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🔗 Computer science

Floyd–Steinberg dithering is an image dithering algorithm first published in 1976 by Robert W. Floyd and Louis Steinberg. It is commonly used by image manipulation software, for example when an image is converted into GIF format that is restricted to a maximum of 256 colors.

The algorithm achieves dithering using error diffusion, meaning it pushes (adds) the residual quantization error of a pixel onto its neighboring pixels, to be dealt with later. It spreads the debt out according to the distribution (shown as a map of the neighboring pixels):

${\displaystyle {\begin{bmatrix}&&*&{\frac {\displaystyle 7}{\displaystyle 16}}&\ldots \\\ldots &{\frac {\displaystyle 3}{\displaystyle 16}}&{\frac {\displaystyle 5}{\displaystyle 16}}&{\frac {\displaystyle 1}{\displaystyle 16}}&\ldots \\\end{bmatrix}}}$

The pixel indicated with a star (*) indicates the pixel currently being scanned, and the blank pixels are the previously-scanned pixels. The algorithm scans the image from left to right, top to bottom, quantizing pixel values one by one. Each time the quantization error is transferred to the neighboring pixels, while not affecting the pixels that already have been quantized. Hence, if a number of pixels have been rounded downwards, it becomes more likely that the next pixel is rounded upwards, such that on average, the quantization error is close to zero.

The diffusion coefficients have the property that if the original pixel values are exactly halfway in between the nearest available colors, the dithered result is a checkerboard pattern. For example, 50% grey data could be dithered as a black-and-white checkerboard pattern. For optimal dithering, the counting of quantization errors should be in sufficient accuracy to prevent rounding errors from affecting the result.

In some implementations, the horizontal direction of scan alternates between lines; this is called "serpentine scanning" or boustrophedon transform dithering.

In the following pseudocode we can see the algorithm described above. This works for any approximately linear encoding of pixel values, such as 8-bit integers, 16-bit integers or real numbers in the range [0,1].

for each y from top to bottom do
    for each x from left to right do
        oldpixel := pixel[x][y]
        newpixel := find_closest_palette_color(oldpixel)
        pixel[x][y] := newpixel
        quant_error := oldpixel - newpixel
        pixel[x + 1][y    ] := pixel[x + 1][y    ] + quant_error × 7 / 16
        pixel[x - 1][y + 1] := pixel[x - 1][y + 1] + quant_error × 3 / 16
        pixel[x    ][y + 1] := pixel[x    ][y + 1] + quant_error × 5 / 16
        pixel[x + 1][y + 1] := pixel[x + 1][y + 1] + quant_error × 1 / 16

When converting 16 bit greyscale to 8 bit, find_closest_palette_color() may perform just a simple rounding, for example:

find_closest_palette_color(oldpixel) = round(oldpixel / 256)

The pseudocode can result in pixel values exceeding the valid values (such as greater than 1 in a [0,1] representation). Such values should ideally be clipped by the find_closest_palette_color() function, rather than clipping the intermediate values, since a subsequent error may bring the value back into range. However, if fixed-width integers are used, wrapping of intermediate values would cause inversion of black and white, and so should be avoided.

🔗 United States 🔗 Terrorism 🔗 Socialism 🔗 Michigan 🔗 Chicago

The Weather Underground Organization (WUO), commonly known as the Weather Underground, was a radical left militant organization active in the late 1960s and 1970s, founded on the Ann Arbor campus of the University of Michigan. It was originally called the Weathermen. The WUO organized in 1969 as a faction of Students for a Democratic Society (SDS) largely composed of the national office leadership of SDS and their supporters. Beginning in 1974, the organization's express political goal was to create a revolutionary party to overthrow American imperialism.

The FBI described the WUO as a domestic terrorist group, with revolutionary positions characterized by black power and opposition to the Vietnam War. The WUO took part in domestic attacks such as the jailbreak of Timothy Leary in 1970. The "Days of Rage" was the WUO's first riot in October 1969 in Chicago, timed to coincide with the trial of the Chicago Seven. In 1970, the group issued a "Declaration of a State of War" against the United States government under the name "Weather Underground Organization".

In the 1970s, the WUO conducted a bombing campaign targeting government buildings and several banks. Some attacks were preceded by evacuation warnings, along with threats identifying the particular matter that the attack was intended to protest. Three members of the group were killed in an accidental Greenwich Village townhouse explosion, but none were killed in any of the bombings. The WUO communiqué issued in connection with the bombing of the United States Capitol on March 1, 1971 indicated that it was "in protest of the U.S. invasion of Laos". The WUO asserted that its May 19, 1972 bombing of the Pentagon was "in retaliation for the U.S. bombing raid in Hanoi". The WUO announced that its January 29, 1975 bombing of the United States Department of State building was "in response to the escalation in Vietnam".

The WUO began to disintegrate after the United States reached a peace accord in Vietnam in 1973, and it was defunct by 1977.

The group took its name from Bob Dylan's lyric, "You don't need a weatherman to know which way the wind blows", from the song "Subterranean Homesick Blues" (1965). That Dylan line was also the title of a position paper distributed at an SDS convention in Chicago on June 18, 1969. This founding document called for a "White fighting force" to be allied with the "Black Liberation Movement" and other radical movements to achieve "the destruction of U.S. imperialism and form a classless communist world".

🔗 Color

Cosmic latte is the average color of the universe, found by a team of astronomers from Johns Hopkins University. In 2001, Karl Glazebrook and Ivan Baldry determined that the average color of the universe was a greenish white, but they soon corrected their analysis in a 2002 paper in which they reported that their survey of the light from over 200,000 galaxies averaged to a slightly beigeish white. The hex triplet value for cosmic latte is #FFF8E7.

