Misplaced Pages

#541458

77-417: In the context of signal processing , an image is a distributed amplitude of color(s). In optics , the term "image" (or "optical image") refers specifically to the reproduction of an object formed by light waves coming from the object. A volatile image exists or is perceived only for a short period. This may be a reflection of an object by a mirror, a projection of a camera obscura , or a scene displayed on

154-465: A cathode-ray tube . A fixed image , also called a hard copy , is one that has been recorded on a material object, such as paper or textile . A mental image exists in an individual's mind as something one remembers or imagines. The subject of an image does not need to be real; it may be an abstract concept such as a graph or function or an imaginary entity. For a mental image to be understood outside of an individual's mind, however, there must be

231-476: A "cult" value as an example of artistic beauty. Following years of various reproductions of the painting, the portrait's "cult" status has little to do with its original subject or the artistry. It has become famous for being famous, while at the same time, its recognizability has made it a subject to be copied, manipulated, satirized, or otherwise altered in forms ranging from Marcel Duchamp's L.H.O.O.Q . to Andy Warhol 's multiple silk-screened reproductions of

308-435: A (usually) male viewer. The documentary film scholar Bill Nichols has also studied how apparently "objective" photographs and films still encode assumptions about their subjects. Images perpetuated in public education, media, and popular culture have a profound impact on the formation of such mental images: What makes them so powerful is that they circumvent the faculties of the conscious mind but, instead, directly target

385-466: A Peculiar Class of Optical Deceptions . Two instances of rotating wheels that appeared to stand still had been pointed out to him and he had read about the somewhat similar palisade illusion in Roget's article. Faraday started experimenting with rotations of toothed cardboard wheels. Several effects had already been described by Plateau, but Faraday also simplified the experiment by looking at a mirror through

462-417: A black one with cut-out patterns. When the discs spin and the top disc is retarded into regular jerky motions the toy exhibits "beautiful forms which are similar to those of the kaleidoscope " with multiplied colours. Gorham described how the colours appear mixed on the spinning top "from the duration of successive impressions on the retina". Gorham founded the principle on "the well-known experiment of whirling

539-565: A cause. Impressions of several natural phenomena and the principles of some optical toys have been attributed to persistence of vision. In 1768, Patrick D'Arcy recognised the effect in "the luminous ring that we see by turning a torch quickly, the fire wheels in the fireworks, the flattened spindle shape we see in a vibrating cord, the continuous circle we see in a cogwheel that turns with speed". Basically everything that resembles motion blur seen in fast moving objects could be regarded as "persistence of vision". The apparent line of light behind

616-428: A combination of both methods. A two-dimensional image does not need to use the entire visual system to be a visual representation. An example of this is a grayscale ("black and white") image, which uses the visual system's sensitivity to brightness across all wavelengths without taking into account different colors. A black-and-white visual representation of something is still an image, even though it does not fully use

693-498: A continuous impression of the scene with intermediate brightness (as defined by the Talbot-Plateau law ). Since its introduction, the term "persistence of vision" has often been mistaken to be the explanation for motion perception in optical toys like the phenakistiscope and the zoetrope , and later in cinema. This theory has been disputed since long before cinematography's breakthrough in 1895. The illusion of motion as

770-420: A cylinder (similar to the later zoetrope ) as well as a long, looped strip of paper or canvas stretched around two parallel rollers (somewhat similar to film) and a theater-like frame (much like the later praxinoscope ). In January 1834, William George Horner also suggested a cylindrical variation of Plateau's phénakisticope, but he did not manage to publish a working version. William Ensign Lincoln invented

847-495: A fast moving luminous object is known as the "sparkler's trail effect", since it is commonly known from the use of sparklers . The effect has occasionally been applied in the arts by writing or drawing with a light source recorded by a camera with a long exposure time. This concept has been further developed into media with computer-controlled moving light sources (nowadays mostly LED light ), known as S.W.I.M. (Sequential Wave Imprinting Machine). However, like video and television,

