Jaggies
Jaggies are artifacts in
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 artifacts, 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 (
Solutions
The effect of jaggies can be reduced somewhat by a graphics technique known as spatial anti-aliasing. Anti-aliasing smooths out jagged lines by surrounding the jaggies with transparent pixels to simulate the appearance of fractionally-filled pixels. 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 is fuzzy. This is an inescapable trade-off: if the resolution is insufficient to display the desired detail, the output will either be jagged or fuzzy, or some combination thereof.
In addition, jaggies often occur when a bit mapped image is converted to a different resolution. They can occur for variety of reasons, the most common being that the output device (display monitor or printer) does not have enough resolution to portray a smooth line.
In real-time computer graphics, especially gaming, anti-aliasing is used to remove jaggies created by the edges of polygons and other lines entirely. Some video game developers do not enable anti-aliasing by default for their games because the intended hardware is not powerful enough to run it at smooth
Notable uses of the term
In the
See also
References
- ^ Mitchell, Don P. "The Antialiasing Problem in Ray Tracing" (PDF). Archived (PDF) from the original on 2008-11-14. Retrieved 2009-04-16.
- Imagine Media. March 1996. p. 35.
- ^ Hague, James. "Interview with David Fox". Archived from the original on 2008-12-08. Retrieved 2008-10-10.