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Contenuti / Contents
Finding and Keeping the Time / Trovando e Mantenendo il Tempo
Holograms o Real and Virtual Point Trajectories
Ologrammi del Reale e Traitettorie del Punto Virtuale (estratto)
Sad Young Man on a Train / Uomo Giovane e Triste su un Treno
A Study o the Persistence o Vision
Uno Studio Sulla Persistenza Della Visione (estratto)
A Photograph o Duchamp Using a Hinged Mirror
The Truth Is Out There
La Verit St La Fuori
Fotografa di Duchamp usando uno specchio movibile
Maker, Above Below and Between
A List o Blending Modes
Elenco dei metodi di usione
An Event Over the Skies o France / Un Evento sui Cieli della Francia
Credits / Crediti
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CHAPTER 2
HOLOGRAMS OF REAL AND
VIRTUAL POINT TRA JECTORIES
2.1 Introduction
In relativity, the orbit o a point event through
space-time is called its world line. The world
line itsel is timeless, because it contains time
as one o its dimensions. Over a period o years,
we have been ascinated by the prospect o
recording world lines o moving points o light
holographically. O course, these will have
their three-dimensional (3D) spatial (the 3D
trajectory) pattern and be timeless. There will
be no way to give a direction o time and all we
know is what events (3D positions) are the time
neighbors o others.
Does this multidecade eort shed light on
relativity or make it easier to understand? Prob-
ably not. Holography can help us understand
relativity, but that work is due to Abramson, not
us. Surprisingly, our eorts have caused us to
understand holography better. In this work we
discuss holographic recording o moving points
and compare the results with various aspects o
other ways o recording a line in 3D space, such
as recording an actual luminous line, sequential
recording o points, and computer generationo lines.
2.2 Early Work
Our interest began with our eorts to generate
3D holographic images o synthetic scenes.
Why not draw the scene with a moving point
source using holography with a xed reerence
beam to record the 3d object? Figure 2.1 shows
the geometry. We moved the point continu-
ously parallel to the recording plate. Our results
were wonderul, both theoretically and experi-
mentally.
Theoretically, we showed that the coherently
time averaging an Airy pattern (the ar-eld
complex wave ront o a point source) leads to a
sin x/x pattern (the ar-eld complex wave ront
that would have been produced had the whole
line been present at once). This seemed quite
proound at the time. The coherent integration
obliterated the time dimension. It may still be
proound. We know that physics based on in-
stants and innitesimal points ails prooundly
at the quantum level. It lacks the coherent
integration into the whole. Experimentally,
we ound that the image o a clean bright line
was produced. Without that success, we would
not have persisted through the dark decades
o disappointments and partial successes that
ollowed.
Physicists progress by jumping to unwarranted
generalizations and then examining the results.
This is not so much a method as a predisposi-
tion. The obvious thing to do ater the rst suc-
cess was to move to more complex space-time
patterns. We expected, naively it now appears,
no problem in recording arbitrarily complex
scenes in this way. Instead, we encountered two
major problems. One problem we understoodalmost immediately and later were able to work
around to some extent. The other problem
we did not even understand, although we im-
mediately invented a way to work around it. We
address those two problems below.
2.2.1 Brightness Problem
As we all should have known, there is a commu-
nication-theoretic limitation on the inormation
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content o the image and how much inorma-
tion we actually see depends on the encryption
method. All o the great holographers (e.g.,
Gabor, Leith, and Denisyuk) knew that.
Figure 2.1 Schematics o the optical congura-
tion. S is a point source and H is the hologram.
We did too, but it is easy to orget. The inorma-
tion storage density (that is bits per square
centimeters or thin holograms and bits per
cubic centimeters or thick holograms) is very
material dependent. Resolution and noise are
the primary determinants. I we use all o that
capacity coherently to record a single point, the
image may have tremendous signal-to-noise
ratio (SNR). On the other hand, i we record
and reconstruct N distinct, equally bright
points, then each can have at most 1/N o the
available light and 1/N o the single-point SNR.
We emphasized the words at most. Only i
each point comes rom a hologram with unit
contrast can we achieve the 1/N brightness
condition. This would be the case i we recordedthe hologram o N coherent points simultane-
ously. However, in the case as was done in our
rst holograms, we are talking about recording
the N points sequentially. Thus we have holo-
grams rom N essentially independent points
ull overlapping and then each will use only
1/N o the shared dynamic range. The bright-
ness and SNR o each point can be at most
1/N o the values achievable or a single point.
So, whichever way we choose to record the N
points, the brighness and SNR cannot be better
than 1/N that o a single point and, usually, it
will be much lower.
Returning to our special interest here o a
continuously moving point, one should ask
the question: How big is N? That is a question
we did not even begin to answer in the middle
period o this multidecade eort.
We now know that the above discussion is over-
simplied and that there are ways, depending
on the recording material and recording condi-
tion, to improve the situation. In act, at a quite
early stage we did conceive o and demonstrate
a way to improve the brightness and SNR. We
simply moved the points close to the record-
ing medium. Because o the limited angular
divergence o the point source, the area on the
recording medium illuminated at any instant
was small. Thus there was no need or a reer-
ence beam where there was no object beam, so
we could block that part o the reerence beam.
