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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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Presented as the Problem


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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.

221Vol.6. 1920 PSYCHOLOGY: A. C. HARDY


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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

Proc. N. A. S.222 PSYCHOLOGY: A. C. HARDY


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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.

223Vol.6. 1920 PSYCHOLOGY: A. C. HARDY


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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.

Proc. N. A. S.224 PSYCHOLOGY: A. C. HARDY


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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

16. Review and Sel-Criticism. 95.


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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


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


and darkens the base color to refect the blend

color by increasing the contrast. Blending with

white produces no change.

Linear Burn


and darkens the base color to refect the blend

color by decreasing the brightness. Blending

with white produces no change.

Lighten


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


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)


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


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


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


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


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


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


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)


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-



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26

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-


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


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

[email protected]

Project Gentili / 13 Via Del Carmine / 59100 Prato / Italy

T: +39 0574 400445

F: +39 0574 443704

www.projectgentili.com

[email protected]


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