SECTION 10

#1732773265542

924-455: A form of record-keeping; as an element of spiritual, religious, or magical practice; or even as a form of communication. Early writing systems , including hieroglyphics , ideographic writing, and even the Roman alphabet , owe their origins in some respects to pictorial representations. Images of any type may convey different meanings and sensations for individual viewers, regardless of whether

1001-400: A fraction of a second. The traditional standard for the display of individual frames by a motion picture projector has been 24 frames per second (FPS) since at least the commercial introduction of "talking pictures" in the late 1920s, which necessitated a standard for synchronizing images and sounds. Even in electronic formats such as television and digital image displays, the apparent "motion"

1078-431: A lens and a large moving comb with teeth causing alternating colors to be projected successively. If this was done quickly enough, the alternating colours could no longer be perceived separately but were seen as white. Newton compared its principle to the sparkler's trail effect: a gyrating burning coal could appear as a circle of fire because "the sensation of the coal in the several places of that circle remains impress'd on

1155-442: A measured signal. According to Alan V. Oppenheim and Ronald W. Schafer , the principles of signal processing can be found in the classical numerical analysis techniques of the 17th century. They further state that the digital refinement of these techniques can be found in the digital control systems of the 1940s and 1950s. In 1948, Claude Shannon wrote the influential paper " A Mathematical Theory of Communication " which

1232-822: A mirror. After several attempts and many difficulties Plateau managed to animate the figures between the slits in a disc when he constructed the first effective model of the phénakisticope in November or December 1832 . Plateau published his then unnamed invention in a January 20, 1833 letter to Correspondance Mathématique et Physique . Simon Stampfer claimed to have independently and almost simultaneously invented his very similar Stroboscopischen Scheiben oder optischen Zauberscheiben (stroboscopic discs or optical magic discs) soon after he read about Faraday's findings in December 1832. Stampfer also mentioned several possible variations of his stroboscopic invention, including

1309-439: A myth. When contrasting the theory of persistence of vision with that of phi phenomena, an understanding emerges that the eye is not a camera and does not see in frames per second. In other words, vision is not as simple as light registering on a medium since the brain has to make sense of the visual data the eye provides and construct a coherent picture of reality. Although psychologists and physiologists have rejected

1386-452: A result of fast intermittent presentations of sequential images is a stroboscopic effect , as explained in 1833 by Simon Stampfer (one of the inventors of the stroboscopic disc, a.k.a. phenakistiscope). Early descriptions of the illusion often attributed the effect purely to the physiology of the eye, particularly of the retina . Nerves and parts of the brain later became accepted as important factors. Sensory memory has been cited as

1463-474: A spinning cone (or top) appears as a circle of that color and a line on the top makes the whole surface appear in that color. "Because of the swiftness of the movement we receive the impression of the line on every part of the cone as the line moves." In the 11th century Ibn al-Haytham , who was familiar with Ptolemy's writings, described how colored lines on a spinning top could not be discerned as different colors but appeared as one new color composed of all of

1540-406: A stick, ignited at one end" (a.k.a. the sparkler's trail effect). A pencil or another rigid straight line can appear as bending like flexible rubber when it is wiggled fast enough between fingers, or otherwise undergoing rigid motion. Persistence of vision has been discarded as sole cause of the illusion. It is thought that the eye movements of the observer fail to track the motions of features of

1617-509: A way of conveying that mental image through the words or visual productions of the subject. The broader sense of the word 'image' also encompasses any two-dimensional figure, such as a map , graph , pie chart , painting , or banner . In this wider sense, images can also be rendered manually, such as by drawing , the art of painting, or the graphic arts (such as lithography or etching ). Additionally, images can be rendered automatically through printing , computer graphics technology, or

SECTION 20

#1732773265542

1694-401: Is a single static image. This phrase is used in photography, visual media , and the computer industry to emphasize that one is not talking about movies, or in very precise or pedantic technical writing such as a standard . A moving image is typically a movie ( film ) or video , including digital video . It could also be an animated display , such as a zoetrope . A still frame

1771-403: Is a still image derived from one frame of a moving one. In contrast, a film still is a photograph taken on the set of a movie or television program during production, used for promotional purposes. In image processing , a picture function is a mathematical representation of a two-dimensional image as a function of two spatial variables . The function f(x,y) describes the intensity of