Using a complicated optomechanical system,
we scanned a point in 3d space near the record-
ing plate and tracked it with the corresponding
part o the reerence beam. All o the time, most
o the recording material received light only
near the image o the reerence point. The rest
o the recording medium was shielded and,
thereore, not degraded. thus no point sueredthe ull 1/N penalty, and very bright images
were obtained.
2.2.2 Longitudinal Motion Problem
Initially, we did not call the problem by this
name. All we observed was that when we moved
the point in a 3D orbit (rather than in the 2D
plane, parallel to the recording medium), we did
not get very good images. In act, the images
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were terrible. We did not know why, but we did
nd a satisactory experimental way to x the
problem. We chopped (binary time modulated)
both beams. For reasons we did not understand
at the time, this allowed us to record beautiul
3D images.
This review o the history o a small part o
holography allows us to introduce the current
state o the art. We now know what the longi-
tudinal motion problem was and why chopping
cured it. We will show below that all parts o
the Airy pattern are blurred out during any
substantial longitudinal motion. Chopping
reduced the blurring eects by recording just
a very short light segment or each chopping
cycle. A general mathematical analysis o the
phenomena involved in holographic recording
o moving sources ollows below. The general
consequences will then be represented with
some demonstrative examples o special inter-
esting cases.
CAPITOLO 2
OLOGRAMMI DEL REALE E
TRAIETTORIE DEL PUNTO VIRTUALE
2.1 Introduzione
Nella relativit, lorbita di un punto attraverso
il tempo e lo spazio chiamata linea del mondo.
La linea del mondo senza tempo perch lo
contiene come una delle sue dimensioni. Sono
anni che siamo aascinati dalla prospettiva di
registrare le linee del mondo dei punti di luce in
movimento, ologracamente. Naturalmente,
questi avranno il loro schema tri-dimensionale
(3D) spaziale (traiettoria 3D) e saranno senza
tempo. Non ci sar modo di dare una traiettoria
del tempo e tutto quello che sappiamo che gli
eventi (posizioni 3D) sono i vicini del tempo
di altri.
Questo sorzo illumina sulla relativit o la
rende pi semplice da capire ? Probabilmente
no. Lolograa ci pu aiutare a capire la relativ-
it ma questo lavoro appartiene a Abramson,
non a noi. Sorprendentemente, i nostri sorzi ci
hanno portato a meglio capire la relativit. In
questo lavoro abbiamo discusso registrazioni
olograche di punti in movimento e comparato
i risultati con vari aspetti di altri modi di regis-
trare una linea nello spazio 3D, come registrareuna linea di luce, registrare sequenze di punti e
linee generate dal computer.
2.2 Lavori Precedenti
Il nostro interesse nasce con gli sorzi di gener-
are immagini olograche di scene sintetiche in
3D. Perch non disegnare la scena con un punto
di luce usando lolograa con un raggio di re-
erenza ssato per registrare un oggetto in 3D ?
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Teoricamente, abbiamo mostrato che medi-
ando coerentemente il tempo, uno schema
Airy (il campo lontano complesso dell onda
rontale di un punto onte) porta a una sin
x\x (il campo lontano complesso dell onda
rontale di un punto onte che sarebbe stato
prodotto aveva lintera linea ormanta in una
volta). Questo sembrava ben proondo a quel
tempo. Lintegrazione coerente obliterava la
dimensione del tempo. Potrebbe essere ancora
proondo. Sappiamo che sica basata su istanti
e punti innitesimali allisce proondamente ai
livelli dei quanti. Manca lintegrazione coerente
nellintero. Sperimentalmente, abbiamo trovato
che limmagine di una linea pulita e luminosa
stata prodotta. Senza quel successo non
avremmo persitito attraverso i decenni bui della
delusione e il successo parziale che ha seguito.
Il progresso dei sici salta su una non giusti-
cata generalizzazione e esaminando i risultati
in seguito. Questo non tanto un metodo
quando una predisposizione. La cosa ovvia
da are dopo un primo successo era muovere
schemi spazio temporali pi complessi. Ci
aspettavamo, adesso sembra incoscentemente,
nessun problema nel registrare arbitrariamente
scene complesse in questa maniera. Invece
incontrammo due grandi problemi. Il primo lo
capimmo quasi immediatamente e in seguito
eravamo in grado di lavorare su alcune esten-sioni. Laltro problema non lo avevamo capito
anche se avevamo immediatamente inventato
una maniera per lavorarci intorno. Trattiamo
questi due problemi di seguito.
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SAD YOUNG MAN ON A TRAIN
UOMO GIOVANE E TRISTE SU UN TRENO
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it should be noted that in this material there is no urther ormation o rods. The coarse-
ly granular precipitate is well marked in the second and third divisions, but no rods are
ormed.
