question: How is blurring added to photos and videos and how can be removed?
comment: Natural blurring in photos and videos is from the focal point and depth of field. This cannot be removed. Blurring by software can be altered but will be different in case by case scenarios.
passages: Image restoration
  
  Image Restoration is the operation of taking a corrupt/noisy image and estimating the clean, original image. Corruption may come in many forms such as motion blur, noise and camera mis-focus. Image restoration is performed by reversing the process that blurred the image and such is performed by imaging a point source and use the point source image, which is called the Point Spread Function (PSF) to restore the image information lost to the blurring process.
   In order to identify the size of the blur (needed to decode depth information) in the captured image, two approaches can be used: 1) deblurring the captured image with different blurs, or 2) learning some linear filters that identify the type of blur.
   When a camera lens is focused to project an object some distance away onto the film or detector, the objects that are closer in distance, relative to the distant object, are also "approximately" in focus. The range of distances that are nearly in focus is called the depth of field. Depth of field generally increases with decreasing aperture diameter (increasing f-number). The unfocused blur outside the depth of field is sometimes used for artistic effect in photography. The subjective appearance of this blur is known as bokeh.
   Many graphical software products (e.g. Adobe Photoshop or GIMP) offer simple motion blur filters. However, for advanced motion blur filtering including curves or non-uniform speed adjustment, specialized software products (e.g. VirtualRig Studio) are necessary.
  
  Section::::Applications of motion blur.:Biology.
   Some still camera manufacturers marketed their cameras as having digital image stabilization when they really only had a high-sensitivity mode that uses a short exposure time—producing pictures with less motion blur, but more noise. It reduces blur when photographing something that is moving, as well as from camera shake.
  
  Others now also use digital signal processing (DSP) to reduce blur in stills, for example by sub-dividing the exposure into several shorter exposures in rapid succession, discarding blurred ones, re-aligning the sharpest sub-exposures and adding them together, and using the gyroscope to detect the best time to take each frame.
   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.
  
  Section::::Applications of motion blur.:Animation.
  
  In computer animation this effect must be simulated as a virtual camera actually does capture a discrete moment in time. This simulated motion blur is typically applied when either the camera or objects in the scene move rapidly.
   The double effort is typically used to mutually compensate for the intrinsical weaknesses of the various methods in order to increase the overall reliability and accuracy or to speed up AF function.
   The first approach uses correct mathematical deconvolution that takes account of the known aperture design pattern; this deconvolution can identify where and by what degree the scene has become convoluted by out of focus light selectively falling on the capture surface, and reverse the process. Thus the blur-free scene may be retrieved together with the size of the blur.
   Image stabilization
  
  Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure.
   In video games the use or not of motion blur is somewhat controversial. Some gamers claim that the blur actually makes gaming worse since it does blur images, making more difficult to recognize objects, especially in fast-paced moments. This does become noticeable the lower the frame rate is. Improvements in the visual quality of modern post-process motion blur shaders as well as a tendency towards high frame rate video games has lessened the visual detriment of undersampled motion blur effects.
  
  Section::::Restoration.
  
  An example of blurred image restoration with Wiener deconvolution:
  
  Section::::See also.
   Section::::Image editor features.:Sharpening and softening images.
  
  Graphics programs can be used to both sharpen and blur images in a number of ways, such as unsharp masking or deconvolution. Portraits often appear more pleasing when selectively softened (particularly the skin and the background) to better make the subject stand out. This can be achieved with a camera by using a large aperture, or in the image editor by making a selection and then blurring it. Edge enhancement is an extremely common technique used to make images appear sharper, although purists frown on the result as appearing unnatural.
   However, image stabilization does "not" prevent motion blur caused by the movement of the subject or by extreme movements of the camera. Image stabilization is only designed for and capable of reducing blur that results from normal, minute shaking of a lens due to hand-held shooting. Some lenses and camera bodies include a secondary panning mode or a more aggressive 'active mode', both described in greater detail below under optical image stabilization.
   BULLET::::- Some newer lenses include an Image Stabilizer which can automatically detect whether the user is panning and respond accordingly, and therefore these lenses do not have an IS mode switch.
  
  All EF lenses that support IS have the words "Image Stabilizer" written on the lens. On some of Canon's larger telephoto lenses, the words "Image Stabilizer" are etched onto a metal plate affixed to the lens.
  
  Section::::Related technologies.:Diffractive optics.
   Section::::Trap focus.:AI Servo.
   Section::::Active.
  
  Active AF systems measure distance to the subject independently of the optical system, and subsequently adjust the optical system for correct focus.
   BULLET::::- A-DEP: Canon also offers A-DEP ("Automatic DEPth of field") mode on some cameras, which sets the depth of field and focus in a single shot. However, this requires lining up both the nearest and further objects on autofocus points at the same time, which may be difficult.
   BULLET::::- Image sharpen & reinstatement –
  
  BULLET::::- Image sharpens & reinstatement is the procedure of images which is capture by the contemporary camera making them an improved picture or manipulating the pictures in the way to get chosen product. This comprises the zooming process, the blurring process, the sharpening process, the gray scale to color translation process, the picture recovery process and the picture identification process.
  