1848-450: Is a type of non-linear signal processing, where polynomial systems may be interpreted as conceptually straightforward extensions of linear systems to the non-linear case. Statistical signal processing is an approach which treats signals as stochastic processes , utilizing their statistical properties to perform signal processing tasks. Statistical techniques are widely used in signal processing applications. For example, one can model

1925-416: Is actually the result of many individual lines giving the impression of continuous movement. This phenomenon has often been described as " persistence of vision ": a physiological effect of light impressions remaining on the retina of the eye for very brief periods. Even though the term is still sometimes used in popular discussions of movies, it is not a scientifically valid explanation. Other terms emphasize

2002-574: Is either Analog signal processing is for signals that have not been digitized, as in most 20th-century radio , telephone, and television systems. This involves linear electronic circuits as well as nonlinear ones. The former are, for instance, passive filters , active filters , additive mixers , integrators , and delay lines . Nonlinear circuits include compandors , multipliers ( frequency mixers , voltage-controlled amplifiers ), voltage-controlled filters , voltage-controlled oscillators , and phase-locked loops . Continuous-time signal processing

2079-421: Is for sampled signals, defined only at discrete points in time, and as such are quantized in time, but not in magnitude. Analog discrete-time signal processing is a technology based on electronic devices such as sample and hold circuits, analog time-division multiplexers , analog delay lines and analog feedback shift registers . This technology was a predecessor of digital signal processing (see below), and

2156-489: Is for signals that vary with the change of continuous domain (without considering some individual interrupted points). The methods of signal processing include time domain , frequency domain , and complex frequency domain . This technology mainly discusses the modeling of a linear time-invariant continuous system, integral of the system's zero-state response, setting up system function and the continuous time filtering of deterministic signals Discrete-time signal processing

2233-419: Is seen from experience; thus when the lightning moves among dark clouds the speed of its sinuous flight makes its whole course resemble a luminous snake. So in like manner if you wave a lighted brand its whole course will seem a ring of flame. This is because the organ of perception acts more rapidly than the judgment." In his 1704 book Opticks , Isaac Newton (1642–1726/27) described a machine with prisms,

2310-705: Is still used in advanced processing of gigahertz signals. The concept of discrete-time signal processing also refers to a theoretical discipline that establishes a mathematical basis for digital signal processing, without taking quantization error into consideration. Digital signal processing is the processing of digitized discrete-time sampled signals. Processing is done by general-purpose computers or by digital circuits such as ASICs , field-programmable gate arrays or specialized digital signal processors . Typical arithmetical operations include fixed-point and floating-point , real-valued and complex-valued, multiplication and addition. Other typical operations supported by

2387-497: The Royal Society on December 9, 1824. He added: "It is also to be noticed that, however rapidly the wheel revolves, each individual spoke, during the moment it is viewed, appears to be at rest." Roget claimed that the illusion is due to the fact "that an impression made by a pencil of rays on the retina, if sufficiently vivid, will remain for a certain time after the cause has ceased." He also provided mathematical details about

Image - Misplaced Pages Continue

2464-580: The light spectrum visible to the human eye and converting such signals into recognizable images. Aside from sculpture and other physical activities that can create three-dimensional images from solid material, some modern techniques, such as holography , can create three-dimensional images that are reproducible but intangible to human touch. Some photographic processes can now render the illusion of depth in an otherwise "flat" image, but "3-D photography" ( stereoscopy ) or " 3-D film " are optical illusions that require special devices such as eyeglasses to create

2541-400: The probability distribution of noise incurred when photographing an image, and construct techniques based on this model to reduce the noise in the resulting image. In communication systems, signal processing may occur at: Persistence of vision Persistence of vision is the optical illusion that occurs when the visual perception of an object does not cease for some time after

2618-453: The rays of light proceeding from it have ceased to enter the eye . The illusion has also been described as "retinal persistence", "persistence of impressions", simply "persistence" and other variations. A very commonly given example of the phenomenon is the apparent fiery trail of a glowing coal or burning stick while it is whirled around in the dark. Many explanations of the illusion actually seem to describe positive afterimages and

