Editing Bokeh (section)

==Emulation==
[[Image:Faux-bokeh-comparison.jpg|thumb|upright=1.4|From left to right: an original photo with no bokeh or blur; the same photo with synthetic bokeh effect applied to its background; the same photo with [[Gaussian blur]] applied to its background]]

Bokeh can be simulated by [[convolution|convolving]] the image with a [[integral transform|kernel]] that corresponds to the image of an out-of-focus point source taken with a real camera. Unlike conventional convolution, this convolution has a kernel that depends on the distance of each image point and&nbsp;– at least in principle&nbsp;– has to include image points that are occluded by objects in the foreground.<ref>
{{Citation
 | last1 = Potmesil
 | first1 = M.
 | last2 = Chakravarty
 | first2 = I.
 | year = 1982
 | title = Synthetic Image Generation with a Lens and Aperture Camera Model
 | journal = ACM Trans. Graph.
 | series = ACM Transactions on Graphics
 | publisher = ACM
 | volume = 1
 | issue = 2 (1982)
 | pages = 85–108
 | issn = 0730-0301
 | doi = 10.1145/357299.357300
| s2cid = 9253049
 | doi-access = free
 }}
</ref> Also, bokeh is not just any blur. To a first approximation, defocus blur is convolution by a uniform [[disk (mathematics)|disk]], a more computationally intensive operation than the "standard" [[Gaussian blur]]; the former produces sharp circles around highlights whereas the latter is a much softer effect. [[Diffraction]] may alter the effective shape of the blur. Some graphics editors have a filter to do this, usually called "Lens Blur".<ref>{{cite web|url=http://livedocs.adobe.com/en_US/Photoshop//10.0/help.html?content=WSA75837E3-FE05-4f86-A9DF-3C0DD602CA63.html|author=Adobe Photoshop CS3 Livedocs|title=Add lens blur|access-date=2014-05-23|archive-url=https://web.archive.org/web/20140523225356/http://livedocs.adobe.com/en_US/Photoshop//10.0/help.html?content=WSA75837E3-FE05-4f86-A9DF-3C0DD602CA63.html|archive-date=2014-05-23|url-status=dead}}</ref> Accurate bokeh simulation requires running the blur in linear, HDR space. For low dynamic range images, an [[artificial neural network]] may be used to reconstruct the HDR light.<ref>{{cite arXiv |last1=Zhang |first1=Xuaner |last2=Matzen |first2=Kevin |last3=Nguyen |first3=Vivien |last4=Yao |first4=Dillon |last5=Zhang |first5=You |last6=Ng |first6=Ren |title=Synthetic Defocus and Look-Ahead Autofocus for Casual Videography |date=21 May 2019|class=cs.CV |eprint=1905.06326 }} [https://ceciliavision.github.io/vid-auto-focus/ SIGGRAPH 2019 project page] {{Webarchive|url=https://web.archive.org/web/20230324073704/https://ceciliavision.github.io/vid-auto-focus/ |date=2023-03-24  }}</ref>

An alternative mechanical mechanism has been proposed for generating bokeh in small aperture cameras such as compacts or cellphone cameras, called image destabilisation,<ref>{{cite web |url=https://www.newscientist.com/article/mg20427346.700-nextgeneration-cameras-bring-photography-tricks-to-the-masses.html |first=Jim |last=Giles |work=New Scientist (Subscription required) |title=Next-generation cameras bring photography tricks to the masses |access-date=2011-04-04 |archive-date=2011-11-14  |archive-url=https://web.archive.org/web/20111114015051/http://www.newscientist.com/article/mg20427346.700-nextgeneration-cameras-bring-photography-tricks-to-the-masses.html |url-status=live }}</ref><ref>{{cite web|url=http://web.media.mit.edu/~ankit/id/|author=Ankit Mohan and Douglas Lanman and Shinsaku Hiura and Ramesh Raskar|title=Image Destabilization: Programmable Defocus using Lens and Sensor Motion|url-status=dead|archive-url=https://web.archive.org/web/20090924193620/http://web.media.mit.edu/~ankit/id/|archive-date=2009-09-24}}</ref> 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.

Some advanced digital cameras have bokeh features which take several images with different apertures and focuses and then manually compose them afterward to one image. More advanced systems of bokeh use a hardware system of 2 sensors, one sensor to take photo as usual while other ones record depth information. Bokeh effect and refocusing can then be applied to an image after the photo is taken.<ref>{{cite news |url=http://connect.dpreview.com/post/9386067747/htc-launches-one-m8 |title=HTC launches One M8 with new 'Duo Camera' |author=Lars Rehm |newspaper=Dpreview |date=March 25, 2014 |access-date=2014-03-27  |archive-date=2015-10-03  |archive-url=https://web.archive.org/web/20151003195918/http://connect.dpreview.com/post/9386067747/htc-launches-one-m8 |url-status=live }}</ref>