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Topic: Dithering


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In the News (Sat 2 Jun 12)

  
  GRAPHICS: Dithering
Dithering is the most common means of reducing the color range of images down to the 256 (or fewer) colors seen in 8-bit GIF images.
Dithering is the process of juxtaposing pixels of two colors to create the illusion that a third color is present.
Most images are dithered in a diffusion or randomized pattern to diminish the harsh transition from one color to another.
www.webstyleguide.com /graphics/dither.html   (399 words)

  
  www.pcrecording.com
The lower level bits are filled in with the dither noise and become the least significant bits (in terms of amplitude) in the 24-bit signal.
However, through a process of noise shaping, the dither noise we introduced can be resampled and directed to frequency ranges that nearly exceed the capacity of the human ear to hear it.
Dithering is necessary only when you go from a bit rate that is higher to one that is lower.
www.pcrecording.com /dither.htm   (1671 words)

  
 Dither Information
Dither is a form of noise, or 'erroneous' signal or data which is added to sample data for the purpose of minimizing quantization error.
Dithering is a technique used in computer graphics to create the illusion of color depth in images with a limited color palette (color quantization).
Dithering such as this, in which the computer's display hardware is the primary limitation on color depth, is commonly employed in software such as web browsers.
www.bookrags.com /wiki/Dither   (2591 words)

  
 VIEWS Visualization Project: Dithering of Alpha for Increased Image Quality
This work describes and analyzes a technique for accurately specifying small values of alpha that would normally not be possible due to the limited precision (number of bits) allowed for the alpha channel in graphics hardware.
The images on the left were generated without alpha dithering, those on the right with alpha dithering.
As the number of slices increases, the alpha values decrease to the point where small alpha values lose precision unless dithering is used.
www.llnl.gov /icc/sdd/img/dithering.shtml   (173 words)

  
 General Advice on Dithering HST Observations
A dither is defined here as an offset in either spatial, or in the case of spectroscopic observations dispersion coordinates, usually for the purpose of recovering resolution with sub-pixel offsets, or ameliorating background irregularities with multi-pixel offsets.
Dithering of HST observations is hardly new; indeed the primary data acquisition modes of both the GHRS and FOS involved both sub- and multi-pixel (diodes) offsets to obtain well-sampled data without gaps resulting from the presence of a few dead diodes.
Rapid dithering can impose additional load on the full system in terms of command volume needed to execute the observations, overheads for science data buffer dump management and in the volume of data that must be processed through the pipeline.
www.stsci.edu:8083 /hst/wfpc2/analysis/wfpc2_dither_all.html   (3427 words)

  
 Dr. Dobb's | A Balanced Dithering Technique | April 15, 2003
A dithering algorithm selects colors from the palette and assigns them to the pixels in a given region such that their average value is close to the desired color or gray scale.
Ordered dither has the advantage that the dithering of one pixel does not influence the dithering of surrounding pixels; that is, the dither is "localized." This is especially useful when the dithered image is used in an animation sequence.
For example, when dithering a gray-level image to fl and white, every pixel is mapped to either fl (level 0) or white (level 255), and the error introduced by this mapping is in the range -127 to +128 for every pixel (this is the quantization error).
www.ddj.com /dept/cpp/184403590?pgno=5   (1935 words)

  
 Dithering - good, bad, and ugly
Dithering refers to the interpolation of unavailable colors by mixing pixels of (usually two) available colors in certain patterns and ratios.
When the dither pattern is very tight, with available colors in nearly equal quantities, the resulting appearance can be very good, sometimes nearly indistinguishable from a nondithered image (demonstrated in the DitherBox plug-in promo materials).
Dithering becomes objectionable when the pattern is diffuse, and when the palette used is obviously alien to the original image.
style.cleverchimp.com /dithering   (1733 words)

  
 Harmony Central - Much Ado About Dithering
Dithering is a concept that, in its most basic form, adds noise to the very lower-level signals, thus using the data in those least significant bits to influence the sound of the more significant bits.
Dithered or not, when a 24-bit signal ends up on a 16-bit CD, eight bits are truncated and never heard from again.
Dithering should happen only when converting a high bit-rate source format to its final, 16-bit, mixed-for-CD format (and in the years to come, we'll probably be dithering our 32 or 64-bit internal processing systems down to 24 bits for whatever high-resolution format finally takes off).
www.harmony-central.com /articles/tips/dithering   (1510 words)