  BULLET::::- Facial Recognition –
   Unsharp masking allows the photographer to sharpen areas that have become blurred in the original negative, due to long shutter speed/exposure time, or from using a wide aperture/"fast" lens.
  
  When creating the unsharp mask, extra space or diffusing material is added between the image and the mask to produce the necessary blur.
  
  Section::::In photography.:Unsharp masking.:Digital.
   If the camera lens is focused at or beyond its hyperfocal distance, then the depth of field becomes large, covering everything from half the hyperfocal distance to infinity. This effect is used to make "focus free" or fixed-focus cameras.
  
  Section::::Motion blur.
  
  Motion blur is caused when either the camera or the subject moves during the exposure. This causes a distinctive streaky appearance to the moving object or the entire picture (in the case of camera shake).
   This lens is compatible with the Canon Extender EF teleconverters on newer EOS bodies. Autofocus works with the 1.4× Extender (and only with cameras that can autofocus at f/8) and image stabilization (IS) works with both 1.4× and 2× Extenders.
  
  Section::::Version II.
  
  The new Canon EF 100-400mm f/4.5-5.6L IS II USM was announced on 11 November 2014 (10 November in the United States due to time zone differences from Japan), with availability expected the following month. Among the changes from the Mark I version are:
   Section::::Techniques.:Optical image stabilization.:Sensor-shift.
   Note that demosaicing is only performed for CFA sensors; it is not required for 3CCD or Foveon X3 sensors.
  
  Cameras and image processing software may also perform additional processing to improve image quality, for example:
  
  BULLET::::- removal of systematic noise – bias frame subtraction and flat-field correction
  
  BULLET::::- dark frame subtraction
  
  BULLET::::- optical correction – lens distortion, vignetting, chromatic aberration and color fringing correction
  
  BULLET::::- contrast manipulation
  
  BULLET::::- increasing visual acuity by unsharp masking
  
  BULLET::::- dynamic range compression – lighten shadow regions without blowing out highlight regions
   BULLET::::- Hugin can be used to correct distortion, though that is not its primary application.
  
  Besides these systems that address images, there are some that also adjust distortion parameters for videos:
  
  BULLET::::- FFMPEG using the "lenscorrection" video filter.
  
  BULLET::::- Blender by using the node editor to insert a "Distort/Lens Distortion" node between the input and output nodes.
  
  Section::::Related phenomena.
   Some digital cameras allow cropping and enlarging of a captured image, in order to emulate the effect of a longer focal length zoom lens (narrower angle of view). This is commonly known as digital zoom and produces an image of lower optical resolution than optical zoom. Exactly the same effect can be obtained by using digital image processing software on a computer to crop the digital image and enlarge the cropped area. Many digital cameras have both, combining them by first using the optical, then the digital zoom.
   An alternative mechanical mechanism has been proposed for generating bokeh in small aperture cameras such as compacts or cellphone cameras, called image destabilisation, in which both the lens and sensor are moved in order to maintain focus at one focal plane, while defocusing nearby ones. This effect currently generates blur in only one axis.
  
presuppositions: Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos and can possibly be removed.  Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos.
corrections: Natural blurring is inherent in photos and videos due to focal point and depth of field and cannot be removed, however blurring by software can be altered.  Natural blurring cannot be removed due to it being from the focal point and depth of field, however blurring by software can always be altered. Nature blurring is inherent in photos and videos due to focal point and depth of field, although blurring by software can be removed.  Natural blurring cannot be removed because it is inherent in photos and videos due to focal point and depth of field, however blurring from software can be altered. Natural blurring cannot be removed as it comes from the focal point and depth of field, however blurring software can be removed.  Natural blurring is inherent in photos and videos due to focal point and depth of field and cannot be removed, however blurring via software can be altered. 
raw_presuppositions: Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos and can possibly be removed.  Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos. Blurring is an effect that is added to photos and videos.
raw_corrections: Natural blurring is inherent in photos and videos due to focal point and depth of field and cannot be removed, however blurring by software can be altered.  Natural blurring cannot be removed due to it being from the focal point and depth of field, however blurring by software can always be altered. Nature blurring is inherent in photos and videos due to focal point and depth of field, although blurring by software can be removed.  Natural blurring cannot be removed because it is inherent in photos and videos due to focal point and depth of field, however blurring from software can be altered. Natural blurring cannot be removed as it comes from the focal point and depth of field, however blurring software can be removed.  Natural blurring is inherent in photos and videos due to focal point and depth of field and cannot be removed, however blurring via software can be altered.  Blurring is inherent in photos and videos due to focal point and depth of field.