Editing Jaggies

{{short description|Jagged effect produced by naive upscaling of raster shapes with few pixels defining a curve}}
[[Image:Test nn.gif|right|frame|This image was scaled up using [[nearest-neighbor interpolation]]. Thus, the "jaggies" on the edges of the symbols became more prominent.]]
'''Jaggies''' are artifacts in [[raster image]]s, most frequently from [[aliasing]],<ref>{{Cite web |last=Mitchell |first=Don P. |title=The Antialiasing Problem in Ray Tracing |url=http://www.mentallandscape.com/Papers_siggraph90tutorial.pdf |url-status=live |archive-url=https://web.archive.org/web/20081114111536/http://www.mentallandscape.com/Papers_siggraph90tutorial.pdf |archive-date=2008-11-14 |access-date=2009-04-16}}</ref> which in turn is often caused by non-linear mixing effects producing high-frequency components, or missing or poor [[anti-aliasing filter]]ing prior to sampling.

Jaggies are stair-like lines that appear where there should be "smooth" straight lines or curves. For example, when a nominally straight, un-aliased line steps across one pixel either horizontally or vertically, a "dogleg" occurs halfway through the line, where it crosses the threshold from one pixel to the other.

Jaggies should not be confused with most [[compression artifact]]s, which are a different phenomenon.

== Causes ==
Jaggies occur due to the "staircase effect". This is because a line represented in raster mode is approximated by a sequence of pixels. Jaggies can occur for a variety of reasons, the most common being that the output device ([[Computer display|display monitor]] or [[Computer printer|printer]]) does not have sufficient [[Display resolution|resolution]] to portray a smooth line.<ref>{{Cite magazine |date=March 1996 |title=The Next Generation 1996 Lexicon A to Z: Jaggies |magazine=[[Next Generation (magazine)|Next Generation]] |publisher=[[Imagine Media]] |issue=15 |page=35}}</ref> In addition, jaggies often occur when a bit-mapped image is scaled to a higher resolution. This is one of the advantages that [[vector graphics]] have over [[bitmapped graphics]] – a vector image can be losslessly scaled to any arbitrary resolution or stretched infinitely in either axis without introducing jaggies.

== Solutions ==
The effect of jaggies can be reduced by a graphics technique known as [[spatial anti-aliasing]]. Anti-aliasing smooths out jagged lines by surrounding them with transparent [[pixel]]s to simulate the appearance of fractionally-filled pixels when viewed at a distance. The downside of anti-aliasing is that it reduces contrast – rather than sharp black/white transitions, there are shades of gray – and the resulting image can appear fuzzy. This is an inescapable trade-off: if the resolution is insufficient to display the desired detail, the output will either be jagged, fuzzy, or some combination thereof. While machine learning-based [[Image scaling#Real-time scaling|upscaling]] techniques such as DLSS can be used to infer this missing information, other types of [[Visual artifact|artifacts]] may be introduced in the process.<ref>{{Cite web |date=2024-02-14 |title=Is Upscaling Useful at Lower Resolutions? Nvidia DLSS vs Native at 1080p |url=https://www.techspot.com/article/2803-dlss-vs-native-1080p/ |access-date=2024-12-23 |website=TechSpot |language=en-US}}</ref>

In [[3D rendering#Real-time|real-time 3D rendering]] such as in video games, various anti-aliasing techniques are used to remove jaggies created by the edges of polygons and other contrasting lines. Since anti-aliasing can impose a significant performance overhead, games for home computers often allow users to choose the level and type of anti-aliasing in use in order to optimize their experience, whereas on consoles this setting is typically fixed for each title to ensure a consistent experience. While anti-aliasing is generally implemented through [[Graphics library|graphics APIs]] like [[DirectX]] and [[Vulkan]], some consoles such as the [[Xbox 360]] and [[PlayStation 3]] are also capable of anti-aliasing to little direct performance cost by way of dedicated hardware which performs anti-aliasing on the contents of the framebuffer once it has been rendered by the GPU.<ref>{{Cite web |last=Leadbetter |first=Richard |last2= |first2= |date=2010-01-16 |title=The Anti-Aliasing Effect |url=https://www.eurogamer.net/the-anti-aliasing-effect-article |access-date=2024-12-23 |website=Eurogamer.net |language=en}}</ref> Jaggies in bitmaps, such as sprites and surface materials, are most often dealt with by separate [[texture filtering]] routines, which are far easier to perform than anti-aliasing filtering. Texture filtering became ubiquitous on PCs after the introduction of [[3Dfx]]'s Voodoo GPU.

== Notable uses of the term ==
In the 1985 game ''[[Rescue on Fractalus!]]'' for the [[Atari 8-bit computers]], the graphics depicting the cockpit of the player's spacecraft contains two window struts, which are not anti-aliased and are therefore very "jagged". The developers made fun of this and named the in-game enemies "Jaggi", and also initially titled the game ''Behind Jaggi Lines!''. The latter idea was scrapped by the marketing department before release.<ref>{{Cite web |last=Hague |first=James |title=Interview with David Fox |url=http://www.dadgum.com/halcyon/BOOK/FOX.HTM |url-status=live |archive-url=https://web.archive.org/web/20081208112929/http://www.dadgum.com/halcyon/BOOK/FOX.HTM |archive-date=2008-12-08 |access-date=2008-10-10}}</ref>

== See also ==
* [[Posterization]]

==References==
{{reflist}}

[[Category:Computer graphic artifacts]]
[[Category:Image processing]]