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Movements, leaders, victories and the continuing fight for equality.
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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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Moments that changed communities, movements, institutions and the nation.
In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
Visual artifacts (also artefacts) are anomalies apparent during visual representation as in digital graphics and other forms of imagery, especially photography and microscopy.
Many people who use their computers as a hobby experience artifacting due to a hardware or software malfunction. The cases can differ but the usual causes are:
The differing cases of visual artifacting can also differ between scheduled task(s).
These effects can occur in both analog and digital photography.
In microscopy, an artifact is an apparent structural detail that is caused by the processing of the specimen and is thus not a legitimate feature of the specimen. In light microscopy, artifacts may be produced by air bubbles trapped under the slide's cover slip.[1]
In electron microscopy, distortions may be produced in the drying out of the specimen. Staining can cause the appearance of solid chemical deposits that may be seen as structures inside the cell. Different techniques including freeze-fracturing and cell fractionation may be used to overcome the problems of artifacts.[1]
A crush artifact is an artificial elongation and distortion seen in histopathology and cytopathology studies, presumably because of iatrogenic compression of tissues. Distortion can be caused by the slightest compression of tissue and can provide difficulties in diagnosis.[2][3] It may cause chromatin to be squeezed out of nuclei.[2] Inflammatory and tumor cells are most susceptible to crush artifacts.[2]
![Tearing artifacts, such as can be caused by: - Microtomy with a nick or blemish in the knife edge.[4] - Traction of the sections. - Too much or too little alcohol dehydration.[4] - Sectioning calcified parts, which can be decalcified or removed.[4]](viewer.php?source=wikipedia&q=File%3AMicroscopy%20of%20liver%20parenchyma%20with%20tearing%20artifacts.jpg&result=0#selected-result)
![Small cell carcinoma is a cancer where the presence of smudging is a clue to the diagnosis.[5]](viewer.php?source=wikipedia&q=File%3AHistopathology%20of%20small%20cell%20carcinoma%20-%20nuclear%20smudging.png&result=0#selected-result)
In projectional radiography, visual artifacts that can constitute disease mimics include jewelry, clothes and skin folds.[6]
In Magnetic resonance imaging, artifacts can be classified as patient-related, signal processing-dependent or hardware (machine)-related.[7]
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
Visual artifacts (also artefacts) are anomalies apparent during visual representation as in digital graphics and other forms of imagery, especially photography and microscopy.
An MRI artifact is a visual artifact (an anomaly seen during visual representation) in magnetic resonance imaging (MRI). It is a feature appearing in an image that is not present in the original object. Many different artifacts can occur during MRI, some affecting the diagnostic quality, while others may be confused with pathology. Artifacts can be classified as patient-related, signal processing-dependent and hardware-related.
A lens flare is a visual artifact caused by light scattering, or flaring, in a lens system. This can happen through light scattered by the imaging mechanism itself, for example through internal reflection and forward scatter from material imperfections in the lens. Lenses with large numbers of elements such as zooms tend to have more lens flare, as they contain a relatively large number of interfaces at which internal scattering may occur. These mechanisms differ from the focused image generation mechanism, which uses rays that are from the reflection of light on the subject to be imaged and propagating along the intended paths in the lens system. There are two types of flare: visible artifacts and glare across the image. The glare makes the image look "washed out" by reducing contrast and color saturation (adding light to dark image regions, and adding white to saturated regions, reducing their saturation). Visible artifacts, usually in the shape of the aperture made by the iris diaphragm, are formed when light follows a pathway through the lens that contains one or more reflections from the lens surfaces. Flare is particularly caused by very bright light sources. Most commonly, this occurs when the lens is aimed toward the Sun (when the Sun is in frame or the lens is pointed sunward), and is reduced by use of a lens hood or other shade. For good-quality optical systems, and for most images (which do not have a bright light shining into the lens), flare is a secondary effect that is widely distributed across the image and thus not visible, although it does reduce contrast. In photography, lens flares are often undesirable, but they may be used intentionally to invoke a sense of drama or realism.
Hanover bars, in one of the PAL television video formats, are an undesirable visual artifact in the reception of a television image. The name refers to the city of Hanover, in which the PAL system developer Telefunken Fernseh und Rundfunk GmbH was located. The PAL system encodes color as YUV. The U (corresponding to B-Y) and V (corresponding to R-Y) signals carry the color information for a picture, with the phase of the V signal reversed (i.e. shifted through 180 degrees) on alternate lines (hence the name PAL, or phase alternate line). This is done to cancel minor phase errors in the reception process. However, if gross errors occur, complementary errors from the V signal carry into the U signal, and thus visible stripes occur. Later PAL systems introduced alterations to ensure that Hanover bars do not occur, introducing a swinging burst to the color synchronization. Other PAL systems may handle this problem differently.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Joe Louis.