It is evident that my conclusion rom a study o the material described is that
the basophilic bodies ound are not in the nature o chromidia, but are the result o indi-rect nuclear activity. As to the applicability o these results to cases in which basophilic
inclusions occur normally, it is impossible to say more than that such cases should be con-
sidered in the light o the evidence here given. The explanation oered or the ormation
o the basophilic extra nuclear bodies described is intended to be suggestive rather than
conclusive. It brings together acts which have not hitherto been associated.
A more detailed paper with illustrations is orthcoming.
Beckwith, Cora J., The Genesis o the plasma-structure in the egg o Hydractinia echinata. J. Morph., 25,
1914.
Chambers, Robert. Microdissection Studies I. A mer. J. Physiol., 43, 1917; and Microdissection Studies II,
Exper. Zool., 23, 1917.
Dantchako, Vera. Studies in cell division and cell di erentiation I, J. Morph., 27, 1916.
Gatenby. J. Brout. The Cytoplasmic Inclusions o the Germ Cells. Part V, Quar. Jour. Mic. Sci., 63, 1919.
Schaxel, Julius, Das Zusammenwirken der ZelIbestandteile bei Eireiung. Furchung, und ersten Organ-
bilung der Echinodermen. Arch. Micr. Anat. 76, 1911; Plasmastructuren, Chondriosomen und Chromidien. Anat.
Anz., 39, 1911.
Wilson. E B., Archoplasm, Centrosome, and Chromatin in the Sea-Urchin Egg, J. Morph., II, 1895.
A S T U D Y O F T H E P E R S I S T E N C E O F V I S I O N
By Arthur C. Hardy
Department o Physics, Massachusetts Institute o Technology. Communicated by Edwin II, Wilson,
February 20. 1920
Introduction.It was observed by Allen,1 while investigating the eect o the
color o the light on the persistence o vision, that there seemed to be portions o the retina
where the persistence o the retinal impression was less than on the ovea. That is, whenno fickering o the color under observation was perceptible in the center o the retina, a
slight movement o the eye in any direction which allowed the light to all upon the periph-
eral portions o the retina was sucient to destroy the apparent continuity o the light.
Allen attempted to measure the persistence or regions on the temperal side o the retina
at 10 and 20 degrees rom the axis o the eye but ound that the results were too uncer-
tain to be o any use. The writer has measured the persistence o vision or several colors
within the cone whose semi-vertical angle is nearly 40 degrees. More than one hundred
points on the retina within this area were observed or each color used. From these data,
it is possible to construct a map o the retina showing the persistence o vision or eachportion.
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Results o this sort should be o interest, not only to the illumination engineer,
but to the physiologist and the psychologist as well. I the number o observers were large
to insure that the results represent the average eye, it would be possible to construct a map
o the retina with contour lines to show equal values o the persistence o vision. This
was done by the author using the values obtained or his own eyes. The general shape othe lines was ound to coincide more or less with the shape o the color elds given by Ab-
ney.2 The extent o the color elds is, o course, dependent upon the intensity o the light.
It was not possible to show that the area o the retina covered in this investigation was
greater than the color eld or the blue or the intensity used. As the color eld or the blue
is larger in area than or any other color, it seems natural to suppose that the persistence o
vision should depend only upon the intensity o the light on portions o the retina outside
this area and should be independent o the wave-length.
Description o apparatus.The persistence o vision was measured by observ-
ing the minimum speed at which a sectored disk could be driven without destroying the
apparent continuity o the light. The source o light was a concentrated lament incandes-
cent lamp operated at constant voltage. A lens system was used to bring the rays to ocus
on the sectored disk. When the position o the disk is such that the rays do not strike it,
they diverge until they strike a ground-glass screen about 6 centimeters square. An iris
diaphragm placed just in ront o it makes the size o the illuminated area on the ground-
glass adjustable without altering the brightness. The sectored disk, the necessary electric
motor to drive it, the incandescent lamp and the lens system are all placed in a light tight
box. The eye was then placed 1 meter in ront o the ground-glass and a chin rest was pro-
vided to insure steady conditions o the retina while making the observations. Needless to
say, the investigation was carried on in total darkness. A small electric lamp operated on
the storage battery current and careully shielded was used to read the instruments when
necessary. The time or the recovery o the retina ater this stimulus was less than the time
required to place the apparatus in adjustment or the next reading.
The speed o the disk was measured by means o a small magneto and a volt-
meter calibrated to read the speed directly in revolutions per minute. The persistence o
vision was rst determined or the ovea by causing the disk to rotate at sucient speed
so that no ficker was apparent and then slowly to lose velocity until the rst ficker wasobserved. On the average, it was ound possible to determine the critical speed so that
subsequent readings would not dier by more than 2 percent. Observations were also
made with the speed o the disk increasing and the average was taken as the persistence
measure. A set o lters made by the Wratten and Wainwright Company was used one at
a time when it was desired to use light o a particular color. These lters were ound to be
very nearly monochromatic. The use o spectrum colors would be more accurate but the
intensity o the light cannot be adjusted within as wide limits.
