Applications of motion blur Photography
Photography
Motion blur in photography. When a
camera 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 of all positions of those objects, as well as the camera's viewpoint, over the period of exposure determined by the shutter speed. 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 or television image, this looks natural because the human eye behaves in much the same way.
This amusement ride moved during the exposure.
Motion blur is controlled by your camera’s shutter speed, which is the amount of time the shutter stays open so light can hit the camera’s sensor. If something in the scene moves while your shutter is open, it will blur in the final image. This means that slower shutter speeds generally show more motion blur.
Because the effect is caused by the relative motion between the camera, and the objects and scene, motion blur may be avoided by
panning 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 games. 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 produces frames as a composite of many instants.
Negative effects of motion blur
In televised sports, 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. 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.
Restoration
An example of blurred image restoration with Wiener deconvolution:
Gallery
From left: original image, blurred image and de-blurred image. Notice some artifacts in de-blurred image.
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