🔗 United States

The Leary–Lettvin debate was a May 3, 1967 debate between Dr. Jerome Lettvin, a medical doctor and professor at MIT, and Dr. Timothy Leary, a licensed psychologist, about the merits and dangers of the hallucinogenic drug LSD. It took place in the Kresge Auditorium at the Massachusetts Institute of Technology.

🔗 Architecture

Atlantropa, also referred to as Panropa, was a gigantic engineering and colonisation idea devised by the German architect Herman Sörgel in the 1920s and promoted by him until his death in 1952. Its central feature was a hydroelectric dam to be built across the Strait of Gibraltar, which would have provided enormous amounts of hydroelectricity and would have led to the lowering of the surface of the Mediterranean Sea by up to 200 metres (660 ft), opening up large new lands for settlement, for example in the Adriatic Sea. The project proposed four additional major dams as well:

• Across the Dardanelles to hold back the Black Sea
• Between Sicily and Tunisia to provide a roadway and further lower the inner Mediterranean
• On the Congo River below its Kwah River tributary to refill the Mega-Chad basin around Lake Chad providing fresh water to irrigate the Sahara and creating a shipping lane to the interior of Africa
• Suez Canal extension and locks to maintain Red Sea connection

Sörgel saw his scheme, projected to take over a century, as a peaceful European-wide alternative to the Lebensraum concepts that later became one of the stated reasons for Nazi Germany's conquest of new territories. Atlantropa would provide land and food, employment, electric power, and most of all, a new vision for Europe and neighbouring Africa.

The Atlantropa movement, through its several decades, was characterised by four constants:

• Pacifism, in its promises of using technology in a peaceful way;
• Pan-European sentiment, seeing the project as a way to unite a war-torn Europe;
• Eurocentric attitudes to Africa (which was to become united with Europe into "Atlantropa" or Eurafrica), and
• Neo-colonial geopolitics, which saw the world divided into three blocs—America, Asia, and Atlantropa.

Active support was limited to architects and planners from Germany and a number of other primarily northern European countries. Critics derided it for various faults, ranging from lack of any cooperation of Mediterranean countries in the planning to the impacts it would have had on the historic coastal communities left stranded inland when the sea receded. The project reached great popularity in the late 1920s to the early 1930s, and for a short period again, in the late 1940s to the early 1950s, but soon disappeared from general discourse again after Sörgel's death.

🔗 Food and drink 🔗 Plants

Romanesco broccoli (also known as Roman cauliflower, Broccolo Romanesco, Romanesque cauliflower, or simply Romanesco) is an edible flower bud of the species Brassica oleracea. First documented in Italy in the 16th century, it is chartreuse in color, and has a form naturally approximating a fractal. When compared to a traditional cauliflower, it has a firmer texture and delicate, nutty flavor.

The Dunning–Kruger effect is a cognitive bias in which people with low ability at a task overestimate their ability. It is related to the cognitive bias of illusory superiority and comes from people's inability to recognize their lack of ability. Without the self-awareness of metacognition, people cannot objectively evaluate their level of competence.

As described by social psychologists David Dunning and Justin Kruger, the bias results from an internal illusion in people of low ability and from an external misperception in people of high ability; that is, "the miscalibration of the incompetent stems from an error about the self, whereas the miscalibration of the highly competent stems from an error about others". Colloquially, people experiencing this bias are said to be "on Mount Stupid".

But in spite of the inherent appeal of Dunning and Kruger's claimed results, which align with many people's just world theories, their conclusions are strongly challenged when subjected to mathematical analysis and comparisons across cultures.

🔗 United States 🔗 Biography 🔗 Computing 🔗 Women scientists 🔗 Biography/science and academia 🔗 Women's History 🔗 Chicago 🔗 Catholicism 🔗 United States/Iowa

Mary Kenneth Keller, B.V.M. (December 17, 1913 – January 10, 1985) was an American Roman Catholic religious sister, educator and pioneer in computer science. She and Irving C. Tang were the first two people to earn a doctorate in computer science in the United States.

🔗 Philosophy 🔗 Philosophy/Logic

Bulverism is a term for a rhetorical fallacy that combines circular reasoning with presumption or condescenscion. The method of Bulverism is to "assume that your opponent is wrong, and explain his error." The Bulverist assumes a speaker's argument is invalid or false and then explains why the speaker came to make that mistake, even if the opponents's claim is actually right, attacking the speaker or the speaker's motive. The term Bulverism was coined by C. S. Lewis to poke fun at a very serious error in thinking that, he alleges, recurs often in a variety of religious, political, and philosophical debates.

Similar to Antony Flew's "subject/motive shift", Bulverism is a fallacy of irrelevance. One accuses an argument of being wrong on the basis of the arguer's identity or motive, but these are strictly speaking irrelevant to the argument's validity or truth.

🔗 Board and table games

18XX is the generic term for a series of board games that, with a few exceptions, recreate the building of railroad corporations during the 19th century; individual games within the series use particular years in the 19th century as their title (usually the date of the start of railway development in the area of the world they cover), or "18" plus a two or more letter geographical designator (such as 18EU for a game set in the European Union). The games 2038, set in the future, and Poseidon and Ur, 1830 BC, both set in ancient history, are also regarded as 18XX titles as their game mechanics and titling nomenclature are similar despite variance from the common railroad/stock-market theme.

The 18XX series has its origins in the game 1829, first produced by Francis Tresham in the mid-1970s. 1829 was chosen as it was the year of the Rainhill Trials. 1830 was produced by Avalon Hill in 1986, and was the first game of the series widely available in the United States; it is seen as the basic 18XX game by the U.S. audience.

In addition to traditionally published games, the 18XX series has spawned self-published variants and games published by low-volume game companies.

With few exceptions (such as 2038), 18XX titles are multiplayer board games without random variables in their game mechanics.