To determine the persistence o vision or o center portions o the retina, a
small radiolight sight was used. This was mounted on a slider attached to a long rod and soconstructed as to revolve about the center o the diaphragm. In this way it was possible to
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place the sight in any desired position with respect to the center o the diaphragm. Shallow
grooves were placed at intervals along the rod so that it was possible to read the position o
the slider in the dark. In the experimental work, readings were taken about every 3 degrees
rom the center and along directions which made angles with the horizontal o 45, 90, 135,
ISO, 225, 270 and 315 degrees. The manipulation was the same as beore except that theattention was directed toward the radiolight sight and the persistence o vision measured
with the light rom the ground-glass screen alling on some other portion o the retina. It
was, o course, necessary to cover one eye during all o the experimental work.
Experimental results.Beore results could be obtained which were consistent
with themselves, it was ound necessary to take several precautions. For example, time
was given or the eye to become accustomed to the darkness. Results were obtained which
showed that 5 minutes in total darkness was sucient. It was also ound that any motion
o the body, however slight, would cause the interest to fag. For this reason, the motor
controls had to be adjusted so that the motor would change its speed slowly as it was im-
possible to operate a rheostat by hand. One hand was held on a key which was pressed at
the instant that the ficker was seen to appear or disappear and the critical speed noted.
The size o the diaphragm which seemed to give the best results was a circle o
diameter 5.84 mm. The persistence o vision is dependent upon the size o the retinal area
stimulated and also the scintillation o the light rom a small aperture caused more or less
uncertainty.3 The above aperture was chosen as being the smallest that it was practicable
to use. With the diaphragm placed at a distance o 1 meter rom the eye, the angle sub-
tended by the diaphragm at the eye is 3-30.
As has already been said, the persistence o vision was determined or several
colors and in each case the persistence was measured or about one hundred points on the
retina lying inside a circle which is the base o a cone whose semivertical angle is 38.7.
No attempt will be made to give the results in ull. They represent the persistence o an
impression on the retina o the eye o the author. The eye is known to be normal or color
perception but has a moderate amount o astigmatism which should not aect the persis-
tence o vision. A ew results will be given to show the nature o the inerences which have
be drawn rom the investigation.
For red light (6776 A) the persistence o vision in the ovea was 0.0209 second.The persistence or points lying at equal distances rom the ovea was ound to be very
nearly the same. That is, i lines are drawn showing equal values o the persistence o vi-
sion, they appear to approximate circles with the ovea at the center. The deviation rom
the circle is enough to make them resemble the limits o the color elds or the retina. The
circles are in every case fattened so that the major axis o the resulting ellipse is horizon-
tal. The persistence is less or the ovea than or any other part o the retina, and there is
a steady increase in the persistence nearly proportional to the distance rom the ovea.
The maximum value observed occurs on the nasal side o the retina at about 88 rom
the ovea. The persistence is slightly greater on the nasal side than on the temporal. Themaximum value is 0.109 second.
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For the yellow-green (3310 A) very similar results were obtained. The persis-
tence o vision or the ovea is 0.0179 second and is less than any other portion o the reti-
na. The lines o equal values o the persistence are ellipses with the major axes horizontal.
The persistence is still slightly greater on the nasal side. The maximum value is observed
to occur or the same region as or the red light but the maximum in this case is 0.0339second showing that the persistence is more nearly constant over the whole retina.
For the blue-violet (4631 A) the persistence o the ovea is 0.0346 second. There
is little change in the persistence or dierent portions o the retina. The region which
gave a maximum value or the red and the yellow-green, now gives a value o 0.0339 sec-
ond or slightly less than the ovea. The maximum occurs about 7 rom the ovea on the
nasal side and is 0.0401 second. The minimum o 0.0305 second occurs on the temporal
side at an angle o 35 rom the ovea. The change between the maximum and minimum
amounts only to the dierence between 1/25 second and 1/35 second. For the blue-violet
light used, the persistence is very nearly constant over the whole retina.
It will be noticed that these values or the persistence are smaller than those
which are sometimes quoted. The values given here represent the time required or the im-
pression on the retina to ade suciently to be noticed when compared to a resh stimulus.
They do not represent the time or the total extinction o the retinal image.
The above results were obtained at the laboratories o the Department o Phys-
ics at the University o Caliornia.
1Physic. Rev., 28, 1909 (48).2 Sir William Abncy,Researches in Color Vision, p. 190, et. seq.3 See Almey, loc. cit., p. 181.
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U N O S T U D I O S U L L A P E R S I S T E N Z A D E L L A V I S I O N E
Di Arthur C. Hardy
Dipartimento di Fisica, Massachusetts Institute o Technology. Comunicato by Edwin II, Wilson, 20 Feb-
braio 1920; (estratto)
Per la luce rossa (6776 A) la persistenza della visione nella ovea era 0,0209sec. Fu scoperto che la persistenza per i punti disposti a distanze uguali dalla ovea era
quasi la stessa. Se linee sono tracciate mostrando valori uguali della persistenza della vi-
sione, sembrano approssimare cerchi con la ovea al centro. La deviazione dal cerchio
suciente per arli assomigliare ai limiti del colore dei campi per la retina. I cerchi sono
schiacciati in tutti i casi cos che lasse maggiore della risultante ellisse orizzontale. La
persistenza minore sulla ovea che in ogni altra parte della retina e si nota un costante
aumento quasi proporzionale alla distanza dalla stessa. Il valore massimo osservato vi-
cino al lato nasale della retina a circa 88 dalla ovea. La persistenza e leggermente mag-
giore sul lato nasale che su quello della temperal. Il valore massio 0.109 secondi.