  
 Graphics: Minimize Dithering - reduce banding diffusion dithering in gif png for smaller optimized images
Dithering is the process of changing pixels in these color transition zones to minimize banding.
The colorful balloon at 32 colors and 100% diffusion dithered is 8,277 bytes, at 85% dithered the dithering was less apparent, and it weighs in at 7,975 bytes.
The final dithered and lossy 64-color image has the smooth look of a higher bit-depth image yet nearly the same file size as the 64-color image with no dithering.
www.websiteoptimization.com /speed/tweak/dithering   (824 words)

  
 Dithering - virtualdub.org
It turns out that if you are doing this, you can get the dithering for cheap by folding the multiply into the clip table, and then offsetting the pointer used for indexing into it according to each pixel.
It's not exactly correct, as this scales the dithering matrix by whatever factor was folded into the table, but for most uses it's close enough, and it's basically free.
You can decrease the mean error by subtracting off the dither matrix, but if you want to decrease the graininess of the image you need to do some intelligent averaging or some other sort of estimation too.
www.virtualdub.org /blog/pivot/entry.php?id=151   (1940 words)

  
 Dithering
Dithering is a process whereby the guide star is moved between successive exposures, causing the resultant image to land on a different set of pixels from one to the other.
In one case, the image was undithered, in the other the image was dithered to the maximum.
Also, dithering has the ability to increase the background SNR by a significant amount.
www.hiddenloft.com /notes/dithering.htm   (1228 words)

  
 Dithering
Dithering is an imaging technique which allows a bitmap (or a bitmapped device, such as a screen or printer) to appear to display more colors than are actually possible.
This can be a significant problem when dithering images containing naturalistic images (for example, photographs), and tends to be particularly noticeable when dithering is used on relatively low resolution devices.
For example, if we had an image which contained areas that had been dithered (like the examples above) to produce orange and various shades of gray, there is no simple way to adjust the color of those areas, because each area contains a mix of pixels of different colors.
www.graphicsacademy.com /what_dither.php   (569 words)

  
 Dithering - Dictionary Definition and Meaning of Dithering
Dithering is used in computer graphics to create additional colors and shades from an existing palette by interspersing pixels of different colours.
There are three types: regular dithering which uses a very regular predefined pattern; random dither where the pattern is a random noise; and pseudo random dither which uses a very large, very regular, predefined pattern.
Dithering is used to create patterns for use as backgrounds, fills and shading, as well as for creating halftones for printing.
www.wordiq.com /define/dithering.html   (261 words)

  
 Bit Depth - Color Palettes - Dithering   (Site not responding. Last check: )
Dithering is the process of making an 8-bit image with a 256-color palette simulate a 24-bit image with a full-color palette.
For example, dithering is required to display a full-color image on older computers that have only a 256-color graphics card because those computers must simulate colors they can't actually display.
First, although at a distance the human eye merges dithered patterns into another color, up close the image appears speckled.
www.ou.edu /class/digitalmedia/articles/ColorPalettes_Dithering_BitDepth.html   (915 words)

  
 [No title]
Ordered dither represents a major improvement in digital halftoning where this spatial distortion was eliminated and the image could then be rendered in its original size.
In fact, the clustered-dot ordered dither is the process used by most newspapers, and in the computer imaging world the term "halftoning" has come to refer to this method if not otherwise qualified.
Dithering with white noise, on the other hand, introduces enough randomness to suppress the artifacting and the gridlike appearance, but the low- frequency component of this noise introduces graininess.
www.efg2.com /Lab/Library/ImageProcessing/DHALF.TXT   (8478 words)

  
 Color dithering in Gif images
Dithering of colors in gif images leads to large file size and how you can optimize the gif image by removing the dither.
Dithering is a process by which pixels of two colors are placed very close to each other so that the human eye is not able to distinguish the colors individually but, rather, sees a new color that is the combination of the two.
Dithering is an attempt to produce the desired color by a combination of two or more colors.
www.webdevelopersnotes.com /graphics/dithering_in_gifs.php3   (308 words)

  
 24-bit to 16-bit dithering - mLAN Forums. Discuss mLAN issues with people all over the world. - Forums powered by ...
During mastering in Cubase, the Dither plugin should be the last plugin on the output channel before export.
As Frank said, dithering must be at least mentioned in the manual and I must try to locate the plugin for it.
Dithering is explained in detail on page 12 of the "Plug-in Reference" manual (.pdf file) that is included on your C4 DVD.
www.mlancentral.com /forums/showflat.php?Cat=&Board=Steinberg&Number=294570&Main=294556   (783 words)

