Integral imaging
Encyclopedia
Integral imaging is an autostereoscopic
or multiscopic
3D display
, meaning that it displays a 3D image without the use of special glasses on the part of the viewer. It achieves this by placing an array of microlens
es (similar to a lenticular lens
) in front of the image, where each lens looks different depending on viewing angle. Thus rather than displaying a 2D image that looks the same from every direction, it reproduces a 4D light field
, creating stereo images that exhibit parallax
when the viewer moves.
The concept was proposed in 1908 by Gabriel Lippmann
, and to date has found use largely in the related concept of lenticular printing
of static images.
proposed the use of an array of lenses placed at a picture surface to form true three dimensional pictures. He submitted this proposal to the French Academy of Sciences
under the title “La Photographie Integrale”.
The first in-depth study of lithographic printing of integral imagery was developed in 1936 by Carl Percy and Ernest Draper of the Perser Corporation. The first integral animation effect printing was proposed in 1958 by Juan Luis Ossoinak, of Argentina
.
A number of researchers continued to advance the process of Integral Photography over the last 40 years, including:
Creating 3-D integral imagery, by digitally interlacing a set of computer generated two-dimensional views, was first demonstrated in 1978 at the Tokyo Institute of Technology
in Japan
. They and others also developed experimental integral television methods. Digitally interlacing integral imagery for high-resolution color pictures was first proposed in 1989 by Ivars Villums. Many thousands of experimental images have been produced throughout the last century, by a wide variety of methods, exhibiting 3-D, animation and other effects. Research and commercialization of integral methods remains very active today including a wide body of work in integral television and other electronic displays. Integral imaging has not yet achieved significant commercial success, in part because diamond tooling molds for large plastic arrays is difficult, and in most cases prohibitively expensive. Inexpensive lens array sheets have been produced using extrusion embossing (in the same manner as lenticular sheets are made), using anilox patterned rolls, but the resulting lens array pattern, while adequate for moiré effects, is not suitable for integral imagery due to its lack of predictable geometry.
In 2006 an experimental prototype
demonstrated the use of a holographic lens array to enhance the viewing angle and DOF
of integral imaging systems.
When properly practiced, the result is credible three-dimensional imagery which coveys a realism similar to holograms. Indeed, it has been demonstrated that an integral image can very accurately reproduce the wavefront
that emanated from the original photographed or computer-generated subject, much like a hologram, but without the need for lasers to create the image; see Fig. 2. This allows the eyes to accommodate
(focus) on foreground and background elements, something not possible with lenticular
or barrier strip methods.
Integral imaging is based on a principle known as the lens “sampling effect”. To achieve this effect, the thickness of the lens array sheet is chosen so that parallel incoming light rays generally focus on the opposing side of the array, which is typically flat; see Fig. 3 (right). This flat side is known as the focal plane. It is at this plane that the micro-images are placed, one for every lens, side by side. Since each lenslet focuses to a point onto a micro-image below, an observer can never view two spots within a micro-image simultaneously; just one spot at a time, depending on the angle the observer looks though the lens. For example, if you have an array of small white dots, on an otherwise black background, behind each lens at the focal plane, any given lens will appear either completely black or white, depending on whether or not the lens is focused on a white dot, or the black background; see Fig. 3 (left). The state of each lens will vary depending on the point of observation. If all the dots are precisely ordered in a pre-calculated way, a completely different composite image can be directed to each eye of an observer, simultaneously, since each eye looks through the lens array at a different angle. The resolution of an integral image is therefore directly determined by the density of lenses in the array, since each lens effectively becomes a “dot”, or pixel
(picture element), in the picture, with the visual state of each dot being a function of the viewing angle.
at its focal plane, and an exposure is made of an illuminated object that is placed close to the lens side of the sheet, each individual lens (or pin-hole) will record its own unique micro-image of the object. The content of each micro-image changes slightly based on the position, or vantage point, of the lenslet on the array. In other words, the integral method produces a huge number of tiny, juxtaposed pictures behind the lens array onto the film. After development, the film is realigned with the lens sheet and a composite, spatial reconstruction of the object is re-created in front of the lens array, that can be viewed from arbitrary directions within a limited viewing angle.