Per la luce giallo-verde (3310 A) sono stati ottenuti risultati molti simili. La
persistenza della luce nella ovea 0,0179 secondi ed ineriore che in ogni altra porzione
della retina. Le linee di valori uguali della persistenza sono ellissi con lasse maggiore oriz-
zontale. La persistenza ancora leggermente pi alta sul lato nasale. Il valore massimo
accade per la stessa regione della luce rossa ma in questo caso il massimo 0,0339 secondi
mostrando che la persistenza pi costante su tutta la retina.
Per il blu-viola (4631 A) la persistenza nella ovea (0,0346 secondi) C un pic-
colo cambio nella persistenza per porzioni dierenti della retina. La regione che ha dato
un valore massimo per il rosso e giallo-verde adesso d un valore di 0,0339 secondi o poco
meno della ovea. Il massimo si registra circa a 7 dalla ovea sul lato nasale ed 0,0401
secondi. Il minimo 0,0305 secondi, si mostra sul lato temporale ad un angolo di 35 dalla
ovea. Il cambio tr il massimo e il minimo ammonta solo alla dierenza tr 1\25 secondi e
1\35 secondi. Per la luce blu-viola usata la persistenza molto vicina alla costanza su tutta
la retina.
Sar noticato che questi valori per la persistenza sono minori di quelli che a
volte sono quotati. I valori qu dati rappresentano il tempo richiesto per limpressione
sulla retina di sumare sucientemente orti per essere registrate quando comparate aduno stimolo resco.
I risultati di sopra sono stati ottenuti nei laboratori del Dipartimento di Fisica
dell Universit della Caliornia
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LA VERIT ST LA FUORI
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83. Fotografa di Duchamp usando uno specchio movibile, 1917.
Il piacere di Duchamp per le nuove maniere popolari e oggetti tecnologici si estende naturalmente
alla otograa, di cui ha esplorato le varie dimensioni durante tutta la vita. Qu, il ripetuto uomo
di ronte allo specchio sembra essere prodotto senza il otograo, una specie di autoritratto
automatico che lascia la domanda dell autoriet irrisolta. Gli amici di Duchamp, Francis Picabia
e Henri-Pierre Roch avevano scattoto otograe simili, probabilmente nella stessa occasione: 10
otobre 1917 al Broadway Photo Shop di New York.
Se richiamiamo il commento di Duchamp a Pierre Cabanne riguardo le altre unzioni che la pittura
aveva ricoperto in passato: religiosa, losoca, morale, in quale dimensione ha inteso Duchamp
il Grande Vetro per avere una visione concettuale che poteva riormare la unzione dell arte ? O,
per dirlo in altre parole, che unzione hanno nel Grande Vetro le diverse reerenze alla religione,
mitologia e letteratura ? Abbiamo visto come scienza e prospettiva come modi di descrivere il
reale avevano una ruolo nella genesi della sua immagineria. Cosa diciamo di sistemi di credenze o
miti di tipo dierente ?
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MAKER, BEWEEN ABOVE AND BELOW
wo or three points o departureWhere edge blank eddiesTe texure o receivabilityBy
Vectors may saturatePieces o layered approximations received
Te suracing o a parallel dri,generating a sense o out and in
Angular spin, the depth-maker o a suraceDistance o time, pre-holeunneling volumes o degrees, as i
broken tubesWithin but between the numbers being counted
Te setting o a broken railTe enormous movability o a sucking passage (omnidirectional)Random, partial shrinking
Appearance o some prole junctures, some linear burps, many
16. Review and Sel-Criticism.94.
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Volumes exchanged, a speed o shiing
Place or construction o a core o exibility only
Difuse receding which parallels and contourswaiting texture
Te unique range o elasticities oimpressionable stretching, not yet texture
Te regulating o reection, deection, inectionCoalescence o sound joints, guidesRealization o mounting and push o duration (instant group)
Both senders and receivers, congurational coverings onall and any scalePull o breatho keep the end in sightAs always the necessity o out o the blue, to and romA sudden drop into a scale o action
Te call o continuity
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A LIST OF BLENDING MODES
Normal
Edits or paints each pixel to make it the result
color. This is the deault mode. (Normal mode
is called Threshold when youre working with a
bitmapped or indexed-color image.)
Dissolve
Edits or paints each pixel to make it the result
color. However, the result color is a random
replacement o the pixels with the base color or
the blend color, depending on the opacity at any
pixel location.