2695-480: The Age of Mechanical Reproduction." Benjamin argues that the mechanical reproduction of images, which had accelerated through photographic processes in the previous one hundred years or so, inevitably degrades the "authenticity" or quasi-religious "aura" of the original object. One example is Leonardo da Vinci 's Mona Lisa , originally painted as a portrait, but much later, with its display as an art object, it developed

2772-513: The Greek philosopher Plato described our apparent reality as a copy of a higher order of universal forms . As copies of a higher reality, the things we perceive in the world, tangible or abstract, are inevitably imperfect. Book 7 of The Republic offers Plato's " Allegory of the Cave ," where ordinary human life is compared to being a prisoner in a darkened cave who believes that shadows projected onto

2849-738: The appearing curvatures. As a university student Joseph Plateau noticed in some of his early experiments that when looking from a small distance at two concentric cogwheels which turned fast in opposite directions, it produced the optical illusion of a motionless wheel. He later read Peter Mark Roget's 1824 article and decided to investigate the phenomenon further. He published his findings in Correspondance Mathématique et Physique in 1828 and 1830. In 1829 Plateau presented his then unnamed anorthoscope in his doctoral thesis Sur quelques propriétés des impressions produites par la lumière sur l'organe de la vue . The anorthoscope

2926-458: The case of shooting stars, whose light seems distended on account of their speed of motion, all according to the amount of perceptible distance it passes along with the sensible impression that arises in the visual faculty." Porphyry (circa 243–305) in his commentary on Ptolemy's Harmonics describes how the senses are not stable but confused and inaccurate. Certain intervals between repeated impressions are not detected. A white or black spot on

3003-496: The cave's wall comprise actual reality. Since art is itself an imitation, it is a copy of that copy and all the more imperfect. Artistic images, then, not only misdirect human reason away from understanding the higher forms of true reality, but in imitating the bad behaviors of humans in depictions of the gods, they can corrupt individuals and society. Echoes of such criticism have persisted across time, accelerating as image-making technologies have developed and expanded immensely since

3080-409: The colors of the lines. He deducted that sight needs some time to discern a color. al-Haytam also noted that the top appeared motionless when spun extremely quickly "for none of its points remains fixed in the same spot for any perceptible time". Leonardo da Vinci wrote in a notebook: "Every body that moves rapidly seems to colour its path with the impression of its hue. The truth of this proposition

3157-651: The complex cognitive operations of the brain and the human visual system. " Flicker fusion ", the " phi phenomenon ", and " beta movement " are among the terms that have replaced "persistence of vision", though no one term seems adequate to describe the process. Image-making seems to have been common to virtually all human cultures since at least the Paleolithic era . Prehistoric examples of rock art —including cave paintings , petroglyphs , rock reliefs , and geoglyphs —have been found on every inhabited continent. Many of these images seem to have served various purposes: as

Image - Misplaced Pages Continue

3234-506: The definitive zoetrope with exchangeable animation strips in 1865 and had it published by Milton Bradley and Co. in December 1866. In his 1833 patent and his explanatory pamphlet for his stroboscopic discs, Simon Stampfer emphasized the importance of the interruptions of the beams of light reflected by the drawings, while a mechanism would transport the images past the eyes at an appropriate speed. The pictures had to be constructed according to certain laws of physics and mathematics, including

3311-423: The different colors of sectors mixed together into one color and how dots appeared as circles when the wheel was spinning very fast. When lines are drawn across the axis of the disc they make the whole surface appear to be of a uniform color. "The visual impression that is created in the first revolution is invariably followed by repeated instances that subsequently produce an identical impression. This also happens in

3388-583: The duration may differ between different observers, light intensities of spinning objects, colours and viewing distances. He planned further experiments to determine such possible differences, but no results seem to have been published. In 1821 the Quarterly Journal of Science, Literature, and The Arts published a "letter to the editor" with the title Account of an Optical Deception. It was dated Dec. 1, 1820 and attributed to "J.M.", possibly publisher/editor John Murray himself. The author noted that