, integral images can be created by digitally interlacing a set of pre-determined two-dimensional views to create three-dimensional and/or animation effects. Unlike lenticular, the imagery is viewable in all directions, within a limited viewing angle. Interlaced files can be printed using a variety of devices including ink-jet printers, film recorders, half-tone proofers, digital presses and press plates for lithographic reproduction. Unique, integral-specific, half-toning methods have been proposed by Dr. Daniel Lau and Trebor Smith; see Optics Express paper
While the mass-production of integral lens arrays remains limited, they are expected to become widely accessible in the near future as the relevant replication technologies continue to evolve. Once available, these lenses, when coupled with readily available digital interlacing and effects generation software, might enable lithographic integral imagery to develop as an significant advertising medium.
Autostereoscopy
Autostereoscopy is any method of displaying stereoscopic images without the use of special headgear or glasses on the part of the viewer. Because headgear is not required, it is also called "glasses-free 3D" or "glassesless 3D"...
or multiscopic
Multiscopy
In contrast with 3D binocular stereoscopy , 3D multiscopy displays multiple angles at once...
3D display
3D display
A 3D display is any display device capable of conveying a stereoscopic perception of 3-D depth to the viewer. The basic requirement is to present offset images that are displayed separately to the left and right eye. Both of these 2-D offset images are then combined in the brain to give the...
, meaning that it displays a 3D image without the use of special glasses on the part of the viewer. It achieves this by placing an array of microlens
Microlens
A microlens is a small lens, generally with a diameter less than a millimetre and often as small as 10 micrometres . The small sizes of the lenses means that a simple design can give good optical quality but sometimes unwanted effects arise due to optical diffraction at the small features...
es (similar to a lenticular lens
Lenticular lens
A lenticular lens is an array of magnifying lenses, designed so that when viewed from slightly different angles, different images are magnified...
) in front of the image, where each lens looks different depending on viewing angle. Thus rather than displaying a 2D image that looks the same from every direction, it reproduces a 4D light field
Light field
The light field is a function that describes the amount of light faring in every direction through every point in space. Michael Faraday was the first to propose that light should be interpreted as a field, much like the magnetic fields on which he had been working for several years...
, creating stereo images that exhibit parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...
when the viewer moves.
The concept was proposed in 1908 by Gabriel Lippmann
Gabriel Lippmann
Jonas Ferdinand Gabriel Lippmann was a Franco-Luxembourgish physicist and inventor, and Nobel laureate in physics for his method of reproducing colours photographically based on the phenomenon of interference....
, and to date has found use largely in the related concept of lenticular printing
Lenticular printing
Lenticular printing is a technology in which a lenticular lens is used to produce images with an illusion of depth, or the ability to change or move as the image is viewed from different angles...
of static images.
History
On March 3, 1908, physicist Professor Gabriel LippmannGabriel Lippmann
Jonas Ferdinand Gabriel Lippmann was a Franco-Luxembourgish physicist and inventor, and Nobel laureate in physics for his method of reproducing colours photographically based on the phenomenon of interference....
proposed the use of an array of lenses placed at a picture surface to form true three dimensional pictures. He submitted this proposal to the French Academy of Sciences
French Academy of Sciences
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...
under the title “La Photographie Integrale”.
The first in-depth study of lithographic printing of integral imagery was developed in 1936 by Carl Percy and Ernest Draper of the Perser Corporation. The first integral animation effect printing was proposed in 1958 by Juan Luis Ossoinak, of Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
.
A number of researchers continued to advance the process of Integral Photography over the last 40 years, including:
- Roger de Montebello, Lesley Dudley and Robert Collier, in the United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
; - Neil Davis and Malcolm McCormick, in the United KingdomUnited KingdomThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
; - Yu. A. Dudnikov and B. K. Rozhkov, in the former Soviet UnionSoviet UnionThe Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
.
Creating 3-D integral imagery, by digitally interlacing a set of computer generated two-dimensional views, was first demonstrated in 1978 at the Tokyo Institute of Technology
Tokyo Institute of Technology
The Tokyo Institute of Technology is a public research university located in Greater Tokyo Area, Japan. Tokyo Tech is the largest institution for higher education in Japan dedicated to science and technology. Tokyo Tech enrolled 4,850 undergaraduates and 5006 graduate students for 2009-2010...
in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. They and others also developed experimental integral television methods. Digitally interlacing integral imagery for high-resolution color pictures was first proposed in 1989 by Ivars Villums. Many thousands of experimental images have been produced throughout the last century, by a wide variety of methods, exhibiting 3-D, animation and other effects. Research and commercialization of integral methods remains very active today including a wide body of work in integral television and other electronic displays. Integral imaging has not yet achieved significant commercial success, in part because diamond tooling molds for large plastic arrays is difficult, and in most cases prohibitively expensive. Inexpensive lens array sheets have been produced using extrusion embossing (in the same manner as lenticular sheets are made), using anilox patterned rolls, but the resulting lens array pattern, while adequate for moiré effects, is not suitable for integral imagery due to its lack of predictable geometry.