Darken
Looks at the color inormation in each channel
and selects the base or blend colorwhichever
is darkeras the result color. Pixels lighter
than the blend color are replaced, and pixels
darker than the blend color do not change.
Multiply
Looks at the color inormation in each channel
and multiplies the base color by the blend color.
The result color is always a darker color. Mul-
tiplying any color with black produces black.
Multiplying any color with white leaves the
color unchanged. When youre painting with
a color other than black or white, successive
strokes with a painting tool produce progres-sively darker colors. The eect is similar to
drawing on the image with multiple marking
pens.
Color Burn
Looks at the color inormation in each channel
and darkens the base color to refect the blend
color by increasing the contrast. Blending with
white produces no change.
Linear Burn
Looks at the color inormation in each channel
and darkens the base color to refect the blend
color by decreasing the brightness. Blending
with white produces no change.
Lighten
Looks at the color inormation in each channel
and selects the base or blend colorwhichever
is lighteras the result color. Pixels darker
than the blend color are replaced, and pixels
lighter than the blend color do not change.
Screen
Looks at each channels color inormation
and multiplies the inverse o the blend and
base colors. The result color is always a lighter
color. Screening with black leaves the color un-
changed. Screening with white produces white.
The eect is similar to projecting multiple
photographic slides on top o each other.
Color Dodge
Looks at the color inormation in each channel
and brightens the base color to refect the blend
color by decreasing the contrast. Blending with
black produces no change.
Overlay
Multiplies or screens the colors, depending on
the base color. Patterns or colors overlay theexisting pixels while preserving the highlights
and shadows o the base color. The base color is
not replaced, but mixed with the blend color to
refect the lightness or darkness o the original
color.
Sot Light
Darkens or lightens the colors, depending on
the blend color. The eect is similar to shining
a diused spotlight on the image. I the blend
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color (light source) is lighter than 50% gray, the
image is lightened as i it were dodged. I the
blend color is darker than 50% gray, the image
is darkened as i it were burned in. Painting
with pure black or white produces a distinctly
darker or lighter area, but does not result in
pure black or white.
Linear Dodge (Add)
Looks at the color inormation in each channel
and brightens the base color to refect the blend
color by increasing the brightness. Blending
with black produces no change.
Hard Light
Multiplies or screens the colors, depending on
the blend color. The eect is similar to shining
a harsh spotlight on the image. I the blend
color (light source) is lighter than 50% gray,
the image is lightened, as i it were screened.
This is useul or adding highlights to an image.
I the blend color is darker than 50% gray, the
image is darkened, as i it were multiplied. This
is useul or adding shadows to an image. Paint-
ing with pure black or white results in pure
black or white.
Vivid Light
Burns or dodges the colors by increasing or
decreasing the contrast, depending on the
blend color. I the blend color (light source) islighter than 50% gray, the image is lightened
by decreasing the contrast. I the blend color is
darker than 50% gray, the image is darkened by
increasing the contrast.
Linear Light
Burns or dodges the colors by decreasing or
increasing the brightness, depending on the
blend color. I the blend color (light source) is
lighter than 50% gray, the image is lightened by
increasing the brightness. I the blend color is
darker than 50% gray, the image is darkened by
decreasing the brightness.
Pin Light
Replaces the colors, depending on the blend
color. I the blend color (light source) is lighter
than 50% gray, pixels darker than the blend
color are replaced, and pixels lighter than the
blend color do not change. I the blend color is
darker than 50% gray, pixels lighter than the
blend color are replaced, and pixels darker than
the blend color do not change. This is useul or
adding special eects to an image.
Hard Mix
Adds the red, green and blue channel values o
the blend color to the RGB values o the base
color. I the resulting sum or a channel is 255
or greater, it receives a value o 255; i less than
255, a value o 0. Thereore, all blended pixels
have red, green, and blue channel values o ei-
ther 0 or 255. This changes all pixels to primary
colors: red, green, blue, cyan, yellow, magenta,
white, or black.
Dierence
Looks at the color inormation in each channel
and subtracts either the blend color rom the
base color or the base color rom the blend
color, depending on which has the greaterbrightness value. Blending with white inverts
the base color values; blending with black
produces no change.
Exclusion
Creates an eect similar to but lower in con-
trast than the Dierence mode. Blending with
white inverts the base color values. Blending
with black produces no change.
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Hue
Creates a result color with the luminance and
saturation o the base color and the hue o the
blend color.
Saturation
Creates a result color with the luminance and
hue o the base color and the saturation o the
blend color. Painting with this mode in an area
with no (0) saturation (gray) causes no change.
Color
Creates a result color with the luminance o the
base color and the hue and saturation o the
blend color. This preserves the gray levels in the
image and is useul or coloring monochrome
images and or tinting color images.
Luminosity
Creates a result color with the hue and satura-
tion o the base color and the luminance o
the blend color. This mode creates the inverse
eect o Color mode.
Lighter Color
Compares the total o all channel values or the
blend and base color and displays the higher
value color. Lighter Color does not produce a
third color, which can result rom the Lighten
blend, because it chooses the highest channel
values rom both the base and blend color tocreate the result color.