  
 Smart Computing Article - directory to dithering   (Site not responding. Last check: )
Dithering comes into play when the computer has a limited color palette to display an image.
Dithering is akin to the halftone process seen in print.
Text also uses a form of dithering to smooth out a character's jagged fl pixels, although this is related more to anti-aliasing.
www.smartcomputing.com /editorial/article.asp?article=articles/archive/r0601/d6/directmemoryaccesstodithering.asp&guid=m7smzcc4   (5636 words)

  
 Dithering, Sampling and Image Reconstruction
Such dithering offers many advantages, particularly for the case in which the original detector pixels are too large to adequately sample the point-spread function of the image falling on them, but can pose a difficult image combination problem.
No amount of dithering can compensate for the loss of information introduced by the convolution with the PRF but we can hope to combine a set of well-dithered images resembling that on the right in Figure 1 to produce a result similar to that at the centre.
However, when multiple dithered input images are available a linear combination of the Fourier transforms may be derived in which the aliasing is suppressed and the Fourier transform of a critically sampled ``super-image'' computed.
www.adass.org /adass/proceedings/adass99/O6-02   (3447 words)

  
 Dithering - virtualdub.org
It turns out that if you are doing this, you can get the dithering for cheap by folding the multiply into the clip table, and then offsetting the pointer used for indexing into it according to each pixel.
It's not exactly correct, as this scales the dithering matrix by whatever factor was folded into the table, but for most uses it's close enough, and it's basically free.
You can decrease the mean error by subtracting off the dither matrix, but if you want to decrease the graininess of the image you need to do some intelligent averaging or some other sort of estimation too.
virtualdub.org /blog/pivot/entry.php?id=151   (1639 words)

  
 Graphics Definitions   (Site not responding. Last check: )
Dithering is the process of converting an image with a certain bit depth to one with a lower bit depth.
When an application dithers an image, it converts colors that it can not display into patterns of two or more colors that closely resemble the original.
Dithering works because your mind is tricked by the pattern of colors into thinking that it is a different color.
www.bergen.org /AAST/ComputerAnimation/Graph_Dithering.html   (90 words)

  
 APW Dithering
The Veryovka-Buchanan idea to enhance the contours of the image is to distribute the error into block, it means that the image is grouped in pixels block of length 2x2, for example, and calculates the error for each one of the pixels in each block.
This method is the junction of ordered dithering and Floyd-Steinberg dithering plus the texture treatment, using two textures.
This method is the junction of ordered dithering and Floyd-Steinberg dithering plus the texture treatment for to textures and one of textures is rotated in 30, 60 90, 120 and 150 degrees.
www.visgraf.impa.br /Courses/ip00/proj/Dithering1/veryovka_buchanan_dithering.html   (870 words)

  
 What is dithering? - a definition from Whatis.com - see also: dither, dithered
For example, dithering occurs when a color is specified for a Web page that a browser on a particular operating system can't support.
Dithering also occurs when a display monitor attempts to display images specified with more colors than the monitor is equipped to handle.
Dithering is rather easy to confuse with antialiasing.
searchsmb.techtarget.com /sDefinition/0,,sid44_gci211968,00.html   (296 words)

  
 Dithering and antialiasing graphics
Monitors and image files limited to 256 colors can create the illusion of more colors by dithering the available hues in a diffuse pattern of pixels, approximating the desired color.
Dithering is used by operating systems and display applications, such as Web browsers, running on 8-bit monitors.
The alternative to dithering is color substitution, which uses the closest color on the palette.
builder.com.com /5100-31-5075838.html   (269 words)

  
 Floyd-Steinberg Dithering for the Gimp
The Quality of the dithering in the Gimp has improved vastly and the plugin no longer works for Gimp 2.x.
Lets face it: The builtin Floyd Steinberg dithering of gimp is ugly (I think, there is an error in the implementation).
The plugin is not a complete replacement for the builtin dithering, since it can not dither against a given colormap.
www.home.unix-ag.org /simon/gimp/fsdither.html   (104 words)

  
 GrafX-Design.com - General Graphics Tutorials -- Dithering
Dithering is the process that a program uses when it cannot display the full range of colors in a particular image.
Figure 1.2 shows what the image looks like when it is necessary to dither the available colors to arrive at a set of colors that aren't available.
An alternative to dithering is to use only the colors to which the software has access.
www.grafx-design.com /01gen.html   (394 words)

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