic on this street leaves brilliant streaks due to the low shutter speed of the camera and the cars' relatively fast speed.