Darker Color
Compares the total o all channel values or
the blend and base color and displays the lower
value color. Darker Color does not produce a
third color, which can result rom the Darken
blend, because it chooses the lowest channel
values rom both the base and the blend color to
create the result color.
ELENCO DEI METODI DI FUSIONE
Normale
Modica o colora ciascun pixel per trasor-
marlo nel colore risultante. Questo il metodo
predenito. Il metodo normale si chiama Soglia
quando si lavora con unimmagine bitmap o in
scala di colore.
Dissolvi
Modica o colora ciascun pixel per trasormar-
lo nel colore risultante. Il colore risultante, tut-
tavia, viene creato sostituendo in modo casuale
i pixel con il colore di base o quello applicato,
secondo lopacit in ogni posizione dei pixel.
Scurisci
Esamina le inormazioni cromatiche in ciascun
canale e seleziona il colore di base o il colore
applicato, il pi scuro dei due, come colore
risultante. I pixel pi chiari del colore ap-
plicato vengono sostituiti, quelli pi scuri non
cambiano.
Moltiplica
Esamina le inormazioni cromatiche in ciascun
canale e moltiplica il colore di base per quello
applicato. Il colore risultante sempre pi
scuro. La moltiplicazione di un colore con nero
produce nero; la moltiplicazione di un colore
con bianco non cambia il colore. Se state appli-cando un colore diverso dal nero o dal bianco,
i tratti sovrapposti creati con uno strumento
di pittura producono colori gradualmente pi
scuri. Leetto simile a quello ottenuto diseg-
nando sullimmagine con pi evidenziatori.
Colore brucia
Esamina le inormazioni cromatiche in ciascun
canale e scurisce il colore di base per rifettere
quello applicato aumentando il contrasto. Luso
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del colore bianco non produce alcun cambia-
mento.
Brucia lineare
Esamina le inormazioni cromatiche in ciascun
canale e scurisce il colore di base per rifettere
quello applicato diminuendo la luminosit.
Luso del colore bianco non produce alcun
cambiamento.
Schiarisci
Esamina il colore in ciascun canale e seleziona
il colore di base o il colore applicato, il pi
chiaro dei due, come colore risultante. I pixel
pi scuri del colore applicato vengono sostituiti
e quelli pi chiari non cambiano.
Scolora
Esamina le inormazioni cromatiche in ciascun
canale e moltiplica linverso del colore applicato
e del colore di base. Il colore risultante sempre
pi chiaro. Scolorando con il nero, il colore
resta invariato. Scolorando con il bianco, si
ottiene il bianco. Leetto simile a quello otte-
nuto proiettando pi diapositive luna sullaltra.
Colore scherma
Esamina le inormazioni cromatiche in ciascun
canale e schiarisce il colore di base per rifettere
il colore applicato diminuendo il contrasto. La
usione con nero non produce alcun cambia-mento.
Scherma lineare (Aggiungi)
Esamina le inormazioni cromatiche in ciascun
canale e schiarisce il colore di base per rifettere
il colore applicato aumentando la luminosit.
La usione con nero non produce alcun cam-
biamento.
Sovrapponi
Moltiplica o scolora i colori, a seconda del
colore di base. I pattern o i colori si sovrappon-
gono ai pixel esistenti mantenendo le luci e le
ombre del colore di base. Il colore di base non
viene sostituito ma viene miscelato con il colore
applicato per rifettere la luminosit o loscurit
del colore originale.
Luce sousa
Scurisce o schiarisce i colori, a seconda del
colore applicato. Leetto simile a quello ot-
tenuto illuminando limmagine con un aretto
a luce diusa. Se il colore applicato (sorgente
luminosa) pi chiaro del grigio al 50%,
limmagine viene schiarita, come se venisse
schermata; se pi scuro del grigio al 50%,
limmagine viene scurita, come se venisse bru-
ciata. Luso del nero o del bianco puro produce
unarea chiaramente pi scura o pi chiara, ma
non produce il nero o il bianco puro.
Luce intensa
Moltiplica o scolora i colori, a seconda del
colore applicato. Leetto simile a quello ot-
tenuto illuminando limmagine con un aretto
intenso. Se il colore applicato (sorgente lumi-
nosa) pi chiaro del grigio al 50%, limmagine
viene schiarita come se osse scolorata. Ci
utile per aggiungere zone di luce allimmagine.
Se il colore applicato pi scuro del grigio al50%, limmagine viene scurita come se osse
moltiplicata. Ci utile per aggiungere le
ombre allimmagine. Luso del nero o del bianco
puro produce il nero o il bianco puro.
Luce vivida
Brucia o scherma i colori aumentando o
diminuendo il contrasto, a seconda del colore
applicato. Se il colore applicato (sorgente lumi-
nosa) pi chiaro del grigio al 50%, limmagine
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viene schiarita diminuendo il contrasto; se
pi scuro del grigio al 50%, limmagine viene
scurita aumentando il contrasto.