3465-409: The first Thaumatrope was published by W. Phillips (in anonymous association with John Ayrton Paris ). The fact that the pictures on either side of the twirling disc seem to blend together into one image has often falsely been presented as an illustration of the effect of persistence of vision (the fusion instead depends on stroboscopic interruptions and the compatibility of the mental impressions of

3542-493: The form of idols . In recent years, militant extremist groups such as the Taliban and ISIS have destroyed centuries-old artifacts, especially those associated with other religions. Virtually all cultures have produced images and applied different meanings or applications to them. The loss of knowledge about the context and connection of an image to its object is likely to result in different perceptions and interpretations of

3619-712: The hardware are circular buffers and lookup tables . Examples of algorithms are the fast Fourier transform (FFT), finite impulse response (FIR) filter, Infinite impulse response (IIR) filter, and adaptive filters such as the Wiener and Kalman filters . Nonlinear signal processing involves the analysis and processing of signals produced from nonlinear systems and can be in the time, frequency , or spatiotemporal domains. Nonlinear systems can produce highly complex behaviors including bifurcations , chaos , harmonics , and subharmonics which cannot be produced or analyzed using linear methods. Polynomial signal processing

3696-570: The illusion of depth. Copies of 3-dimensional images have traditionally had to be crafted one at a time, usually by an individual or team of artisans . In the modern age, the development of plastics and other technologies made it possible to create multiple copies of a 3-dimensional object with less effort; the advent and development of " 3-D printing " has expanded that capability. "Moving" two-dimensional images are actually illusions of movement perceived when still images are displayed in sequence, each image lasting less, and sometimes much less, than

3773-475: The illusion was "rather a mental than a retinal phenomenon". Early theories of persistence of vision were centered on the retina, while later theories preferred or added ideas about cognitive (brain centered) elements of motion perception . Many psychological concepts of the basic principle of animation suggested that the blanks in between the images were filled in by the mind. Max Wertheimer proved in 1912 that test subjects did not see anything in between

3850-528: The image and even of the original object itself. Through human history, one dominant form of imagery has been in relation to religion and spirituality. Such images, whether in the form of idols that are objects of worship or that represent some other spiritual state or quality, have a different status as artifacts when copies of such images sever links to the spiritual or supernatural. The German philosopher and essayist Walter Benjamin brought particular attention to this point in his 1935 essay "The Work of Art in

3927-496: The image of the sun remained in his vision after he stopped looking at it. The discovery of persistence of vision is sometimes attributed to the Roman poet Lucretius ( c.  15 October 99 BC  – c.  55 BC ), although he only mentions something similar in connection with images seen in a dream. Around 165 AD Ptolemy described in his book Optics a rotating potter's wheel with different colors on it. He noted how

SECTION 50

#1732773265542

4004-471: The image's creator intended them. An image may be taken simply as a more or less "accurate" copy of a person, place, thing, or event. It may represent an abstract concept, such as the political power of a ruler or ruling class, a practical or moral lesson, an object for spiritual or religious veneration, or an object—human or otherwise—to be desired. It may also be regarded for its purely aesthetic qualities, rarity, or monetary value. Such reactions can depend on

4081-500: The image. In modern times, the development of " non-fungible tokens " (NFTs) has been touted as an attempt to create "authentic" or "unique" images that have a monetary value, existing only in digital format. This assumption has been widely debated. The development of synthetic acoustic technologies and the creation of sound art have led to considering the possibilities of a sound-image made up of irreducible phonic substance beyond linguistic or musicological analysis. A still image

4158-405: The invention of the daguerreotype and other photographic processes in the mid-19th century. By the late 20th century, works like John Berger's Ways of Seeing and Susan Sontag 's On Photography questioned the hidden assumptions of power, race, sex, and class encoded in even realistic images, and how those assumptions and such images may implicate the viewer in the voyeuristic position of

4235-694: The making of images, even though the extent of that proscription has varied with time, place, and sect or denomination of a given religion. In Judaism, one of the Ten Commandments given by God to Moses on Mount Sinai forbids the making of "any graven image, or any likeness [of any thing] that [is] in heaven above, or that [is] in the earth beneath, or that [is] in the water under earth." In Christian history, periods of iconoclasm (the destruction of images, especially those with religious meanings or connotations) have broken out from time to time, and some sects and denominations have rejected or severely limited