In 2006 an experimental prototype
Prototype
A prototype is an early sample or model built to test a concept or process or to act as a thing to be replicated or learned from.The word prototype derives from the Greek πρωτότυπον , "primitive form", neutral of πρωτότυπος , "original, primitive", from πρῶτος , "first" and τύπος ,...
demonstrated the use of a holographic lens array to enhance the viewing angle and DOF
DOF
DOF may stand for:* Deeds of Flesh, a Death Metal band* Degrees of freedom * Department of Finance , an executive department in the Philippines...
of integral imaging systems.
Description
An integral image consists of a large number of closely packed, distinct micro-images, that are viewed by an observer through an array of spherical convex lenses, one lens for every micro-image. The term “Integral” comes from the integration of all the micro images into a complete three dimensional image through the lens array. This special type of lens array is known as a fly's-eye or integral lens array; see Fig. 1.Wavefront
In physics, a wavefront is the locus of points having the same phase. Since infrared, optical, x-ray and gamma-ray frequencies are so high, the temporal component of electromagnetic waves is usually ignored at these wavelengths, and it is only the phase of the spatial oscillation that is described...
that emanated from the original photographed or computer-generated subject, much like a hologram, but without the need for lasers to create the image; see Fig. 2. This allows the eyes to accommodate
Accommodation (eye)
Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image on an object as its distance changes....
(focus) on foreground and background elements, something not possible with lenticular
Lenticular lens
A lenticular lens is an array of magnifying lenses, designed so that when viewed from slightly different angles, different images are magnified...
or barrier strip methods.
Sampling effect
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
(picture element), in the picture, with the visual state of each dot being a function of the viewing angle.
Integral photography
The first integral imaging method was “Integral Photography”. In this method the lens array is used to both record and play back a composite three-dimensional image. When an integral lens array sheet is brought into contact with a photographic emulsionEmulsion
An emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...
at its focal plane, and an exposure is made of an illuminated object that is placed close to the lens side of the sheet, each individual lens (or pin-hole) will record its own unique micro-image of the object. The content of each micro-image changes slightly based on the position, or vantage point, of the lenslet on the array. In other words, the integral method produces a huge number of tiny, juxtaposed pictures behind the lens array onto the film. After development, the film is realigned with the lens sheet and a composite, spatial reconstruction of the object is re-created in front of the lens array, that can be viewed from arbitrary directions within a limited viewing angle.
Integral digital printing
Like lenticularLenticular lens
A lenticular lens is an array of magnifying lenses, designed so that when viewed from slightly different angles, different images are magnified...
, integral images can be created by digitally interlacing a set of pre-determined two-dimensional views to create three-dimensional and/or animation effects. Unlike lenticular, the imagery is viewable in all directions, within a limited viewing angle. Interlaced files can be printed using a variety of devices including ink-jet printers, film recorders, half-tone proofers, digital presses and press plates for lithographic reproduction. Unique, integral-specific, half-toning methods have been proposed by Dr. Daniel Lau and Trebor Smith; see Optics Express paper
While the mass-production of integral lens arrays remains limited, they are expected to become widely accessible in the near future as the relevant replication technologies continue to evolve. Once available, these lenses, when coupled with readily available digital interlacing and effects generation software, might enable lithographic integral imagery to develop as an significant advertising medium.
External links
- [ftp://ftp.umiacs.umd.edu/pub/aagrawal/HistoryOfIntegralImaging/Integral_History.pdf Integral History] — Comprehensive history of integral imaging
- Videos of integral imaging-based 3D displays by Toshiba: http://www.youtube.com/watch?v=8uUWydvF18I, http://www.youtube.com/watch?v=_qR2Ofnv3n0, http://www.youtube.com/watch?v=xzZk03O06wE