Luce lineare
Brucia o scherma i colori diminuendo o
aumentando la luminosit, a seconda del colore
applicato. Se il colore applicato (sorgente lumi-
nosa) pi chiaro del grigio al 50%, limmagine
viene schiarita aumentando la luminosit; se
pi scuro del grigio al 50%, limmagine viene
scurita diminuendo la luminosit.
Luce puntiorme
Sostituisce i colori, a seconda del colore appli-
cato. Se il colore applicato (sorgente luminosa)
pi chiaro del grigio al 50%, i pixel pi scuri
rispetto al colore applicato vengono sostituiti
mentre quelli pi chiari restano inalterati. Se il
colore applicato pi scuro del grigio al 50%, i
pixel pi chiari rispetto al colore applicato ven-
gono sostituiti mentre quelli pi scuri restano
inalterati. Questa opzione utile per aggiun-
gere eetti speciali a unimmagine.
Miscela dura
Aggiunge i valori dei canali rosso, verde e blu
del colore di usione ai valori RGB del colore
base. Se la somma risultante per un canale
maggiore o uguale a 255, il valore ricevuto
255; se minore di 255, il valore 0. Pertantotutti i pixel usi hanno valori dei canali rosso,
verde e blu pari a 0 o 255. Tutti i pixel vengono
quindi trasormati nei rispettivi colori primari:
rosso, verde, blu, cyan, giallo, magenta, bianco
o nero.
Dierenza
Esamina le inormazioni cromatiche in ciascun
canale e sottrae il colore applicato da quello
di base oppure il colore di base da quello ap-
plicato, a seconda di quale dei due ha il valore
di luminosit maggiore. La usione con bianco
inverte i valori del colore di base; la usione con
nero non produce alcun cambiamento.
Esclusione
Crea un eetto simile al metodo Dierenza
ma con un contrasto minore. La usione con
il bianco inverte i valori del colore di base; La
usione con nero non produce alcun cambia-
mento.
Tonalit
Crea un colore risultante con la luminanza e la
saturazione del colore di base e la tonalit del
colore applicato.
Saturazione
Crea un colore risultante con la luminosit e la
tonalit del colore di base e la saturazione del
colore applicato. Applicando questo metodo
a unarea con saturazione pari a zero (grigia),
non viene prodotto alcun cambiamento.
Colore
Crea un colore risultante con la luminosit
del colore di base e la tonalit e la saturazione
del colore applicato. In questo modo vengono
mantenuti i livelli di grigio nellimmagine; ci
risulta utile per la colorazione di immagini
monocromatiche e per tingere immagini a
colori.
Luminosit
Crea un colore risultante con la tonalit e la
saturazione del colore di base e la luminosit
del colore applicato. Questo metodo crea un
eetto opposto a quello del metodo Colore.
Colore pi chiaro
Conronta il totale di tutti i valori dei canali
per il colore di usione e di base, e visualizza il
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colore con valore pi alto. Colore pi chiaro non
genera un terzo colore, che pu essere ottenuto
tramite la usione Schiarisci, ma crea il colore
risultante scegliendo i valori dei canali pi alti
dal colore base e dal colore di usione.
Colore pi scuro
Conronta il totale di tutti i valori dei canali per
il colore di usione e di base, e visualizza il col-
ore con valore pi basso. Colore pi scuro non
genera un terzo colore, che pu essere ottenuto
tramite la usione Scurisci, ma crea il colore
risultante scegliendo i valori dei canali pi bassi
dal colore base e dal colore di usione.
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Finding and Keeping the Ti me / Trovando e Mantenendo il Tempo - National Institute o Standards and Technology - 1977
Holograms o Real and Virtual Point Trajectories / Ologrammi del Reale e Traitettorie del Punto Vir tuale - Three-dimensional
Holographic Imaging - Chung J. Kuo & Meng Hua Tsai - 2002Sad Young Man on a Train / Uomo Giovane e Triste su un Treno - Marcel Duchamp - 1911-12
A Study o the Persistence o Vi sion / Uno Studio Sulla Persistenza Della V isione - Proceedi ngs o the National Academy o Sci-
ences o the United States o America - A. C. Hardy - Communicated by Edwin B. Wilson - 1920
A Photograph o Duchamp Using a Hinged Mirror / Fotografa di Duchamp Usando uno Specchio Movibile - 1917
Maker, Above Below and Between - T he Mechanism o Meaning . Arakawa & Gins - 1978
A List o Blending Modes / Elenco Dei Met Odi di F usione - Adobe Photoshop CS3 User Guide - Adobe Systems Incor porated - 2007
An Event Over the Skies o Fr ance / Un Evento sui Cieli della Francia - Rouen, France - March 1954
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Pubblicato da Project Gentili in occasione del mostra
Published by Project Gentili on the occasion o the exhibition
Presented as the Problem, Damon Zucconi, 2009
Some Rights Reserved, 2009, Project Gentili
ISSN 1973-2163
www.damonzucconi.com
Project Gentili / 13 Via Del Carmine / 59100 Prato / Italy
T: +39 0574 400445
F: +39 0574 443704
www.projectgentili.com
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