4312-496: The neurological effect can be compared to the technological effect of motion blur in photography (or in film and video ). "Persistence of vision" can also be understood to mean the same as " flicker fusion ", the effect that vision seems to persist continuously when the light that enters the eyes is interrupted with short and regular intervals. When the frequency is too high for the visual system to discern differences between moments, light and dark impressions fuse together into

4389-440: The object. This effect is widely known as an entertaining "magic" trick for children. Phenomena related to flicker fusion and motion blur have been described since antiquity. Film historians have often confused flicker fusion with afterimages that arise after staring at an object, while mostly ignoring the importance of the stroboscopic effect in their explanations of motion perception in film. Aristotle (384–322 BC) noted that

4466-523: The philosophy of art. While such studies inevitably deal with issues of meaning, another approach to signification was suggested by the American philosopher, logician, and semiotician Charles Sanders Peirce . "Images" are one type of the broad category of "signs" proposed by Peirce. Although his ideas are complex and have changed over time, the three categories of signs that he distinguished stand out: A single image may exist in all three categories at

4543-752: The point at coordinates (x,y). In literature, a " mental image " may be developed through words and phrases to which the senses respond. It involves picturing an image mentally, also called imagining, hence imagery. It can both be figurative and literal. Signal processing Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing signals , such as sound , images , potential fields , seismic signals , altimetry processing , and scientific measurements . Signal processing techniques are used to optimize transmissions, digital storage efficiency, correcting distorted signals, improve subjective video quality , and to detect or pinpoint components of interest in

4620-414: The projected figures. Wertheimer supposed this "pure phi phenomenon " was a more direct sensory experience of motion. The ideal animation illusion of motion across the interval between the figures was later called " beta movement ". A visual form of memory known as iconic memory has been described as the cause of persistence of vision. Some scientists nowadays consider the entire theory of iconic memory

4697-469: The relevance of the theory of retinal persistence film viewership, film academics and theorists generally have not, and it persists in citations in many classic and modern film-theory texts. Joseph and Barbara Anderson argue that the phi phenomena privileges a more constructionist approach to the cinema ( David Bordwell , Noël Carroll , Kirstin Thompson ) whereas the persistence of vision privileges

SECTION 60

#1732773265542

4774-444: The rotating disc, that wheel seemed to stand still while the others would appear to move with different velocities or opposite direction. Plateau was inspired by Faraday's additional experiments and continued the research. In July 1832 Plateau sent a letter to Faraday and added an experimental circle with apparently abstract figures that produced a "completely immobile image of a little, perfectly regular horse" when rotated in front of

4851-471: The same time. The Statue of Liberty provides an example. While there have been countless two-dimensional and three-dimensional "reproductions" of the statue (i.e., "icons" themselves), the statue itself exists as The nature of images, whether three-dimensional or two-dimensional, created for a specific purpose or only for aesthetic pleasure, has continued to provoke questions and even condemnation at different times and places. In his dialogue, The Republic ,

4928-466: The sensorium, until the coal return again to the same place." In 1768 Patrick d'Arcy (1725-1779) reported how he had measured a duration of 0.13 seconds for one full rotation of a burning coal while it was seen as a full circle of light. He registered multiple rotations with a purpose-built machine in his garden and with the collaboration of an observer who had superior eyesight (D'Arcy's own eyesight had been damaged in an accident). D'Arcy suspected that

5005-477: The spaces between the teeth in the circumference of the cardboard disc. On 21 January 1831, Faraday presented the paper at the Royal Institution, with some new experiments. He had cut concentric series of apertures nearer to the center of a disc (representing smaller cogwheels) with small differences in the amount of "cogs" per "wheel". When looking at the mirror through the holes of one of the wheels in

5082-403: The spokes of a rotating wheel seen through fence slats appeared with peculiar curvatures (see picture). The letter concluded: "The general principles on which this deception is based will immediately occur to your mathematical readers, but a perfect demonstration will probably prove less easy than it appears on first sight". Four years later Peter Mark Roget offered an explanation when reading at

5159-447: The subconscious and affective, thus evading direct inquiry through contemplative reasoning. By doing so such axiomatic images let us know what we shall desire (liberalism, in a snapshot: the crunchy honey-flavored cereals and the freshly-pressed orange juice in the back of a suburban one-family home) and from what we shall obstain (communism, in a snapshot: lifeless crowds of men and machinery marching towards certain perdition accompanied by

5236-465: The systematic division of a movement into separate moments. He described the idea of persistence of vision only as the effect that made the interruptions go unnoticed. The idea that the motion effects in so-called "optical toys", like the phénakisticope and the zoetrope, may be caused by images lingering on the retina was questioned in an 1868 article by William Benjamin Carpenter . He suggested that

5313-543: The technology actually gets rid of the visual trail of fast-moving lights by presenting a stroboscopic sequence of very short visual cues (resulting in a sharp image, still or animated). Colors on spinning tops or rotating wheels mix together if the motion is too fast to register the details. A colored dot then appears as a circle and one line can make the whole surface appear in one uniform hue. The Newton disc optically mixes wedges of Isaac Newton 's primary colors into one (off-)white surface when it spins fast. In April 1825

5390-579: The tunes of Soviet Russian songs). What makes those images so powerful is that it is only of relative minor relevance for the stabilization of such images whether they actually capture and correspond with the multiple layers of reality, or not. Despite, or perhaps because of, the widespread use of religious and spiritual imagery worldwide, the making of images and the depiction of gods or religious subjects has been subject to criticism, censorship, and criminal penalties. The Abrahamic religions ( Judaism , Christianity , and Islam ) all have had admonitions against

5467-463: The two alternating pictures). The differences between impressions of quick alternations of two figures –depending on tachistoscope frequencies, distance between the figures, and/or variance in shapes– was studied by Max Wertheimer in 1912. These experiments inspired the theories of Gestalt psychology . In April 1858 John Gorham patented his Kaleidoscopic colour-top . This is a top on which two small discs are placed, usually one with colors and

5544-402: The two different positions in which a figure was projected by a tachistocope at frequencies that were ideal for the illusion of one figure moving from one position to the next. He used the Greek letter φ (phi) to designate illusions of motion. At higher speeds, when test subjects believed to see both positions more or less simultaneously, a moving objectless phenomenon was seen between and around

5621-512: The use of religious imagery. Islam tends to discourage religious depictions, sometimes quite rigorously, and often extends that to other forms of realistic imagery, favoring calligraphy or geometric designs instead. Depending on time and place, photographs and broadcast images in Islamic societies may be less subject to outright prohibition. In any religion, restrictions on image-making are especially targeted to avoid depictions of "false gods" in

5698-407: The viewer's context. A religious image in a church may be regarded differently than the same image mounted in a museum. Some might view it simply as an object to be bought or sold. Viewers' reactions will also be guided or shaped by their education, class, race, and other contexts. The study of emotional sensations and their relationship to any given image falls into the categories of aesthetics and

5775-591: The visual system's capabilities. On the other hand, some processes can be used to create visual representations of objects that are otherwise inaccessible to the human visual system. These include microscopy for the magnification of minute objects, telescopes that can observe objects at great distances, X-rays that can visually represent the interior structures of the human body (among other objects), magnetic resonance imaging (MRI) , positron emission tomography (PET scans) , and others. Such processes often rely on detecting electromagnetic radiation that occurs beyond

5852-543: Was a disc with an anamorphic picture that could be viewed as a clear immobile image when the disc was rotated and seen through the four radial slits of a counter-rotating disc. The discs could also be translucent and lit from behind through the slits of the counter-rotating disc. On 10 December 1830, scientist Michael Faraday wrote a paper for the Journal of the Royal Institution of Great Britain , entitled On

5929-572: Was published in the Bell System Technical Journal . The paper laid the groundwork for later development of information communication systems and the processing of signals for transmission. Signal processing matured and flourished in the 1960s and 1970s, and digital signal processing became widely used with specialized digital signal processor chips in the 1980s. A signal is a function x ( t ) {\displaystyle x(t)} , where this function

#541458